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New techniques and approaches have been developed for root phenotyping recently; however, rapid and repeatable non-invasive root phenotyping remains challenging. Here, we present GrowScreen-PaGe, a non-invasive, highthroughput phenotyping system (4 plants min-1) based on flat germination paper. GrowScreen-PaGe allows the acquisition of time series of the developing root systems of 500 plants, thereby enabling to quantify short-term variations in root system. The choice of germination paper was found to be crucial and paper root interaction should be considered when comparing data from different studies on germination paper. The system is suitable for phenotyping dicot and monocot plant species. The potential of the system for high-throughput phenotyping was shown by investigating phenotypic diversity of root traits in a collection of 180 rapeseed accessions and of 52 barley genotypes grown under control and nutrient-starved conditions. Most traits showed a large variation linked to both genotype and treatment. In general, root length traits contributed more than shape and branching related traits in separating the genotypes. Overall, results showed that GrowScreen-PaGe will be a powerful resource to investigate root systems and root plasticity of large sets of plants and to explore the molecular and genetic root traits of various species including for crop improvement programs. [ABSTRACT FROM AUTHOR]

Over the past 50 years, the understanding of meiosis has aged like a fine bottle of wine: the complexity is developing but the wine itself is still young. While emphasis in the plant kingdom has been placed on the model diploids Arabidopsis(Arabidopsis thalianaL.) and rice (Orzya sativaL.), our research has mainly focussed on the polyploid, bread wheat (Triticum aestivumL.). Bread wheat is an important food source for nearly two-thirds of the world's population. While creating new varieties can be achieved using existing or advanced breeding lines, we would also like to introduce beneficial traits from wild related species. However, expanding the use of non-adapted and wild germplasm in cereal breeding programs will depend on the ability to manipulate the cellular process of meiosis. Three important and tightly-regulated events that occur during early meiosis are chromosome pairing, synapsis and recombination. Which key genes control these events in meiosis (and how they do so) remains to be completely answered, particularly in crops such as wheat. Although the majority of published findings are from model organisms including yeast (Saccharomyces cerevisiae) and the nematode Caenorhabditis elegans, information from the plant kingdom has continued to grow in the past decade at a steady rate. It is with this new knowledge that we ask how meiosis will contribute to the future of cereal breeding. Indeed, how has it already shaped cereal breeding as we know it today? [ABSTRACT FROM AUTHOR]

The outcome of infection of individual plants by pathogenic organisms is governed by complex interactions between the host and pathogen. These interactions are the result of long-term co-evolutionary processes involving selection and counterselection between plants and their pathogens. These processes are ongoing, and occur at many spatio-temporal scales, including genes and gene products, cellular interactions within host individuals, and the dynamics of host and pathogen populations. However, there are few systems in which host–pathogen interactions have been studied across these broad scales. In this review, we focus on research to elucidate the structure and function of plant resistance and pathogen virulence genes in the flax-flax rust interaction, and also highlight complementary co-evolutionary studies of a related wild plant–pathogen interaction. The confluence of these approaches is beginning to shed new light on host–pathogen molecular co-evolution in natural environments. [ABSTRACT FROM AUTHOR]

Root nodules are formed as a result of an orchestrated exchange of chemical signals between symbiotic nitrogen fixing bacteria and certain plants. In plants that form nodules in symbiosis with actinorhizal bacteria, nodules are derived from lateral roots. In most legumes, nodules are formed de novofrom pericycle and cortical cells that are re-stimulated for division and differentiation by rhizobia. The ability of plants to nodulate has only evolved recently and it has, therefore, been suggested that nodule development is likely to have co-opted existing mechanisms for development and differentiation from lateral root formation. Auxin is an important regulator of cell division and differentiation, and changes in auxin accumulation and transport are essential for lateral root development. There is growing evidence that rhizobia alter the root auxin balance as a prerequisite for nodule formation, and that nodule numbers are regulated by shoot-to-root auxin transport. Whereas auxin requirements appear to be similar for lateral root and nodule primordium activation and organ differentiation, the major difference between the two developmental programs lies in the specification of founder cells. It is suggested that differing ratios of auxin and cytokinin are likely to specify the precursors of the different root organs. [ABSTRACT FROM AUTHOR]

