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Summary: Elevated air temperature (Tair) and vapour pressure deficit (VPDair) significantly influence plant functioning, yet their relative impacts are difficult to disentangle.We examined the effects of elevated Tair (+6°C) and VPDair (+0.7 kPa) on the growth and physiology of six tropical tree species. Saplings were grown under well‐watered conditions in climate‐controlled glasshouses for 6 months under three treatments: (1) low Tair and low VPDair, (2) high Tair and low VPDair, and (3) high Tair and high VPDair. To assess acclimation, physiological parameters were measured at a set temperature.Warm‐grown plants grown under elevated VPDair had significantly reduced stomatal conductance and increased instantaneous water use efficiency compared to plants grown under low VPDair. Photosynthetic biochemistry and thermal tolerance (Tcrit) were unaffected by VPDair, but elevated Tair caused Jmax25 to decrease and Tcrit to increase. Sapling biomass accumulation for all species responded positively to an increase in Tair, but elevated VPDair limited growth.This study shows that stomatal limitation caused by even moderate increases in VPDair can decrease productivity and growth rates in tropical species independently from Tair and has important implications for modelling the impacts of climate change on tropical forests. [ABSTRACT FROM AUTHOR]

• Selenite fertilization causes toxicity at lower doses than selenate fertilization. • Selenate fertilization favored the dry mass and Se accumulation in the radish and leaves. • Selenite fertilization with 1.8 mg Se dm−3 reduced radishes dry mass. • Se accumulation in radishes and leaves correlated positively and strongly with radishes dry mass. • Selenium fertilization caused changes in the anatomy and physiology of Raphanus sativus L. plants. Selenium (Se), in low doses, provides several beneficial effects, such as plant resistance to various abiotic stresses (e.g. drought stress and low/high temperatures). However, Se excess causes toxicity, with harmful impacts such as a decline in yield. Here, we studied the effects of fertilization with different Se sources and doses applied via soil on Se accumulation, toxicity, as well as on gas exchange, and anatomy of leaves and roots of radish plants. A randomized experimental design was adopted with three replications in a 2 × 3 + 1 factorial arrangement: two Se sources (sodium selenate – Na 2 SeO 4 and sodium selenite – Na 2 SeO 3 ·5H 2 O), three Se doses applied on soil (0.6, 1.2, and 1.8 mg dm−3), and one control treatment (without Se application). Each experimental unit consisted of one pot containing six radish plants. Selenate at 1.8 mg Se dm−3 increased the Se accumulation and radish dry matter. Selenite generally caused significant changes in the anatomical part, mainly in the conductive tissues of the leaves. In leaves with selenite fertilization, it was estimated that the maximum Se accumulation would be 5.9 µg plant−1 with a rate of 2.0 mg Se dm−3. However, it was impossible to estimate the maximum Se accumulation with selenate fertilization because as the dose increased, there were also increases in accumulation, thus presenting a linear regression. The maximum Se accumulation in radishes would be 10.7 µg Se plant −1 with 1.2 mg Se dm−3 by selenite and 45.8 µg Se plant−1 with 5.0 mg Se dm−3 by selenate. Although the highest dry mass production occurred with the 1.8 mg Se dm−3 through selenite, it is recommended to use smaller doses to provide adequate Se consumption selenate. The gas exchange and the anatomy of the plants changed due to Se fertilization through selenate and selenite. [ABSTRACT FROM AUTHOR]

Summary: Climate change is simultaneously increasing carbon dioxide concentrations ([CO2]) and temperature. These factors could interact to influence plant physiology and performance. Alternatively, increased [CO2] may offset costs associated with elevated temperatures. Furthermore, the interaction between elevated temperature and [CO2] may differentially affect populations from along an elevational gradient and disrupt local adaptation.We conducted a multifactorial growth chamber experiment to examine the interactive effects of temperature and [CO2] on fitness and ecophysiology of diverse accessions of Boechera stricta (Brassicaceae) sourced from a broad elevational gradient in Colorado. We tested whether increased [CO2] would enhance photosynthesis across accessions, and whether warmer conditions would depress the fitness of high‐elevation accessions owing to steep reductions in temperature with increasing elevation in this system. Elevational clines in [CO2] are not as evident, making it challenging to predict how locally adapted ecotypes will respond to elevated [CO2].This experiment revealed that elevated [CO2] increased photosynthesis and intrinsic water use efficiency across all accessions. However, these instantaneous responses to treatments did not translate to changes in fitness. Instead, increased temperatures reduced the probability of reproduction for all accessions. Elevated [CO2] and increased temperatures interacted to shift the adaptive landscape, favoring lower elevation accessions for the probability of survival and fecundity.Our results suggest that elevated temperatures and [CO2] associated with climate change could have severe negative consequences, especially for high‐elevation populations. [ABSTRACT FROM AUTHOR]

Drought stress adversely affects growth, development, productivity, and fiber quality of cotton (Gossypium hirsutum L). Breeding strategies to enhance drought tolerance require an improved knowledge of plant drought responses necessitating proper identification of drought-tolerant genotypes of crops, including cotton. The objective of this study was to classify the selected cotton genotypes for their drought tolerance ability based on morpho-physio-biochemical traits using Hierarchical Ward's cluster analysis. Five genotypes of cotton (Takfa 3, Takfa 6, Takfa 7, Takfa 84–4, and Takfa 86–5) were selected as plant materials, and were grown under well-watered (WW; 98 ± 2% field capacity) and water-deficit (WD; 50 ± 2% field capacity) conditions for 16 days during the flower initiation stage. Data on morpho-physio-biochemical parameters and gene expression levels for these parameters were collected, and subsequently genotypes were classified either as a drought tolerant or drought susceptible one. Upregulation of GhPRP (proline-rich protein), GhP5CS (Δ1-pyrroline-5-carboxylate synthetase), and GhP5CR (Δ1-pyrroline-5-carboxylate reductase) in relation to free proline enrichment was observed in Takfa 3 genotype under WD condition. An accumulation of free proline, total soluble sugar, and potassium in plants under WD conditions was detected, which played a key role as major osmolytes controlling cellular osmotic potential. Magnesium and calcium concentrations were also enriched in leaves under WD conditions, functioning as essential elements and regulating photosynthetic abilities. Leaf greenness, net photosynthetic rate, stomatal conductance, and transpiration rate were also declined under WD conditions, leading to growth retardation, especially aboveground traits of Takfa 6, Takfa 7, Takfa 84–4, and Takfa 86–5 genotypes. An increase in leaf temperature (1.1 − 4.0 °C) and crop water stress index (CWSI > 0.75) in relation to stomatal closure and reduced transpiration rate was recorded in cotton genotypes under WD conditions compared with WW conditions. Based on the increase of free proline, soluble sugar, leaf temperature, and CWSI, as well as the decrease of aboveground growth traits and physiological attributes, five genotypes were categorized into two cluster groups: drought tolerant (Takfa 3) and drought susceptible (Takfa 6, Takfa 7, Takfa 84–4, and Takfa 86–5). The identified drought-tolerant cotton genotype, namely, Takfa 3, may be grown in areas experiencing drought conditions. It is recommended to further validate the yield traits of Takfa 3 under rainfed field conditions in drought-prone environments. [ABSTRACT FROM AUTHOR]

• Salicylic acid (SA) has encouraging effects on the growth and development of plants. • SA stimulates signalling in plants via several stress proteins and genes. • SA positively interacts with other phytohormones. • SA enhances plant tolerance towards abiotic stress. Drastic change in global climatic conditions has significantly increased the frequency of abiotic stresses, such as different temperature regimes (high, low, or freezing stress), uneven precipitation leading to flooding or drought, soil salinization, cyclones and hurricanes which pose a major challenge to the crop productivity and food security. Therefore, it becomes imperative for the global science community to engineer stress tolerance in crop plants to ensure enough food for the globe. Plant growth regulators play an important function in stress management. One putative plant hormone that aids plants in coping with biotic and abiotic stressors is salicylic acid (SA). SA also cooperates with other phytohormones, such as gibberellins, auxins, abscisic acid, jasmonic acid, ethylene, polyamines, nitric oxide, and to counter the negative effects of environmental perturbations. Moreover, SA shields plants from oxidative stress by reducing the production of reactive oxygen species in challenging circumstances. Additionally, SA stimulates gas exchange, photosynthesis, and osmolyte synthesis in plants, which counteract the damage caused by ROS. Exogenous application of SA to agricultural crops including medicinal and aromatic plants improves their abiotic stress tolerance, either individually or in combination with other phytohormones. SA can stimulate the production of secondary metabolites by controlling the expression of stress-related genes, activating or regulating several key enzymes, and balancing the ion content. The present review summarizes the various mechanisms by which SA confers abiotic stress tolerance in plants through homeostasis, signalling, and crosstalk with other phytohormones. [ABSTRACT FROM AUTHOR]