Higher plants comprise mixtures of some 40 different cell types, and this often complicates the interpretation of data obtained at the tissue level. Studies for a given cell type may provide novel insights into the mechanisms underlying defined cellular and developmental processes. In this regard, the cotton fibre represents an excellent single-cell model to study the control of rapid cell elongation and cellulose synthesis. These single cells, initiated from the ovule epidermis at anthesis, typically elongate to ~3?5cm in the tetraploid species before they switch to intensive secondary cell wall cellulose synthesis. By maturity, more than 94% of fibre weight is cellulose. To unravel the mechanisms of fibre elongation and cellulose synthesis, two hypotheses have been examined: (a) that sucrose degradation and utilisation mediated by sucrose synthase (Sus) may play roles in fibre development and (b) that symplastic isolation of the fibre cells may be required for their rapid elongation. Reverse genetic and biochemical analyses have revealed the critical role that Sus plays in fibre initiation and early elongation. Late in development, plasma-membrane and cell wall association of Sus protein seems to be involved in rapid cellulose synthesis. Cell biology and gene expression studies showed a temporary closure of fibre plasmodesmata (PD), probably due to the deposition of callose, at the rapid phase of elongation. The duration of the PD closure correlates positively with the final fibre length attained. These data support the view that PD closure may be required for fibres to achieve extended elongation. The branching of PD towards the secondary cell wall stage is postulated to function as a molecule sieve for tight control of macromolecule trafficking into fibres to sustain intensive cellulose synthesis. [ABSTRACT FROM AUTHOR]

Eucalyptus grandis Hill ex Maiden and its hybrids are commonly planted by the Brazilian pulp and paper industry, but they are the most susceptible to the neotropical rust disease caused by Puccinia psidii Winter. In an initial attempt to understand the mechanisms of resistance, we constructed two contrasting Serial Analysis of Gene Expression (SAGE) libraries using susceptible and resistant individuals from a segregating half-sibling E. grandis population. Using the Z-test we identified tags differentially expressed between the libraries, preferentially 239 in the susceptible and 232 in the resistant type individuals. Using public (Expressed Sequence Tags) EST databases, 40 of the susceptible and 70 of the resistant tags matched ESTs and were annotated. By comparing the type of genes and their expression levels, distinct differences between the libraries were observed. Susceptible plants showed gene expression linked to leaf senescence, generalised stress responses and detoxification, and are apparently incapable of inducing a competent host defence response. On the other hand, resistant plants showed genes upregulated for cellular polarisation, cytoskeleton restructuring, vesicle transport, and cellulose and lignin biosynthesis. In the resistant individuals, evidence for systemic resistance, anti-oxidative responses and a hypersensitive response was also observed, although no R gene was identified. [ABSTRACT FROM AUTHOR]

Dissemination of new knowledge is arguably the most critical component of the academic activity. In this context, scientific publishing is a pinnacle of any research work. Although the scientific content has always been the primary measure of a paper's impact, by itself it may not always be sufficient for maximum impact. Good scientific writing and ability to meet priority characteristics of the target journal are essential, and inability to meet appropriate standards may jeopardise the chances for dissemination of results. This paper analyses the key features necessary for successfully publishing scientific research manuscripts. Conclusions are validated by a survey of 22 international scientific journals in agriculture and plant biology whose editors-in-chief have provided current data on key features related to manuscript acceptance or rejection. The top priorities for manuscript rejection by scientific journals in agriculture and plant biology are: (1) lack of sufficient novelty; (2) flaws in methods or data interpretation; (3) inadequate data analyses; and (4) poor critical scientific thinking. The inability to meet these requirements may result in rejection of even the best set of data. Recommendations are made for critical thinking and integration of good scientific writing with quality research. These recommendations will improve the quality of manuscripts submitted for publication to scientific journals and hence improve their likelihood of acceptance. This paper analyses key features necessary for successfully publishing scientific manuscripts based on a review of characteristics for scientific writing and a survey of 22 international journals in agriculture and plant sciences. Top reasons for manuscript rejection are: (1) lack of novelty, (2) flaws in methodology or data interpretation; (3) inadequate data analyses; and (4) poor critical scientific thinking. Recommendations here will improve the quality of manuscripts submitted for publication to scientific journals and hence improve the rate of publication success. [ABSTRACT FROM AUTHOR]

Water stress (drought and waterlogging) leads to an imbalance in plant water distribution, disrupts cell homeostasis, and severely inhibits plant growth. Melatonin is a growth hormone that plants synthesise and has been shown to resist adversity in many plants. This review discusses the biosynthesis and metabolism of melatonin, as well as the changes in plant morphology and physiological mechanisms caused by the molecular defence process. Melatonin induces the expression of related genes in the process of plant photosynthesis under stress and protects the structural integrity of chloroplasts. Exogenous melatonin can maintain the dynamic balance of root ion exchange under waterlogging stress. Melatonin can repair mitochondria and alleviate damage caused by reactive oxygen species and reactive nitrogen species; and has a wide range of uses in the regulation of stress-specific genes and the activation of antioxidant enzyme genes. Melatonin improves the stability of membrane lipids in plant cells and maintains osmotic balance by regulating water channels. There is crosstalk between melatonin and other hormones, which jointly improve the ability of the root system to absorb water and breathe and promote plant growth. Briefly, as a multifunctional molecule, melatonin improves the tolerance of plants under water stress and promotes plant growth and development. Melatonin, as an exogenous hormone, has been widely used in improving plant stress resistance. This paper systematically describes how melatonin improves the ability of plants to resist water stress (drought and waterlogging) in the processes of photosynthesis, antioxidation and osmosis at the physiological and genetic levels. Melatonin can also improve plant stress resistance with other hormone crosstalk, which has high application value. [ABSTRACT FROM AUTHOR]

Agricultural soils contaminated with heavy metals (HMs) impose a threat to the environmental and to human health. Amendment with biochar could be an eco-friendly and cost-effective option to decrease HMs in contaminated soil. This paper reviews the application of biochar as a soil amendment to immobilise HMs in contaminated soil. We discuss the technologies of its preparation, their specific properties, and effect on the bioavailability of HMs. Biochar stabilises HMs in contaminated soil, enhance the overall quality of the contaminated soil, and significantly reduce HM uptake by plants, making it an option in soil remediation for HM contamination. Biochar enhances the physical (e.g. bulk density, soil structure, water holding capacity), chemical (e.g. cation exchange capacity, pH, nutrient availability, ion exchange, complexes), and biological properties (e.g. microbial abundance, enzymatic activities) of contaminated soil. Biochar also enhances soil fertility, improves plant growth, and reduces the plant availability of HMs. Various field studies have shown that biochar application reduces the bioavailability of HMs from contaminated soil while increasing crop yield. The review highlights the positive effects of biochar by reducing HM bioavailability in contaminated soils. Future work is recommended to ensure that biochars offer a safe and sustainable solution to remediate soils contaminated with HMs. [ABSTRACT FROM AUTHOR]

The fatty acyl-acyl carrier protein thioesterase B (FATB) gene, involved in the synthesis of saturated fatty acids, plays an important role in the content of fatty acid and composition of seed storage lipids. However, the role of FATB in soybeans (Glycine max) has been poorly characterised. This paper presents a preliminary bioinformatics and molecular biological investigation of 10 hypothetical FATB members. The results revealed that GmFATB1B, GmFATB2A and GmFATB2B contain many response elements involved in defense and stress responses and meristem tissue expression. Moreover, the coding sequences of GmFATB1A and GmFATB1B were significantly longer than those of the other genes. Their expression varied in different organs of soybean plants during growth, with GmFATB2A and GmFATB2B showing higher relative expression. In addition, subcellular localisation analysis revealed that they were mainly present in chloroplasts. Overexpression of GmFATB1A, GmFATB1B, GmFATB2A and GmFATB2B in transgenic Arabidopsis thaliana plants increased the seed oil content by 10.3%, 12.5%, 7.5% and 8.4%, respectively, compared to that in the wild-type and led to significant increases in palmitic and stearic acid content. Thus, this research has increased our understanding of the FATB family in soybeans and provides a theoretical basis for subsequent improvements in soybean quality. [ABSTRACT FROM AUTHOR]