The microvasculature facilitates gas exchange, provides nutrients to cells, and regulates blood flow in response to stimuli. Vascular abnormalities are an indicator of pathology for various conditions, such as compromised vessel integrity in small vessel disease and angiogenesis in tumors. Traditional immunohistochemistry enables the visualization of tissue cross-sections containing exogenously labeled vasculature. Although this approach can be utilized to quantify vascular changes within small fields of view, it is not a practical way to study the vasculature on the scale of whole organs. Three-dimensional (3D) imaging presents a more appropriate method to visualize the vascular architecture in tissue. Here we describe the complete protocol that we use to characterize the vasculature of different organs in mice encompassing the methods to fluorescently label vessels, optically clear tissue, collect 3D vascular images, and quantify these vascular images with a semi-automated approach. To validate the automated segmentation of vascular images, one user manually segmented one hundred random regions of interest across different vascular images. The automated segmentation results had an average sensitivity of 83±11% and an average specificity of 91±6% when compared to manual segmentation. Applying this procedure of image analysis presents a method to reliably quantify and characterize vascular networks in a timely fashion. This procedure is also applicable to other methods of tissue clearing and vascular labels that generate 3D images of microvasculature. [ABSTRACT FROM AUTHOR]

Stomata play a pivotal role in regulating gas exchange between plants and the atmosphere controlling water and carbon cycles. Accordingly, we investigated the impact of ultraviolet‐B radiation, a neglected environmental factor varying with ongoing global change, on stomatal morphology and function by a Comprehensive Meta‐Analysis. The overall UV effect at the leaf level is to decrease stomatal conductance, stomatal aperture and stomatal size, although stomatal density was increased. The significant decline in stomatal conductance is marked (6% in trees and >10% in grasses and herbs) in short‐term experiments, with more modest decreases noted in long‐term UV studies. Short‐term experiments in growth chambers are not representative of long‐term field UV effects on stomatal conductance. Important consequences of altered stomatal function are hypothesized. In the short term, UV‐mediated stomatal closure may reduce carbon uptake but also water loss through transpiration, thereby alleviating deleterious effects of drought. However, in the long term, complex changes in stomatal aperture, size, and density may reduce the carbon sequestration capacity of plants and increase vegetation and land surface temperatures, potentially exacerbating negative effects of drought and/or heatwaves. Therefore, the expected future strength of carbon sink capacity in high‐UV regions is likely overestimated. Summary statement: Ultraviolet‐B radiation reduces stomatal conductance, aperture and size while increasing density. Short‐term effects are stronger than long ones, affecting grasses more than trees. Reduced conductance may lessen drought stress, but raise leaf warming, worsening heatwave damage and reducing carbon uptake. [ABSTRACT FROM AUTHOR]

Trichomes are common in plants from dry environments, and despite their recognized role in protection and defense, little is known about their role as absorptive structures and in other aspects of leaf ecophysiology. We combine anatomical and ecophysiological data to evaluate how trichomes affect leaf gas exchange and water balance during drought. We studied two congeneric species with pubescent leaves which co‐occur in Brazilian Caatinga: Croton blanchetianus (dense trichomes) and Croton adenocalyx (sparse trichomes). We found a novel foliar water uptake (FWU) pathway in C. blanchetianus composed of stellate trichomes and underlying epidermal cells and sclereids that interconnect the trichomes from both leaf surfaces. The water absorbed by these trichomes is redistributed laterally by pectin protuberances on mesophyll cell walls. This mechanism enables C. blanchetianus leaves to absorb water more efficiently than C. adenocalyx. Consequently, the exposure of C. blanchetianus to dew during drought improved its leaf gas exchange and water status more than C. adenocalyx. C. blanchetianus trichomes also increase their leaf capacity to reflect light and maintain lower temperatures during drought. Our results emphasize the multiple roles that trichomes might have on plant functioning and the importance of FWU for the ecophysiology of Caatinga plants during drought. Summary statement: We describe a novel pathway of foliar water absorption that involves stellate trichomes, sclereids and pectin protuberances that redistribute water inside the leaf. The absorption of dew water through this pathway benefits the ecophysiological performance of Caatinga plants during drought. [ABSTRACT FROM AUTHOR]

Stomata are pores on plant aerial surfaces, each bordered by a pair of guard cells. They control gas exchange vital for plant survival. Understanding how guard cells respond to environmental signals such as atmospheric carbon dioxide (CO2) levels is not only insightful to fundamental biology but also relevant to real-world issues of crop productivity under global climate change. In the past decade, multiple important signaling elements for stomatal closure induced by elevated CO2 have been identified. Yet, there is no comprehensive understanding of high CO2-induced stomatal closure. In this work, we assemble a cellular signaling network underlying high CO2-induced stomatal closure by integrating evidence from a comprehensive literature analysis. We further construct a Boolean dynamic model of the network, which allows in silico simulation of the stomatal closure response to high CO2 in wild-type Arabidopsis thaliana plants and in cases of pharmacological or genetic manipulation of network nodes. Our model has a 91% accuracy in capturing known experimental observations. We perform network-based logical analysis and reveal a feedback core of the network, which dictates cellular decisions in closure response to high CO2. Based on these analyses, we predict and experimentally confirm that applying nitric oxide (NO) induces stomatal closure in ambient CO2 and causes hypersensitivity to elevated CO2. Moreover, we predict a negative regulatory relationship between NO and the protein phosphatase ABI2 and find experimentally that NO inhibits ABI2 phosphatase activity. The experimental validation of these model predictions demonstrates the effectiveness of network-based modeling and highlights the decision-making role of the feedback core of the network in signal transduction. We further explore the model's potential in predicting targets of signaling elements not yet connected to the CO2 network. Our combination of network science, in silico model simulation, and experimental assays demonstrates an effective interdisciplinary approach to understanding system-level biology. Stomata are pores on plant surfaces that can be opened or closed by pairs of guard cells in response to environmental signals. This study analyzes CO2-induced stomatal closure in Arabidopsis thaliana using network-based modelling and experimental validation, uncovering that feedback loops in a core signal transduction network regulate decision-making in guard cells. [ABSTRACT FROM AUTHOR]

The current investigation demonstrates that the application of MEL (0, 1, and 2 μmol L−1) mitigates the effects of Cr stress 0 (no Cr), 50 and 100 mg kg−1 on coriander (Coriandrum sativum L.) plants. Results from the present study showed that the increasing levels of Cr concentration in the soil induced a significant decrease in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid contents, net photosynthesis, transpiration rate and stomatal conductance by 36%, 24%, 17%, 64%, 27%, 23%, 19%, 29%, 36%, 18%, 73%, 83%, and 43% respectively. Results findings also showed that the increasing Cr stress in the soil significantly (p< 0.05) decreases calcium, magnesium, iron, and phosphorus contents by 69%, 51%, 89%, and 109% respectively in the roots and decreased by 164%, 97%, 66%, and 124% respectively in the shoots. However, Cr toxicity boosted the production of reactive oxygen species (ROS) by increasing the contents of oxidative stress indicators. Although activities of various antioxidative enzymes and their specific gene expression and also the nonenzymatic antioxidants initially increased up to a Cr level of 50 μM but decreased gradually with the further increase in the Cr level of 100 μM in the medium, compared to those plants which were grown in the control treatment. Results also revealed that the soluble sugar, reducing sugar, and nonreducing sugar were decreased in plants grown under elevating Cr levels but increased the Cr accumulation in the roots and shoots of C. sativum. Although results also illustrated that the application of MEL also decreased Cr toxicity in C. sativum by increasing antioxidant capacity and their gene expression and thus improved the plant growth, photosynthetic pigments, and decrease oxidative stress in the roots and shoots of C. sativum. [ABSTRACT FROM AUTHOR]

Hops are grown mainly for the brewing market due to the rich chemical composition that gives beer aroma and bitterness. Brazil is one of the largest beer producers and consumers in the world and one of the largest hop importers. There is growing demand and interest in producing hops for domestic supply; however, as this crop originates from a temperate climate and the Northern Hemisphere, it is important to carry out research that describes the development of hops in a tropical climate to provide information on its cultivation in Brazil, as well as to determine its behavior in organic cultivation. A randomized block design was adopted, the treatments consisted of two cropping systems, conventional and organic, for Hallertau Mittelfrueh variety cultivation, with four blocks and three plants per plot. Gas exchange analyzes of plants under both cultivation systems were performed to obtain measurements of A, gs, Ci, E, WUE and A/Ci, morphometric and yield analyzes were also carried out. In comparison with the plants of the organic system, the plants of the conventional cultivation had greater photosynthetic efficiency; however, the practices adopted in the organic cultivation system provided the plants with greater productive capacity. [ABSTRACT FROM AUTHOR]

The success of immediate adaptation to extrauterine life depends on appropriate lung function, however, elective cesarean section can increase the risk of respiratory distress as a result of reduced pulmonary fluid absorption. This study aimed to evaluate the influence of birth mode on pulmonary clearance and respiratory performance of canine neonates in the transition period. For this purpose, 37 neonates were selected according to the obstetric condition: Vaginal Eutocia (n = 17) and Elective C-section (n = 20). Neonates were evaluated for neonatal vitality score, as well as evaluation of heart and respiratory rates, body temperature and body weight, venous hemogasometric evaluation, blood lactate and glucose, pulse oximetry and radiographic evaluation during the first 24 h of life. Additionally, amniotic fluid electrolyte composition of each puppy was evaluated. There was no influence of the type of delivery on electrolyte composition of canine amniotic fluid and neonatal pulmonary liquid content, analyzed by thoracic X-Rays. On the other hand, elective cesarean section delayed pulmonary adaptation, resulting in hypoxemia and less efficient compensatory response to acid-base imbalance and thermoregulation. In conclusion, elective c-section does not delay pulmonary clearance, whilst alters pulmonary adaptation by less efficient gas exchange and lower oxygenation, hindering the compensatory response to acid-base imbalance during the fetal-neonatal transition in dogs. • Elective c-section does not modify radiographic pulmonary content in puppies. • Elective c-section delays clinical pulmonary stabilization after birth in puppies. • Elective c-section hinders the compensatory response to acid-base imbalance. • Elective c-section delays pulmonary efficient gas exchange in puppies. [ABSTRACT FROM AUTHOR]

Summary: Theoretically, the PEP‐CK C4 subtype has a higher quantum yield of CO2 assimilation (ΦCO2) than NADP‐ME or NAD‐ME subtypes because ATP required for operating the CO2‐concentrating mechanism is believed to mostly come from the mitochondrial electron transport chain (mETC). However, reported ΦCO2 is not higher in PEP‐CK than in the other subtypes. We hypothesise, more photorespiration, associated with higher leakiness and O2 evolution in bundle‐sheath (BS) cells, cancels out energetic advantages in PEP‐CK species.Nine species (two to four species per subtype) were evaluated by gas exchange, chlorophyll fluorescence, and two‐photon microscopy to estimate the BS conductance (gbs) and leakiness using a biochemical model.Average gbs estimates were 2.9, 4.8, and 5.0 mmol m−2 s−1 bar−1, and leakiness values were 0.129, 0.179, and 0.180, in NADP‐ME, NAD‐ME, and PEP‐CK species, respectively. The BS CO2 level was somewhat higher, O2 level was marginally lower, and thus, photorespiratory loss was slightly lower, in NADP‐ME than in NAD‐ME and PEP‐CK species. Differences in these parameters existed among species within a subtype, and gbs was co‐determined by biochemical decarboxylating sites and anatomical characteristics.Our hypothesis and results partially explain variations in observed ΦCO2, but suggest that PEP‐CK species probably use less ATP from mETC than classically defined PEP‐CK mechanisms. [ABSTRACT FROM AUTHOR]

Crown rot (CR; Fusarium pseudograminearum) is a serious disease in winter cereals. Soil type, temperature, nutrients, water availability and stubble‐borne inoculum levels play major roles in determining disease severity. This paper reports the impact of two different watering regimes on the disease severity and gas exchange of F. pseudograminearum infected bread wheat for the first time. Fusarium pseudograminearum inoculated and noninoculated genotypes with different susceptibility to CR were watered to either field capacity or a reduced watering regime in three controlled environment experiments. Rate of photosynthesis, stomatal conductance, internal CO2 concentration and transpiration rate were measured using a portable photosynthesis system, together with disease severity of leaf sheaths at 28 days after planting. Significant differences in disease severity were reported between watering treatments with reduction in CR symptoms in the partially resistant genotypes in the reduced water treatment. Photosynthesis, stomatal conductance and transpiration rate were significantly decreased across most genotypes when inoculated with F. pseudograminearum. Differences in gas exchange between inoculum treatments were more evident in plants watered to field capacity. Water availability has been reported to be one of the crucial factors for initiating F. pseudograminearum infection and subsequent development of CR disease. This research demonstrates significant variation in genotype‐related responses to the complex interactions of F. pseudograminearum infection and water treatment, with a negative impact of both limited soil water availability and CR disease severity on plant gas exchange in bread wheat. [ABSTRACT FROM AUTHOR]

Stomatal movement, initiated by specialized epidermal cells known as guard cells (GCs), plays a pivotal role in plant gas exchange and water use efficiency. Despite protocols existing for isolating GCs through proplasting for carrying out biochemical, physiological, and molecular studies, protocals for isolating GCs with their cell walls still intact have been lacking in the literature. In this paper, we introduce a method for the isolation of complete GCs from Vicia faba and show their membrane to remain impermeable through propidium iodide staining. This methodology enables further in-depth analyses into the cell wall composition of GCs, facilitating our understanding of structure-function relationship governing reversible actuation within cells. [ABSTRACT FROM AUTHOR]

Summary: The strong covariation of temperature and vapour pressure deficit (VPD) in nature limits our understanding of the direct effects of temperature on leaf gas exchange. Stable isotopes in CO2 and H2O vapour provide mechanistic insight into physiological and biochemical processes during leaf gas exchange.We conducted combined leaf gas exchange and online isotope discrimination measurements on four common European tree species across a leaf temperature range of 5–40°C, while maintaining a constant leaf‐to‐air VPD (0.8 kPa) without soil water limitation.Above the optimum temperature for photosynthesis (30°C) under the controlled environmental conditions, stomatal conductance (gs) and net photosynthesis rate (An) decoupled across all tested species, with gs increasing but An decreasing. During this decoupling, mesophyll conductance (cell wall, plasma membrane and chloroplast membrane conductance) consistently and significantly decreased among species; however, this reduction did not lead to reductions in CO2 concentration at the chloroplast surface and stroma.We question the conventional understanding that diffusional limitations of CO2 contribute to the reduction in photosynthesis at high temperatures. We suggest that stomata and mesophyll membranes could work strategically to facilitate transpiration cooling and CO2 supply, thus alleviating heat stress on leaf photosynthetic function, albeit at the cost of reduced water‐use efficiency. [ABSTRACT FROM AUTHOR]

Concerns are repeatedly raised about possible adverse respiratory effects of wearing filtering face pieces (FFP) during physical activity. This study compared the impact of FFP type 2 (NF95) on pulmonary function, blood gas values, metabolism and discomfort during light, moderate and vigorous physical activity. Healthy adults (n = 13; 6 females, 7 males; mean 31.3, SD 5.5 years) participated in this randomized two-armed (Ergometer cycling with a FFP type 2 vs. no mask) crossover trial. Baseline cardiopulmonary exercise testing and two interventions (masked and unmasked ergometer cycling 40%, 50% and 70% VO2max, 10 min each) were separated by 48 h washout periods. Spiroergometric data (End tidal carbon dioxide partial pressure PetCO2; breathing frequency; inspiration time), blood gas analysis outcomes (capillary carbon dioxide partial pressure, pCO2) and subjective response (Breathing effort and perceived exertion) were contrasted between conditions using ANOVAs. All participants completed the crossover trial, seven started with the FFP2 condition (No adverse events or side effects). FFP2 decreased breathing frequency, prolonged inspiration time, increased perceived breathing effort and PetCO2 (p <.05). Blood pCO2 in millimetres mercury increased during exercise with 50%VO2max (mean 36.67, SD 3.19 vs. mean 38.46, SD 2.57; p <.05) and 70%VO2max (35.04, 2.84 vs. 38.17, 3.43; p <.05) but not during exercise with 40%VO2max (36.55, 2.73 vs. 38.70). Perceived exertion was not affected (p > 0.05) by mask wearing. Conclusion: Mask-induced breathing resistance decreased respiratory performance and limited pulmonary gas exchange. While FFP2 affected subjective breathing effort per se, invasive diagnostics showed that statistically significant metabolic effects are induced from moderate intensity upwards. Trial registration: DRKS-ID: DRKS00030181, Date of registration: 05/09/2022 (German Register for Clinical Trials). [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the morpho-physiological responses of tomato and bell pepper plants when specific nutrients were restricted. The study was conducted in a greenhouse under controlled environmental conditions and used hydroponic solution as the growth medium, with the nutrient solution being replaced as needed. Treatments consisted of a control treatment that included all nutrients at optimal concentrations and the suppression of magnesium (Mg), boron (B), zinc (Zn), and iron (Fe) for both tomato and bell pepper. The experimental design followed a completely randomized design, with a 2 (crops) × 5 (treatments) factorial scheme replicated four times. The results of this study showed that suppression of Fe had the most pronounced negative effect on the morphology and physiology of tomatoes and bell peppers and caused a reduction in parameters associated with gas exchange, leading to the development of interveinal chlorosis in the leaves. The suppression of Mg had the second most notable negative effects, with similar deficiency symptoms observed in the plant leaves as observed for the absence of Fe. While the suppression of B and Zn were less prominent compared to Fe and Mg, they still resulted in tissue malformation in the shoot apices and reductions in gas exchange and negatively impacted the morphological parameters evaluated. Therefore, our study provided important insights on how Mg, B, Zn, and Fe depletion affects tomato and bell pepper physiology and its impacts on tomato and bell pepper morphology. [ABSTRACT FROM AUTHOR]

Whiteflies cause significant crop losses through direct sap feeding, inducing plant physiological disorders and promoting the growth of sooty mold. Moreover, whiteflies can indirectly harm plants by transmitting plant viruses, particularly begomoviruses and criniviruses, resulting in severe viral disease epidemics. This study aimed to evaluate the physiological characteristics of susceptible and resistant soybean cultivars to B. tabaci. The experiments were conducted in a greenhouse. Eleven soybean cultivars were selected and infested with 100 adults of B. tabaci at the V3 stage. The evaluation of photosynthetic parameters, such as photosynthetic rate, leaf transpiration, stomatal conductance, and internal CO2 concentration, revealed that B. tabaci infestation influenced gas exchange in soybean plants. The photosynthetic rate was higher in cultivars AS3810 and M8349 during the V6 stage. Infestations caused alterations in photosynthetic parameters, suggesting increased energy demand to maintain photosynthetic activity. However, the response to infestation varied among the different cultivars, indicating varying levels of resistance and tolerance to the whitefly's damage. Furthermore, the infestation had a more notable impact during the vegetative phenological stage. In summary, infestation by B. tabaci has a discernible impact on the physiology of soybean plants, resulting in alterations in gas exchange parameters and water use efficiency. The reaction to infestation exhibited variations among different soybean cultivars, indicating potential differences in resistance to the pest. This study underscores the significance of assessing the physiological consequences of whitefly infestations on soybean crops. [ABSTRACT FROM AUTHOR]