The co-occurrence of salinisation and alkalisation is quite frequent in problematic soils and poses an immediate threat to food, feed and nutritional security. In the present study, root system architectural traits (RSAs) and ion profiling were evaluated in 21 genotypes of Avena species to understand the effect of salinity-alkalinity stress. The oat genotypes were grown on germination paper and 5-day-old seedlings were transferred to a hydroponic system for up to 30 days. These seedlingswere subjected to seven treatments: T0, treatment control (Hoagland solution); T1, moderate salinity (50 mM); T2, high salinity (100 mM); T3, moderate alkalinity (15 mM); T4, high alkalinity (30 mM); T5, combined moderate salinity-alkalinity (50 mM + 15 mM); and T6, combined high salinity-alkalinity (100 mM and 30 mM) by using NaCl + Na2SO4 (saline) and NaHCO3 + Na2CO3 (alkaline) salts equivalently. The root traits, such as total root area (TRA), total root length (TRL), total root diameter (TRD), total root volume (TRV), root tips (RT), root segments (RS), root fork (RF) and root biomass (RB) were found to be statistically significant (P < 0.01) among the different genotypes, treatments and their interactions. Na+ and K+ content analysis in root and shoot tissues revealed the ion homeostasis capacity of different Avena accessions under stress treatments. Principal component analysis (PCA) covered almost 83.0% of genetic variation and revealed that the sharing of TRA, RT, RS and RF traits was significantly high. Biplot analysis showed a highly significant correlation matrix (P < 0.01) between the pairs of RT and RS, TRL and RS, and RT and RF. Based on PCA ranking and relative value for stress tolerance, IG-20-1183, IG-20-894, IG-20-718 and IG-20-425 expressed tolerance to salinity (T2), IG-20-425 (alkalinity; T4) and IG-20-1183, IG-20-894 and IG-20-1004 were tolerant to salt-alkali treatment (T6). Multi-trait stability index (MTSI) analysis identified three stable oat genotypes (IG-20-714, IG-20-894 and IG-20-425) under multiple environments and these lines can be used in salinity-alkalinity affected areas after yield trials or as donor lines for combined stresses in future breeding programs. [ABSTRACT FROM AUTHOR]

Anthropogenic activities such as mining, fossil fuel combustion, fertilisers and pesticides utilisation in agriculture, metallurgic processes and disposal of industrial wastes have contributed an exponential rise in arsenic content in environment. The present paper deals with arsenate (AsV) incited stress in chickpea (Cicer arietinum L.) plants and its alleviation through the application of nitric oxide (NO) and spermidine (SPD). The exposure of C. arietinum to AsV reduced seedling length, biomass, relative water content and biochemical constituents. All the above-mentioned parameters were escalated when sodium nitroprusside (SNP) or SPD were utilised alone or in combination with AsV. The electrolyte leakage and malondialdehyde content were increased in chickpea treated with AsV, but reduced in combine treatment (As + SNP + SPD). In chickpea seedlings, 89.4, 248.4 and 333.3% stimulation were recorded in sugar, proline and glycine betaine contents, respectively, with As + SNP + SPD treatment in comparison to control. SNP and SPD modulated function of glyoxalase enzymes by which methylglyoxal (MG) was significantly detoxified in C. arietinum. Maximum reduction 45.2% was observed in MG content in SNP + SPD treatment over AsV stress. Hence, synergistic application of NO and SPD protected chickpea plants against AsV-generated stress by strengthening the antioxidant defence and glyoxalase system, which helped in regulation of biochemical pathways. Anthropogenic activities have contributed an exponential rise in arsenic content in environment. The present paper deals with arsenic (AsV) incited stress in chickpea (Cicer arietinum L.) plants and its alleviation through the application of nitric oxide and spermidine (SPD). We hypothesise that synergistic impact of sodium nitroprusside (SNP) and SPD may improve physiological and biochemical processes of chickpea to enhance its tolerance against arsenic toxicity. [ABSTRACT FROM AUTHOR]

Soil salinisation is a growing threat to global agriculture, reducing crop yields. Brassicaceae crops are vital vegetables and cash crops. Salt stress significantly affects the growth and development of Brassicaceae crops. A better understanding of the molecular and physiological mechanisms of salt tolerance is of theoretical and practical importance to improve Brassicaceae crop's salt tolerance and crop quality. Combined with previous research results, we discuss recent advances in research on salt stress response and salt tolerance in Brassicaceae crops. We summarised recent research progress on the physiological and molecular mechanisms of ionic homeostasis, antioxidant regulation, hormonal regulation and accumulation of osmotic-adjustment substances. We also discussed the molecular mechanism of Brassicaceae crop salt tolerant varieties from the perspective of differentially expressed genes, differentially expressed proteins and metabolites through transcriptome, proteome and metabonomic analysis methods. This paper summarises the molecular mechanisms in the perspective of differentially expressed genes, differentially expressed proteins, and metabolites through transcriptomic, proteome and metabolomics analysis. The review provides abundant data for accelerating the breeding of salt-tolerant Brassicaceae and laid a foundation for understanding the mechanism of salt tolerance of Brassicaceae crops and breeding salt-tolerance varieties. [ABSTRACT FROM AUTHOR]