This article discusses the importance of phenotyping photosynthesis for crop improvement and breeding programs. The authors highlight the challenges of studying photosynthesis in natural conditions and the need for higher throughput tools to overcome these barriers. They discuss the use of controlled-environment systems and remote sensing methods, such as solar-induced fluorescence and laser/light-induced fluorescence transient, for phenotyping photosynthesis. The authors also mention the use of hand-held MultispeQ PAM fluorometers as affordable tools for field phenotyping. The article concludes by emphasizing the potential of photosynthetic phenotyping for driving yield improvement in crop breeding programs. [Extracted from the article]

Background: Salinity stress affects crop yields worldwide. Mungbean, a popular grain legume with protein-rich seeds, is glycophytic and vulnerable to saline stress. Silicon has become a key ingredient that boosts plant enzymatic antioxidant activity and osmoprotectant synthesis, promoting stress tolerance. Methods: In chloride-dominated salinity conditions of 4 and 6 dSm-1, sodium meta-silicate administration strategies were examined in salt-affected mungbean (MH421). Two application strategies were used: foliar spraying at 50 mg/l and 100 mg/l at 30 and 45 DAS and soil addition at 50 mg/kg soil as a solution during planting. The effects of these treatments were examined at 33 and 48 DAS, three days following foliar sodium meta-silicate application. Result: Salinity stress reduced dry weight, nodule counts, gas exchange characteristics and plant water relation features, although Si treatment buffered the detrimental effect to a varied amount. Best effects were obtained with 100 ppm foliar application. Lipid peroxidation and electrolyte loss increased with salinity stress, while Si reduces these losses by scavenging free radicals. Silicon supplementation lowered Na+ and increased K+ absorption. Also, Si altered photosynthetic machinery, Na+/K+ homeostasis, osmolyte synthesis and oxidative stress in mungbean to reduce salinity stress and increase seed yield. [ABSTRACT FROM AUTHOR]

Summary: Stomata are epidermal pores that facilitate plant gas exchange. Grasses have fast stomatal movements, likely due to their dumbbell‐shaped guard cells and lateral subsidiary cells. Subsidiary cells reciprocally exchange water and ions with guard cells. However, the relative contribution of subsidiary cells during stomatal closure is unresolved.We compared stomatal gas exchange and stomatal aperture dynamics in wild‐type and pan1, pan2, and pan1;pan2 Zea mays (L.) (maize) mutants, which have varying percentages of aberrantly formed subsidiary cells. Stomata with 1 or 2 defective subsidiary cells cannot close properly, indicating that subsidiary cells are essential for stomatal function.Even though the percentage of aberrant stomata is similar in pan1 and pan2, pan2 showed a more severe defect in stomatal closure. In pan1, only stomata with abnormal subsidiary cells fail to close normally. In pan2, all stomata have stomatal closure defects, indicating that PAN2 has an additional role in stomatal closure.Maize Pan2 is orthologous to Arabidopsis GUARD CELL HYDROGEN PEROXIDE‐RESISANT1 (GHR1), which is also required for stomatal closure. PAN2 acts downstream of Ca2+ in maize to promote stomatal closure. This is in contrast to GHR1, which acts upstream of Ca2+, and suggests the pathways could be differently wired. [ABSTRACT FROM AUTHOR]

Penstemons are a diverse group of flowering plants valued for their ability to enhance the visual appearance of urban landscapes. Penstemon barbatus (Cav.) Roth 'Novapenblu' (rock candy blueVR penstemon) and Penstemon strictus Benth 'Rocky Mountain' (rocky mountain beardtongue) are widely used in landscapes, but their tolerance to soil salinity remains poorly understood. This study aimed to investigate the effects of salinity levels at electrical conductivities (ECs) of 1.0 (nutrient solution), 2.5, 5.0, 7.5, and 10.0 dS·m21 on two penstemons (P. barbatus and P. strictus). Penstemons were irrigated with nutrient or saline solution for 8 weeks and various growth and physiological data were recorded before harvest. Salinity stress degraded the visual quality of penstemon species and led to a reduction in the growth rate and biomass production. Leaf burn and necrosis were observed in penstemons because of salinity stress. The visual score of P. barbatus and P. strictus decreased with increasing EC levels in the saline solution. When irrigated with saline solution at an EC of 7.5 dS·m21, Penstemon barbatus and P. strictus had severe-to-moderate foliar salt damage with average visual scores of 1.7 and 2.5, respectively (0 5 dead plant; 5 5 excellent plant without any foliar damage). The two penstemon species had severe foliar salt damage or were dead when irrigated with saline solution at an EC of 10.0 dS·m21. There were 87% and 92% decreases in the leaf area of P. barbatus and P. strictus, respectively, when irrigated with saline solution at an EC of 10.0 dS·m21 compared with those in the control. Although not statistically significant, there were 7% to 18% decreases in shoot dry weight of P. barbatus when irrigated with saline solutions at ECs of 2.5 to 10.0 dS·m21 compared with control. However, P. strictus displayed declines of 13% to 31% in shoot dry weight as the salinity levels of the irrigation solution increased. As the salinity levels increased, the net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration (E) rates decreased. Furthermore, sodium (Na+) and chloride (Cl2) contents of P. barbatus and P. strictus increased with the increase in salinity levels of the treatment solution. Consequently, P. barbatus and P. strictus demonstrated sensitivity to salinity stress at ECs of 7.5 and 10.0 dS·m21. This study provides important insights for their effective utilization in landscaping practices within saline-prone areas. [ABSTRACT FROM AUTHOR]

Viscum schimperi is an evergreen hemiparasitic plant that can grow on stems and branches of several tree species. It penetrates the host tissues and forms a vascular bridge (haustorium) to withdraw the nutritive resources. Its relationships with hosts remain unknown. This study aimed to investigate the physiological and biochemical attributes of the host-hemiparasite association Acacia gerrardii-Viscum schimperi. The hemiparasite exhibited 2.4- and 3.0-fold lower photosynthetic activity and water use efficiency, and 1.2- and 4.1-fold higher transpiration rate and stomatal conductance. Equally, it displayed 4.9- and 2.6-fold greater water potential and osmotic potential, and in least 3.0 times more accumulated 39K, 85Rb and 51V, compared to the host. Nevertheless, it had no detrimental effect on photosynthetic activity, water status and multi-element accumulations in the host. Based on metabolome profiling, V. schimperi could use xanthurenic acid and propylparaben to acquire potassium from the host, and N-1-naphthylacetamide and N-Boc-hydroxylamine to weaken or kill the distal part of the infected branch and to receive the total xylem contents. In contrast, A. gerrardii could used N-acetylserotonin, arecoline, acetophenone and 6-methoxymellein to defend against V. schimperi infection. [ABSTRACT FROM AUTHOR]

Rising temperatures pose a threat to the stability of climate regulation by carbon metabolism in subtropical forests. Although the effects of temperature on leaf carbon metabolism traits in sun-exposed leaves are well understood, there is limited knowledge about its impacts on shade leaves and the implications for ecosystem–climate feedbacks. In this study, we measured temperature response curves of photosynthesis and respiration for 62 woody species in summer (including both evergreen and deciduous species) and 20 evergreen species in winter. The aim was to uncover the temperature dependence of carbon metabolism in both sun and shade leaves in subtropical forests. Our findings reveal that shade had no significant effects on the mean optimum photosynthetic temperatures (TOpt) or temperature range (T90). However, there were decreases observed in mean stomatal conductance, mean area-based photosynthetic rates at TOpt and 25 °C, as well as mean area-based dark respiration rates at 25 °C in both evergreen and deciduous species. Moreover, the respiration–temperature sensitivity (Q10) of sun leaves was higher than that of shade leaves in winter, with the reverse being true in summer. Leaf economics spectrum traits, such as leaf mass per area, and leaf concentration of nitrogen and phosphorus across species, proved to be good predictors of TOpt, T90, mass-based photosynthetic rate at TOpt, and mass-based photosynthetic and respiration rate at 25 °C. However, Q10 was poorly predicted by these leaf economics spectrum traits except for shade leaves in winter. Our results suggest that model estimates of carbon metabolism in multilayered subtropical forest canopies do not necessitate independent parameterization of T90 and TOpt temperature responses in sun and shade leaves. Nevertheless, a deeper understanding and quantification of canopy variations in Q10 responses to temperature are necessary to confirm the generality of temperature–carbon metabolism trait responses and enhance ecosystem model estimates of carbon dynamics under future climate warming. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the alterations in physiological, biochemical, and transcriptional reactions in the flag leaf of rice following the application of Trichoderma as a biofertilizer (BF) at both ambient (aCO2; 395 ppm) and enhanced (eCO2; 550 ppm) carbon dioxide levels. A comparatively smaller percentage change was observed in the photosynthetic parameters, including photosynthetic rate, respiration, and stomatal conductance, subsequent to the introduction of BF in the elevated carbon dioxide (eCO2) environment. Furthermore, biochemical analysis revealed a noteworthy elevation in photosynthetic pigments, total sugar, proline, and ascorbate peroxidase concentration levels in plants treated with BF under ambient and increased carbon dioxide conditions. The buildup of indole‐3‐acetic acid (IAA) was shown to be increased in rice treated with BF under both conditions. Moreover, ICP‐MS analysis demonstrated an augmentation in the levels of vital micronutrients in the experimental group while observing no alterations in the carbon‐to‐nitrogen ratio within the flag leaf. The examination of transcriptional responses in the flag leaf demonstrated an increase in the expression of genes associated with the photosynthetic system, amino acid metabolism, several transporters, including aquaporin, and the phosphate pathway, as well as carbon and nitrogen metabolism. Hence, our work elucidates the effective role of Trichoderma in mitigating the adverse consequences associated with elevated levels of atmospheric carbon dioxide (eCO2). [ABSTRACT FROM AUTHOR]

Xylem transport is essential for the growth, development and survival of vascular plants. Bark wounding may increase the risk of xylem transport failure by tension-driven embolism. However, the consequences of bark wounding for xylem transport are poorly understood. Here, we examined the impacts of the bark wounding on embolism formation, leaf water potential and gas exchange in the terminal branches of two diffuse-porous tree species (Acer platanoides L. and Prunus avium L.). The effects of bark removal were examined on field-grown mature trees exposed to increased evaporative demands on a short-term and longer-term basis (6 h vs 6 days after bark wounding). Bark removal of 30% of branch circumference had a limited effect on the xylem hydraulic conductivity when embolized vessels were typically restricted to the last annual ring near the bark wound. Over the 6-day exposure, the non-conductive xylem area had significantly increased in the xylem tissue underneath the bark wound (from 22–29% to 51–52% of the last annual ring area in the bark wound zone), pointing to gradual yet relatively limited embolism spreading to deeper xylem layers over time. In both species, the bark removal tended to result in a small but non-significant increase in the percent loss of hydraulic conductivity compared with control intact branches 6 days after bark wounding (from 6 to 8–10% in both species). The bark wounding had no significant effects on midday leaf water potential, CO2 assimilation rates, stomatal conductance and water-use efficiency of the leaves of the current-year shoot, possibly due to limited impacts on xylem transport. The results of this study demonstrate that bark wounding induces limited but gradual embolism spreading. However, the impacts of bark wounding may not significantly limit water delivery to distal organs and leaf gas exchange at the scale of several days. [ABSTRACT FROM AUTHOR]

Root pruning hinders the absorption and utilization of nutrients and water by seedlings in the short term. Arbuscular mycorrhizal fungi (AMF) are an important source of nutrient and water for seedlings except for the root system. However, the mechanism by which AMF affect the physiological growth of seedlings after root pruning has rarely been studied. In this study, a pot experiment was conducted through a three-compartment partition system to clarify the effects of Funneliformis mosseae (F. mosseae) strain BGC XJ07A on the physiological growth of root-pruned Robinia pseudoacacia seedlings. Five root pruning treatments (zero, one-fifth, one-fourth, one-third and one-half of the taproot length were removed) were applied to noninoculated seedlings and those inoculated with F. mosseae. The results showed that the presence of F. mosseae significantly increased the shoot and root biomasses, leaf photosynthetic rate, stomatal conductance and transpiration rate. The root projected area, root surface area, average root diameter, root density, root volume and number of root tips of the inoculated seedlings were higher than those without inoculation in all root pruning treatments. The root cytokinin, gibberellins and indole-3-acetic acid concentrations, but root abscisic acid concentration, were higher than those measured in the absence of inoculation in all root pruning treatments. Moreover, the changes in the root endogenous hormone concentrations of the seedlings were closely related to the root morphological development and seedling biomass. The AMF increased the soil available nitrogen, soil available phosphorus, soil available potassium and soil organic matter concentrations compared with the noninoculated treatment. These results indicate that AMF can alleviate the adverse effects of root pruning on the physiological growth of R. pseudoacacia and soil properties, and can provide a basis for AMF application to forest cultivation and the sustainable development of forest ecosystems. [ABSTRACT FROM AUTHOR]

To clarify the physiological mechanism of different groundwater depths affecting soybean evapotranspiration, photosynthetic characteristics and yield, a field experiment with four groundwater depth levels (1 m (D1), 2 m (D2), 3 m (D3) and 4 m (D4)) was conducted through the groundwater simulation system in 2021 and 2022. In this study, a quantitative analysis was conducted on the groundwater recharge and irrigation water demand and evapotranspiration (ET) of soybean fields with different treatments, and the effects of different treatments on soybean leaf area index (LAI), chlorophyll content index (SPAD), intercepted photosynthetic active radiation (IPAR), photosynthetic gas exchange parameters, dry matter accumulation (DMA) and yield were explored. The results showed the following: (1) Groundwater depth affected soybean ET and the source of ET. With the increase in groundwater depth, groundwater recharge and its contribution to ET gradually decreased, but the amount of irrigation required gradually increased, resulting in the ET as D1 > D4 > D2 > D3. (2) Soybean LAI, SPAD and IPAR were significantly affected by the different groundwater depths, of which the D1 treatment always maintained the maximum, followed by the D4 treatment, and the D3 treatment was the minimum. The photosynthetic gas exchange parameters under different treatments changed synergistically, showing significant differences in the flowering and podding stages, notably D1 > D4 > D2 > D3. Soybean DMA and yield first decreased and then increased with the increase in groundwater depth, and the average DMA and yield under the D1 treatment increased by 27.71%, 46.80% and 22.82% and 20.29%, 29.91% and 12.83% in the two years, respectively, compared to the D2, D3 and D4 treatments. (3) The structural equation model demonstrated that the groundwater depth indirectly affected the growth of soybean leaf area by affecting groundwater recharge, which in turn regulated soybean ET and photosynthetic capacity and ultimately affected DMA and yield. The above results showed that in the case of shallow groundwater depth (D1), the largest groundwater recharge promoted the growth of soybean leaf area and chlorophyll synthesis and increased the absorption and utilization of solar radiation. And it improved the leaf stomata conditions, accelerated the gas exchange between the plant and atmosphere, enhanced the photosynthetic production capacity and ET and achieved maximum DMA and yield. Soybean leaf growth and photosynthesis diminish with the increase in groundwater depth. In the case of deep groundwater depth (D4), the maximum irrigation improved the growth and photosynthetic performance of soybean leaves, which was favorable to ET, and ultimately led to increases in DMA and yield. [ABSTRACT FROM AUTHOR]

Water stress can trigger acclimation responses and damage plants. The aim of this study was to evaluate the integrative responses of cotton hydraulic conductance, leaf photosynthesis, and carbon metabolism to short-term drought and subsequent rewatering. A water-controlled pot experiment was conducted in 2020, with soil water drying continuing for one day (D1), two days (D2), and three days (D3) after it reached 40% ± 5% of the soil water holding capacity at the blooming stage of cotton, and the soil was then rewatered to the soil water holding capacity. We investigated how the stem hydraulic conductance, gas exchange, and biochemical traits of cotton were affected by imposed drought stress and subsequent rewatering. The hydraulic characteristics of cotton in the D2 and D3 treatments evolved with damage, complete closure of stomatal conductance, and complete deterioration of photosynthesis, in addition to severe floating changes in the carbon metabolism affected by drought. The leaves' functional characteristics after rewatering cannot be completely recovered to full-irrigation levels, and the recovery extent was strongly linked to the duration. Consequently, it is considered desirable to maintain normal physiological activity during the cotton reproductive period, and the drought episode can be sustained for 1 day in a long-term perspective when the soil water content is depleted to 40% ± 5% of the soil water holding capacity. These results can provide in-depth ideas for better understanding the hydraulic and physiological responses of cotton to drought episodes and rewatering, and they can help drought-affected cotton to cope with future climate change. [ABSTRACT FROM AUTHOR]

Neutrophils play a dual role in protecting the body. They are able to penetrate infected tissues and destroy pathogens there by releasing aggressive bactericidal substances. While into the surrounding tissues, the aggressive products secreted by neutrophils initiate development of inflammatory processes. Invasion of neutrophils into tissues is observed during the development of pneumonia in the patients with lung diseases of various etiologies, including acute respiratory distress syndrome caused by coronavirus disease. Synthetic corticosteroid hormone dexamethasone has a therapeutic effect in treatment of lung diseases, including reducing mortality in the patients with severe COVID-19. The acute (short-term) effect of dexamethasone on neutrophil adhesion to fibrinogen and concomitant secretion was studied. Dexamethasone did not affect either attachment of neutrophils to the substrate or their morphology. Production of reactive oxygen species (ROS) and nitric oxide (NO) by neutrophils during adhesion also did not change in the presence of dexamethasone. Dexamethasone stimulated release of metalloproteinases in addition to the proteins secreted by neutrophils during adhesion under control conditions, and selectively stimulated release of free amino acid hydroxylysine, a product of lysyl hydroxylase. Metalloproteinases play a key role and closely interact with lysyl hydroxylase in the processes of modification of the extracellular matrix. Therapeutic effect of dexamethasone could be associated with its ability to reorganize extracellular matrix in the tissues by changing composition of the neutrophil secretions, which could result in the improved gas exchange in the patients with severe lung diseases. [ABSTRACT FROM AUTHOR]