This document is a corrigendum for an article titled "Understanding the role of the fructose-1,6-bisphosphatase gene for enhancing the photosynthetic rate in Arabidopsis thaliana" published in Functional Plant Biology. The corrigendum corrects the affiliations listed for author Mohammad Javed Ansari in the original paper. The correct affiliations are provided for all authors, including Fatima Gulzar, Raza Ahmad, Suk-Yoon Kwan, Zulqurnain Khan, Sulaiman Ali Alharbi, Mohmmad Maroof Shah, Shoaib ur Rehman, Maria Siddique, Mohammad Javed Ansari, Irum Shahzadi, Muhammad Abu Bakar Saddique, Muhmmad Zahid Ishaq, and Ummara Waheed. The affiliations are from various institutions in Pakistan, Republic of Korea, Saudi Arabia, and India. [Extracted from the article]

This document is a corrigendum for an article titled "Physiological and biochemical assortment in different wheat genotypes (Triticum aestivum L.) under rain fed conditions" published in Functional Plant Biology. The corrigendum states that the authors failed to acknowledge funding in the original paper and provides the correct acknowledgement. The authors express their appreciation to the Researchers Supporting Project Number (RSP2023R369), King Saud University, Riyadh, Saudi Arabia. The corrigendum provides the corrected information and is published by CSIRO Publishing. [Extracted from the article]

Current research focused on the potential role of zinc oxide nanoparticles (ZnONPs) and potassium (K+) in mitigation of arsenic (As) toxicity in Vicia faba L. seedlings. Faba bean seedlings were grown for 30 days in potted soil. As stress curtailed root and shoot length, chlorophyll (Chl) content and net photosynthetic rate in V. faba seedlings. However, ZnONPs and K+ curtailed As stress in faba bean seedling through enhanced activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) enzyme. Furthermore, ZnONPs and K+ significantly enhanced cysteine (Cys) content and serine acetyletransferase (SAT) activity in faba bean seedling exposed to As-toxificated soil. Application of ZnONPs and K+ curtailed superoxide ionic content and hydrogen peroxide (H2O2) accumulation in V. faba seedlings exposed to As-polluted soil. Nitric oxide (NO) content also increased in faba bean seedlings treated with ZnONPs and K+ in normal and As-polluted soil. As stress alleviation was credited to reduce As uptake in faba bean seedlings treated with synergistic application of ZnONPs and K+. It is proposed that K+ interaction with nanoparticles can be exploited at molecular level to understand the mechanisms involved in abiotic stress tolerance. Recently, Industrialisation and modern approaches have increased the level of arsenic in our environment. Higher concentration of arsenic has reduced growth of plants. This paper focuses on the role of nanoparticles in reduction of toxic effects of heavy metals. Results clearly state that nanoparticles can be used in combination with potassium silicate to enhance crop production. [ABSTRACT FROM AUTHOR]

Underwater germination could risk seedling survival, suggesting the need for control through seed perception of environmental cues. These cues include diurnally alternating temperatures tied to drained soils or shallow water tables. We examined high-amplitude alternating temperatures impact on underwater germination. Besides, the conditions experimented by seeds in the soil (e.g. hydration/dehydration phases) change their germinability so we tested if osmopriming could affect underwater germination. We worked with Echinochloa colona seedlots from extensive crop fields, exposing seeds to sequential submergence and drained treatments in combination with cues that promote germination. While a 10℃ difference between maximumand minimumdaily temperatures maximised germination in drained conditions, higher amplitudes (>15℃) alternating temperatures promoted E. colona underwater germination under hypoxic water (pO2 < 4.1 kPa). KNO3 osmopriming in drained conditions promoted later underwater germination even under hypoxic water; however, PEG 6000 osmopriming induced seeds to enter secondary dormancy inhibiting underwater germination. KNO3 improved E. colona underwater germination under air-equilibrated floodwater (pO2: 16.5-17.4 kPa) yet not under hypoxic conditions. This suggests that germination can proceed in flooded nitrate-fertile soils as long as it remains aerobic. Hypoxic submergence did not inhibit the induction of hypersensitivity to light in E. colona seeds. This research expands our understanding of wetland seed germination ecophysiology, shedding light on the inducible nature of underwater germination in hydrophyte weeds. [ABSTRACT FROM AUTHOR]