Background: The leaf epidermis plays an important role in the transmission of light and the regulation of water and gas exchange, which influences the photosynthesis of mesophyll cells. Small papillae (SP) are one of the important structural elements of the leaf epidermis. The mechanism of the effect that small papillae have on rice leaf photosynthetic performance remains unclear. Results: In this study, a small papilla deficient 25 (spd25) mutant was isolated from japonica rice Longjin1. Small papillae were absent on the adaxial and abaxial leaf surfaces of the spd25 mutant and the silicon and cuticular wax content in the spd25 mutant leaves decreased. Map-based cloning and functional analysis revealed that SPD25, encoding a guanine nucleotide exchange factor for Rop, is a novel allele of OsRopGEF10. The spd25 mutant showed an increased water loss rate and reduced relative water content. The lower stomatal conductance in the spd25 mutant prevented water loss but decreased the intercellular CO2 concentration and net assimilation rate. The fluorescence parameters showed that the inhibited CO2 assimilation reaction feedback regulated the photochemical electron-transfer reaction, but the performance of Photosystem II was stable. Further analysis indicated that the excess light energy absorbed by the spd25 mutant was dissipated in the form of non-photochemical quenching to avoid photodamage through the optical properties of small papillae. Conclusions: SPD25 regulates the development of small papillae on the surface of rice leaves, which play an important role in balancing photosynthetic gas exchange and water loss. This study deepens our understanding of the physiological mechanisms by which small papillae affect photosynthetic performance. [ABSTRACT FROM AUTHOR]

Grape rain-shelter cultivation is a widely employed practice in China. At present, the most commonly used rain shelter film materials are polyvinyl chloride (PVC), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), and polyolefin (PO). Coverlys TF150® is a woven fabric with an internal antifoggy PE coating that has not yet been popularized as a rain shelter film for grapes in China. To investigate the effects of Coverlys TF150® on grapes, we measured the microdomain environment, leaf development, and photosynthetic characteristics of 'Miguang' (Vitis vinifera × V. labrusca) under rain-shelter cultivation and performed transcriptome analysis. The results showed that Coverlys TF150® significantly reduced (p < 0.05) the light intensity, temperature, and humidity compared with PO film, increased the chlorophyll content and leaf thickness (particularly palisade tissue thickness), and increased stomatal density and stomatal opening from 10:00 to 14:00. Coverlys TF150® was observed to improve the maximum efficiency of photosystem II (Fv/Fm), photochemical quenching (qP), the electron transfer rate (ETR), and the actual photochemical efficiency (ΦPSII) from 10:00 to 14:00. Moreover, the net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), and transpiration rate (Tr) of grape leaves significantly increased (p < 0.05) from 10:00 to 14:00. RNA-Seq analysis of the grape leaves at 8:00, 10:00, and 12:00 revealed 1388, 1562, and 1436 differential genes at these points in time, respectively. KEGG enrichment analysis showed the occurrence of protein processing in the endoplasmic reticulum. Plant hormone signal transduction and plant-pathogen interaction were identified as the metabolic pathways with the highest differential gene expression enrichment. The psbA encoding D1 protein was significantly up-regulated in both CO10vsPO10 and CO12vsPO12, while the sHSPs family genes were significantly down-regulated in all time periods, and thus may play an important role in the maintenance of the photosystem II (PSII) activity in grape leaves under Coverlys TF150®. Compared with PO film, the PSI-related gene psaB was up-regulated, indicating the ability of Coverlys TF150® to better maintain PSI activity. Compared with PO film, the abolic acid receptacle-associated gene PYL1 was down-regulated at all time periods under the Coverlys TF150® treatment, while PP2C47 was significantly up-regulated in CO10vsPO10 and CO12vsPO12, inducing stomatal closure. The results reveal that Coverlys TF150® alleviates the stress of high temperature and strong light compared with PO film, improves the photosynthetic capacity of grape leaves, and reduces the midday depression of photosynthesis. [ABSTRACT FROM AUTHOR]

Lippia alba is one of the most used species in traditional medicine, having been the subject of intense exploration in search of the extraction of its essential oil, which contains several compounds of pharmacological importance. This study evaluated the effects of different concentrations of two biotic elicitors: yeast extract (YE) (0, 1, 2 and 4 g L−1) and chitosan (CH) (0, 1, 2 and 4 g L−1) in the accumulation of biomass, gas exchange, antioxidative system response, and production and profile of bioactive compounds (BCs). Foliar spraying with 4 g L−1 of CH favored the accumulation of shoot dry biomass and significantly increased the levels of chlorophyll a and carotenoids. Both elicitors were efficient to increase the essential oil content extracted from the leaves of L. alba and, in general, the elicitors tested at concentrations of 2 and 4 g L−1 showed the highest amounts of BCs and glandular trichome density. Chemical analysis of BCs revealed 46 different compounds, with Geranial and Geraniol being the main components. The application of YE induced the production of an exclusive compound (Trans-piperitol), while CH induced the formation of seven exclusive compounds (Santolina triene, Myrcenol, Neral, Cis-Pinocarvyl acetate, Dimethoxy-(Z)-citral, Geranyl acetate and Limonene aldehyde). Yeast extract and Chitosan proved to be efficient to increase the BCs content in Lippia alba , however, the application of 4 g L−1 of CH resulted in a higher production of shoot dry biomass, photosynthetic parameters, in the density of glandular trichomes and in the production of BCs. [Display omitted] [ABSTRACT FROM AUTHOR]

Crops are constantly threatened by salinity. Nitric oxide (NO) is an attenuating agent for salt stress; however, the specific roles of NO in gas exchange and lettuce production are not well established. The objective of this study was to evaluate the application of different concentrations of sodium nitroprusside (SNP) as an agent to mitigate salt stress in lettuce plants. Lettuce seedlings in pots were subjected to irrigation without and with saline water (0.2 and 3.5 dS m−1) and applications of different concentrations (0, 50, 100, 150, and 200 µM) of SNP, a NO donor. Saline stress negatively affected lettuce development with a reduction of 29.5% in leaf area, 6.3% in relative water content in the leaf, 17.2% in stem diameter, and 10.7% in dry matter mass in the control, but the application of SNP mitigated the deleterious effects of salt stress. Concentrations between 100 and 150 µM of SNP improved the photosynthetic metabolism of lettuce under salinity, with an increase of 46.7% in CO2 assimilation and 42.3% in fresh matter mass. Pearson's correlation showed that fresh matter correlated positively with CO2 assimilation. Therefore, SNP can be used to mitigate salt stress in lettuce. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated dose-responses of the cannabis plant to supply of macronutrients. However, further development of precision nutrition requires a high-resolution understanding of temporal trends of plant requirements for nutrients throughout the developmental progression, which is currently not available. As plant function changes during development, temporal information on nutrient uptake should be considered in relation to gradients in developmental-related physiological activity. Therefore, the present study investigated tempo-developmental trends of nutritional demands in cannabis plants, and in relation to physiological performance. Three cultivars differing in phenotype and chemotype were analyzed to evaluate genotypic variability. The results demonstrate that nutrient acquisition and deposition rates change dramatically during plant development. Uptake of individual minerals generally increased with the progression of both vegetative and reproductive development and the increase in plant biomass, while the deposition rates into the plant demonstrated nutrient specificity. The average concentrations of N, P, and K in the shoots of the different cultivars were 2.33, 4.90, and 3.32 times higher, respectively, at the termination of the reproductive growth phase, compared to the termination of the vegetative growth phase. Surprisingly, the uptake of Ca was very limited during the second part of the reproductive growth phase for two cultivars, revealing a decrease in Ca demand at this late developmental stage. Root-to-shoot translocation of most nutrients, including P, K, Mg, Mn, and Zn, as well as Na, is higher during the reproductive than the vegetative growth phase, and Fe, Mn, Zn, Cu, and Na displayed very little root-to-shoot translocation. The physiological characteristics of the plants, including gas exchange parameters, membrane leakage, osmotic potential, and water use efficiency, changed over time between the vegetative and the reproductive phases and with plant maturation, demonstrating a plant-age effect. The revealed tempo-developmental changes in nutritional requirements of the cannabis plant are a powerful tool required for development of a nutritional protocol for an optimal ionome. [ABSTRACT FROM AUTHOR]

Simple Summary: Intrapartum mortality reaches high figures in piglets, and it has been seen that those born with low weight and those with low or failed vitality scores are the most prone. Caffeine is used to reduce cardiorespiratory problems in neonates, both humans and animals. For this reason, the decision was made to use different doses of caffeine in newborn piglets in this study, to define if its oral administration would help reduce this problem and what would be the optimal dose and time of administration. The following blood gas parameters were evaluated: pH, pO2, pCO2, HCO3, Ca++, glucose, and lactate, as well as superficial and rectal temperature at 1 h, 6 h, and 24 h after birth. It was concluded that the optimal dose of caffeine to improve the vitality score and reduce possible cardiorespiratory problems is 30 mg/kg orally. Intrapartum asphyxia, fetal hypoxia, and their consequences (e.g., acidosis, hypercapnia, hypoglycemia, and hypothermia) are the main factors related to physio-metabolic imbalances that increase neonatal mortality in piglets, particularly in piglets with low birthweight and low vitality scores. This study aimed to evaluate the effect of three different doses of caffeine (10, 20, and 30 mg/kg) administered orally to 480 newborn piglets with low birthweight and low vitality scores. Blood gas parameters (pH, pO2, pCO2, and HCO3−), physio-metabolic profile (Ca++, glucose, and lactate), and the thermal response assessed through infrared thermography in four thermal windows (ocular, auricular, snout, and hindlimb) and rectal temperature were evaluated during the first 24 h of life. Doses of 30 mg/kg resulted in significant differences at 24 h for all evaluated parameters, suggesting that caffeine administration improved the cardiorespiratory function and metabolic activity of piglets by reducing acidosis, restoring glycemia, and increasing surface and rectal temperature. In conclusion, caffeine at 30 mg/kg could be suggested as an appropriate dose to use in piglets with low birthweight and low vitality scores. Future research might need to study the presentation of adverse effects due to higher caffeine concentrations. [ABSTRACT FROM AUTHOR]