Highland barley (Hordeum vulgare L.), as the dominant crop on the Qinghai-Tibetan Plateau, is a typical representative of plants adapted to extreme environmental conditions. However, the harsh environment, severe salinisation and frequent freezing and thawing in the Qinghai-Tibetan Plateau are main limiting factor for crop growth in this region. The physiological response of highland barley to salinisation and freeze–thaw stresses was studied in this paper. Under the combined stresses of 60 mmol/L NaCl·60 mmol/L NaHCO3 and freeze–thaw cycles (10, −5, and 10°C), the changes in the relative moisture content, relative electrical conductivity, soluble protein, malondialdehyde (MDA) and photosynthetic indices Pn and E in seedling leaves of eight groups of treatments (CK, S, A, S-A, CK (FT), S (FT), A (FT), and S-A (FT)) were analysed. Results showed that a single stress did not cause a change in the MDA content. All of the combined stresses in S-A, CK (FT), S (FT), A (FT), and S-A (FT) treatments increased the MDA content of barley seedlings, and the MDA content of S-A (FT) reached 28.438 at T2 (−5°C) μmol/g. During the freeze–thaw cycle, the cell membrane of seedlings was damaged more seriously by alkali stress, which showed a significant increase in relative conductivity. The relative moisture content value of seedlings was more than 100% because the seedlings could absorb more moisture due to mechanical injury. The protein content of osmoregulatory substances in highland barley seedlings increased with increasing stress, indicating resistance to stress. Moreover, the effect of freeze–thaw stress on photosynthesis was more significant. The changes in indices proved that an appropriate amount of salt stress could improve the resistance of the plant cell membrane. Alkali stress had a significant effect on the growth of highland barley seedlings. Freezing and thawing can aggravate the damage of saline–alkali stress to highland barley seedlings, resulting in changes in the biological membrane permeability and photosynthesis of seedlings. The fluctuation of osmoregulation substance content confirmed that highland barley seedlings had a certain degree of stress resistance. Freeze–thaw cycles will aggravate the damage of land salinisation to highland barley seedlings. To better reduce the impact and loss of land salinisation and freeze–thaw disasters on agriculture in the Qinghai-Tibetan Plateau, priority should be given to solving freeze–thaw stress in the process of grain production. Highland barley (Hordeum vulgare L.) is one of the important food crops for Tibetans. However, the environment in the Qinghai-Tibet Plateau is challenging for plant growth with combined stresses of saline–alkali and freeze–thaw affecting grain yield and quality. Research shows that the freeze–thaw cycle aggravate the damage of saline–alkali stress to highland barley seedlings, affecting biofilm permeability, osmotic adjustment and seedling photosynthesis. The results of this study will provide guidance and suggestions for improving crop production. [ABSTRACT FROM AUTHOR]

Tolerance to freezing and seedling diseases caused by Microdochium spp. is an essential trait for the wintering of triticale (×Triticosecale Wittmack) and other cereals. Preceding multi-year studies indicate that after long-term exposure to the low temperature, cereal seedlings acquire a genotype-dependent cross-tolerance to other subsequent stresses. This paper presents the first non-gel protein profiling performed via high performance liquid chromatography coupled with Mass Spectrometry as well as Fourier Transform-Raman spectroscopy measurements performed directly on leaves of triticale seedlings growing under different conditions. The research used doubled haploid lines selected from the mapping population, with extreme tolerance/susceptibility to freezing and M. nivale infection. These non-targeted methods led to the detection of twenty two proteins cold-accumulated in the most tolerant seedlings in relation to susceptible ones, classified as involved in protein biosynthesis, response to different stimuli, energy balancing, oxidative stress response, protein modification, membrane structure and anthocyanin synthesis. Additionally, in seedlings of the most freezing- and M. nivale-tolerant line, cold-hardening caused decrease of the carotenoid and chlorophyll content. Moreover, a decrease in the band intensity typical for carbohydrates as well as an increase in the band intensity characteristic for protein compounds were detected. Both studied lines revealed a different answer to stress in the characteristics of phenolic components. [ABSTRACT FROM AUTHOR]