Numerous vital signs are reported in association with stress response assessment, but their application varies widely. This work provides an overview over methods for stress induction and strain assessment, and presents a multimodal experimental study to identify the most important vital signs for effective assessment of the response to acute mental stress. We induced acute mental stress in 65 healthy participants with the Mannheim Multicomponent Stress Test and acquired self-assessment measures (Likert scale, Self-Assessment Manikin), salivary α-amylase and cortisol concentrations as well as 60 vital signs from biosignals, such as heart rate variability parameters, QT variability parameters, skin conductance level, and breath rate. By means of statistical testing and a self-optimizing logistic regression, we identified the most important biosignal vital signs. Fifteen biosignal vital signs related to ventricular repolarization variability, blood pressure, skin conductance, and respiration showed significant results. The logistic regression converged with QT variability index, left ventricular work index, earlobe pulse arrival time, skin conductance level, rise time and number of skin conductance responses, breath rate, and breath rate variability (F1 = 0.82). Self-assessment measures indicated successful stress induction. α-amylase and cortisol showed effect sizes of -0.78 and 0.55, respectively. In summary, the hypothalamic-pituitary-adrenocortical axis and sympathetic nervous system were successfully activated. Our findings facilitate a coherent and integrative understanding of the assessment of the stress response and help to align applications and future research concerning acute mental stress. [ABSTRACT FROM AUTHOR]

Gas exchange across the stomatal pores of leaves is a focal point in studies of plant‐environmental relations. Stomata regulate atmospheric exchange with the inner air spaces of the leaf. They open to allow CO2 entry for photosynthesis and close to minimize water loss. Models that focus on the phenomenology of stomatal conductance generally omit the mechanics of the guard cells that regulate the pore aperture. The OnGuard platform fills this gap and offers a truly mechanistic approach with which to analyse stomatal gas exchange, whole‐plant carbon assimilation and water‐use efficiency. Previously, OnGuard required specialist knowledge of membrane transport, signalling and metabolism. Here we introduce OnGuard3e, a software package accessible to ecophysiologists and membrane biologists alike. We provide a brief guide to its use and illustrate how the package can be applied to explore and analyse stomatal conductance, assimilation and water use efficiencies, addressing a range of experimental questions with truly predictive outputs. Summary statement: OnGuard3e offers a truly mechanistic approach with which to analyse stomatal gas exchange, whole‐plant carbon assimilation and water‐use efficiency. The software package seamlessly connects whole‐plant gas exchange and photosynthesis with the microscopic mechanics of stomata and is accessible to ecophysiologists and membrane biologists alike. We provide a brief guide to its use and illustrate how the package can be applied to explore and analyse stomatal conductance, assimilation and water use efficiencies, addressing a range of experimental questions with truly predictive outputs. [ABSTRACT FROM AUTHOR]

The development of light emitting diodes (LED) gives new possibilities to use the light spectrum to manipulate plant morphology and physiology in plant production and research. Here, vegetative Chrysanthemum × morifolium were grown at a photosynthetic photon flux density of 230 μmol m−2 s−1 under monochromatic blue, cyan, green, and red, and polychromatic red:blue or white light with the objective to investigate the effect on plant morphology, gas exchange and metabolic profile. After 33 days of growth, branching and leaf number increased from blue to red light, while area per leaf, leaf weight fraction, flavonol index, and stomatal density and conductance decreased, while dry matter production was mostly unaffected. Plants grown under red light had decreased photosynthesis performance compared with blue or white light‐grown plants. The primary and secondary metabolites, such as organic acids, amino acids and phenylpropanoids (measured by non‐targeted metabolomics of polar metabolites), were regulated differently under the different light qualities. Specifically, the levels of reduced ascorbic acid and its oxidation products, and the total ascorbate pool, were significantly different between blue light‐grown plants and plants grown under white or red:blue light, which imply photosynthesis‐driven alterations in oxidative pressure under different light regimens. The overall differences in plant phenotype, inflicted by blue, red:blue or red light, are probably due to a shift in balance between regulatory pathways controlled by blue light receptors and/or phytochrome. Although morphology, physiology, and metabolism differed substantially between plants grown under different qualities of light, these changes had limited effects on biomass accumulation. [ABSTRACT FROM AUTHOR]

Forest species have their growth and metabolism affected, when they are exposed to conditions of water stress and one of the factors that contribute to water scarcity is climate change that increases over time. The objective of this work was to evaluate changes in gas exchange, carbon metabolism and biomass of Clusia grandiflora subjected to water deficit and evaluation periods. The experiment was carried out in a completely randomized design, in a 2 × 5 factorial scheme, with five replications, each as specified: two water conditions (control and water deficit) and five evaluation periods (0, 7, 14, 21 and 28 days). The variables related to gas exchange, carbon metabolism and biomass were evaluated. The design of the experiment was completely randomized. The relative water content did not differ between the control plants and those submitted to water deficit. While stem diameter, adventitious root length, adventitious root diameter and stem dry mass decreased, when plants were exposed to water deficit. The number of leaves, stem height, leaf area and fallen leaves reduced from day 14, in plants submitted to water deficit. There was a reduction in the hydraulic conductivity and in the water potential of the xylem in the leaf from day 7 on in plants under water deficit. Among the biochemical variables, starch and sucrose concentrations increased in plants under water stress from day 14 onwards. Water deficit negatively affected gas exchange, carbon metabolism and Clusia grandiflora biomass. [ABSTRACT FROM AUTHOR]

Identification of the breathing cycle forms the basis of any breath-by-breath gas exchange analysis. Classically, the breathing cycle is defined as the time interval between the beginning of two consecutive inspiration phases. Based on this definition, several research groups have developed algorithms designed to estimate the volume and rate of gas transferred across the alveolar membrane ("alveolar gas exchange"); however, most algorithms require measurement of lung volume at the beginning of the ith breath (VLi-1; i.e., the end-expiratory lung volume of the preceding i th breath). The main limitation of these algorithms is that direct measurement of VLi-1 is challenging and often unavailable. Two solutions avoid the requirement to measure VLi-1 by redefining the breathing cycle. One method defines the breathing cycle as the time between two equal fractional concentrations of lung expired oxygen (FO2) (or carbon dioxide; FCO2), typically in the alveolar phase, whereas the other uses the time between equal values of the FO2/FN2 (or FCO2/FN2) ratios [i.e., the ratio of fractional concentrations of lung expired O2 (or CO2) and nitrogen (N2)]. Thus, these methods identify the breathing cycle by analyzing the gas fraction traces rather than the gas flow signal. In this review, we define the traditional approach and two alternative definitions of the human breathing cycle and present the rationale for redefining this term. We also explore the strengths and limitations of the available approaches and provide implications for future studies. [ABSTRACT FROM AUTHOR]

Background and Aims: Phosphorus (P) is a restricting nutrient for crop productivity worldwide. P deficiency can lead to stunted growth and development, eventually affecting crop yield. But less is documented about the impact of P fertility on industrial hemp (Cannabis sativa L.) production in the low-P soils of south-western Australia. We aimed to investigate the effect of P rates on growth, physiology, rhizosphere carboxylate exudation, nutrient uptake and P-use efficiency in hemp. Methods: The study was conducted in a randomised complete block design with four P rates (0, 40, 80 and 120 mg P kg–1 dry soil) and three hemp varieties (Morpeth, Han FNQ and Fedora 17). Plants were grown and raised in a controlled-environment phytotron until harvested 35 days after sowing at vegetative growth stage (3rd to nth leaf pair). Results: Our results revealed a strong influence of treatment (P rate) on hemp growth, physiology, biomass, nutrient uptake and P-use efficiency compared to variety and the variety × treatment interaction. Hemp roots predominantly released citrate in P-deficient conditions and gradually shifted to malate exudation with increasing P supply. The N:P ratio, leaf chlorophyll, and gas exchange data coupled with shoot and root length data suggest that Morpeth and Fedora 17 differ in morpho-physiological adaptations for optimum photosynthesis and growth, with high leaf chlorophyll and coarse root length achieved by Morpeth and high intercellular CO2 concentration and shoot length by Fedora 17. Conclusions: Morpeth and Fedora 17 had high shoot biomass, root length, root surface area and agronomic P-use and P-utilisation efficiencies in response to increasing soil P, while Han FNQ had moderate shoot yield, root growth, high citrate exudation, tissue P concentration and P-uptake efficiency. [ABSTRACT FROM AUTHOR]

In Arabidopsis thaliana, stomata are composed of two guard cells that control the aperture of a central pore to facilitate gas exchange between the plant and its environment, which is particularly important during photosynthesis. Although leaves are the primary photosynthetic organs of flowering plants, floral organs are also photosynthetically active. In the Brassicaceae, evidence suggests that silique photosynthesis is important for optimal seed oil content. A group of transcription factors containing MADS DNA binding domains is necessary and sufficient to confer floral organ identity. Elegant models, such as the ABCE model of flower development and the floral quartet model, have been instrumental in describing the molecular mechanisms by which these floral organ identity proteins govern flower development. However, we lack a complete understanding of how the floral organ identity genes interact with the underlying leaf development program. Here, we show that the MADS domain transcription factor AGAMOUS (AG) represses stomatal development on the gynoecial valves, so that maturation of stomatal complexes coincides with fertilization. We present evidence that this regulation by AG is mediated by direct transcriptional repression of a master regulator of the stomatal lineage, MUTE, and show data that suggests this interaction is conserved among several members of the Brassicaceae. This work extends our understanding of the mechanisms underlying floral organ formation and provides a framework to decipher the mechanisms that control floral organ photosynthesis. Author summary: Photosynthesis supports the growth and development of plants and is mainly associated with leaves. However, other organs, including floral organs, are photosynthetic and contribute to the energy requirements of the plant, which has attracted the interest of crop breeders. Despite its importance, very little is known about the establishment and molecular regulation of floral organ photosynthesis. Here, we describe the developmental progression and regulation of stomatal formation on the female reproductive organs of Arabidopsis thaliana before and after fertilization. Stomata control gas exchange between the plant and the environment, which facilitates photosynthesis and transpiration. We show that stomatal formation coincides with fertilization of the flower but does not depend upon it. Instead, the activity of a master regulator of stomatal development is directly controlled by a flower-specific factor. We present evidence that this regulation is conserved in several members of the mustard plant family (Brassicaceae) and suggest that the timing of stomatal formation on the female reproductive organs may be modified between species, which may have adaptive benefits. Given that floral organs are derived from leaves, this work also broadens and deepens our understanding of how the underlying leaf developmental program is rewired during flower development. [ABSTRACT FROM AUTHOR]

• Chromium (Cr) at 20 mg kg−1 displayed encouraging effects on the physiology of Mentha arvensis. • Cr at 80 mg kg−1 showed deleterious effects on plants. • Excessive Cr accumulation destabilizes plant's growth, photosynthesis and physiological markers. • Cr at higher concentration diminishes the essential oil production including menthol content. Chromium (Cr) is the seventh most toxic heavy metal on the earth's crust. Crop growth, development, and yield are greatly hindered by the massive accumulation of Cr that discharges from various industries and mines in agricultural land. Chromium can mediate phytotoxicity either via direct interaction with multiple plant components and metabolic pathways or by promoting reactive oxygen species (ROS) generation. Thus, this investigation evaluated the effect of Cr on growth, physiological and oxidative stress, and other parameters, including essential oil (EO) constituents of Mentha arvensis L. plants. The soil was treated with various concentrations of Cr (10, 20, 40, 60, and 80 mg kg−1), except the control. In this study, 20 mg kg−1 of Cr concentration was beneficial in increasing plant growth via the enhancement of biomass, photosynthesis, biochemical markers and EO constituents in M. arvensis. The data demonstrated that the morphological and physiological parameters were negatively correlated with high Cr concentrations (above 20 mg kg−1). It has been hypothesized that Cr poisoning leads to oxidative damage, as evidenced by decreases in photosynthetic rate, chlorophyll, and stomatal characteristics, as well as increases in lipid peroxidation and ROS. The accumulation of Cr positively correlates with the enhancement of proline and antioxidant activities of M. arvensis. Thus, we concluded that excess Cr causes redox imbalance by uplifting the level of lipid peroxidation and ROS by destabilizing photosynthetic machinery and other physiological and morphological markers in plants. [ABSTRACT FROM AUTHOR]

Stomata are the structures responsible for gas exchange in plants. The established framework for stomatal development is based on the model plant Arabidopsis, but diverse patterns of stomatal development have been observed in other plant lineages and species. The molecular mechanisms behind these diversified patterns are still poorly understood. We recently proposed a model for the molecular mechanisms of the diversification of stomatal development based on the genus Callitriche (Plantaginaceae), according to which a temporal shift in the expression of key stomatal transcription factors SPEECHLESS and MUTE leads to changes in the behavior of meristemoids (stomatal precursor cells). In the present study, we genetically manipulated Arabidopsis to test this model. By altering the timing of MUTE expression, we successfully generated Arabidopsis plants with early differentiation or prolonged divisions of meristemoids, as predicted by the model. The epidermal morphology of the generated lines resembled that of species with prolonged or no meristemoid divisions. Thus, the evolutionary process can be reproduced by varying the SPEECHLESS to MUTE transition. We also observed unexpected phenotypes, which indicated the participation of additional factors in the evolution of the patterns observed in nature. This study provides novel experimental insights into the diversification of meristemoid behaviors. [ABSTRACT FROM AUTHOR]

Background: Si can be important for the growth, functioning, and stoichiometric regulation of nutrients for high-Si-accumulating bamboo. However, other trees do not actively take up dissolved silicic acid [Si(OH)4] from the soil, likely because they have fewer or no specific Si transporters in their roots. It is unclear what causes differential growth and C:N:P stoichiometry between bamboo and other trees across levels of Si supply. Results: Si supply increased the relative growth rate of height and basal diameter of bamboo saplings, likely by increasing its net photosynthetic rate and ratios of N:P. Moreover, a high concentration of Si supply decreased the ratio of C:Si in bamboo leaves due to a partial substitution of C with Si in organic compounds. We also found that there was a positive correlation between leaf Si concentration and its transpiration rate in tree saplings. Conclusions: We demonstrated that Si supply can decrease the ratio of C:Si in bamboo leaves and increase the ratio of N:P without altering nutrient status or the N:P ratio of tree saplings. Our findings provide experimental data to assess the different responses between bamboo and other trees in terms of growth, photosynthesis, and C:N:P stoichiometry. These results have implications for assessing the growth and competition between high-Si-accumulating bamboo and other plants when Si availability is altered in ecosystems during bamboo expansion. Highlights: (1) Silicon (Si) supply improved the relative growth rate of height and basal diameter of bamboo saplings, which was in contrast to our findings for other tree saplings. (2) Si supply altered the photosynthetic gas exchange properties of plants, which in turn altered Si absorption from soil via passively uptake controlled by leaf transpiration. (3) The ratio of C:Si for all tissues in bamboo was much lower than other tree saplings. Specifically, Si supply decreased the ratio of C:Si in bamboo leaves due to a partial substitution of organic C compounds by Si. [ABSTRACT FROM AUTHOR]

Crassulacean acid metabolism (CAM) is a photosynthetic adaptation found in at least 38 plant families. Typically, the anatomy of CAM plants is characterized by large photosynthetic cells and a low percentage of leaf volume consisting of internal air space (% IAS). It has been suggested that reduced mesophyll conductance (g m) arising from low % IAS benefits CAM plants by preventing the movement of CO2 out of cells and ultimately minimizing leakage of CO2 from leaves into the atmosphere during day-time decarboxylation. Here, we propose that low % IAS does not provide any adaptive benefit to CAM plants, because stomatal closure during phase III of CAM will result in internal concentrations of CO2 becoming saturated, meaning low g m will not have any meaningful impact on the flux of gases within leaves. We suggest that low % IAS is more likely an indirect consequence of maximizing the cellular volume within a leaf, to provide space for the overnight storage of malic acid during the CAM cycle. [ABSTRACT FROM AUTHOR]

The effects of sulfate on the zinc (Zn) bioaccumulation characteristics and photophysiological mechanisms of the ornamental plant Hydrocotyle vulgaris were explored using a hydroponic culture under three Zn concentrations (300, 500 and 700 mg L−1) with (400 μmol L−1) or without the addition of sulfate. Results showed that: (1) tissue Zn concentrations and total Zn contents increased with increasing hydroponic culture Zn concentrations; and sulfate addition decreased Zn uptake and translocation from roots to shoots; (2) Zn exposure decreased photosynthetic pigment synthesis, while sulfate changed this phenomenon, especially for chlorophyll a under 300 mg L−1 Zn treatment; (3) Zn exposure decreased photosynthetic function, while sulfate had positive effects, especially on the photosynthetic rate (Pn) and stomatal conductance (Gs); and (4) chlorophyll fluorescence parameters related to light energy capture, transfer and assimilation were generally downregulated under Zn stress, while sulfate had a positive effect on these processes. Furthermore, compared to photosynthetic pigment synthesis and photosynthesis, chlorophyll fluorescence was more responsive, especially under 300 mg L−1 Zn treatment with sulfate addition. In general, Zn stress affected photophysiological processes at different levels, while sulfate decreased Zn uptake, translocation, and bioaccumulation and showed a positive function in alleviating Zn stress, ultimately resulting in plant growth promotion. All of these results provide a theoretical reference for combining H. vulgaris with sulfate application in the bioremediation of Zn-contaminated environments at the photophysiological level. Excessive zinc reduces the photosynthetic levels of plants. In this study, we investigated how damage caused by Zn stress may be alleviated. We found that exogenous sulfate could improve the photosynthetic levels of the ornamental plant Hydrocotyle vulgaris under Zn stressed. The results of this study provide a reference for the restoration of Zn-contaminated environments by the combining of H. vulgaris with sulfate at the photophysiological level. [ABSTRACT FROM AUTHOR]