In Tunisia, drought stress is a major environmental factor limiting crop production and causing relatively low and unstable faba bean yields. In the present study, we explored the putative role of spermidine (0.5, 1, 1.5 and 2 mM) in ameliorating the effects of drought stress induced by polyethylene glycol (PEG-6000, -0.58 MPa) in faba bean seedlings. Drought stress reduced photosynthetic performance, chlorophyll and relative water content in leaves of faba bean variety Badii. Moreover, drought increased proline, electrolyte leakage and malondialdehyde content by inducing reactive oxygen species (hydrogen peroxide) generation in leaves. However, applying spermidine increased the activities of catalase, superoxide dismutase, ascorbate peroxidase and guaiacol peroxidase. The results show that the application of spermidine especially at a rate of 1.5 mM effectively reduces oxidative damage and alleviates negative effects caused by drought stress. In addition, exogenous spermidine increased the expression of polyamine biosynthetic enzymes' genes (VfADC, VfSAMDC and VfSPDS), and reduced the expression of VfSPMS suggesting that exogenous spermidine can regulate polyamines' metabolic status under drought challenge, and consequently may enhance drought stress tolerance in faba bean. Real-time quantitative polymerase chain reaction analysis revealed that some drought responsive genes (VfNAC, VfHSP, VfNCED, VfLEA, VfCAT, VfAPX, VfRD22, VfMYB, VfDHN, VfERF, VfSOD and VfWRKY) from various metabolic pathways were differentially expressed under drought stress. Overall, these genes were more abundantly transcribed in the spermidinetreated plants compared to untreated suggesting an important role of spermidine in modulating faba bean drought stress response and tolerance. [ABSTRACT FROM AUTHOR]

An antisense oligonucleotide (ASO) is a short single-stranded deoxyribonucleotide complementary to the sense strand of a selected nucleic acid. As a result, an ASO can modulate gene expression through several mechanisms. The technology based on ASO has already been applied in studies on gene function in mammalian cells and selective therapeutic strategies for many diseases. The conceptual simplicity and low cost of this method, and the developments in the field of plant genome sequencing observed in the last decades, have paved the way for the ASO method also in plant biology. It is applied in gene function analysis as well as the development of non-invasive plant production technology involving gene modifications without transgenesis. Therefore, the first part of this review provides a comprehensive overview of the structure, mechanism of action and delivery methods of ASOs in plants and shows the most important features essential for the proper design of individual experiments. We also discuss potential issues and difficulties that may arise during practical ASO implementation. The second part of this article contains an analysis of ASO applications in various studies in the field of plant biology. We presented for the first time that ASOs were also successfully applied in cucumber. This paper reviews important features implementing experiments using antisense oligonucleotide (ASO) technology in plants. Strong social non-acceptance of GMO creates demand for the development of the alternative technologies not connected with introducing of foreign genes into the plant genome. ASO technology seems to be one of the solution that meets these demands. Many successful applications of ASO in different plant species have already been reported. For the first time, we present ASOs successfully applied in Cucumis sativus L. (cucumber). [ABSTRACT FROM AUTHOR]

To investigate the function of melatonin (MT) on nitrogen uptake and metabolism in soybean, six groups of treatments, with and without 100 µM melatonin were conducted at low, normal, and high nitrogen levels (1.5, 7.5, and 15 mM, respectively). The related indexes of nitrogen metabolism and the antioxidant system of seedlings were measured and analysed. Results indicated that MT could enhance the level of nitrogen metabolism by upregulating the coding genes of enzymes related to nitrogen metabolism and increasing total nitrogen content, especially under low nitrogen levels. Under high nitrogen conditions, the addition of MT not only accelerated ammonium assimilation and utilisation by enhancing the activity of glutamine synthetase involved in ammonium assimilation, but also reduced the extent of membrane lipid peroxidation to alleviate the degree of damage by improving the activity of antioxidant enzymes. In addition, MT enhanced soybean growth with positive effects in morphological changes at different nitrogen levels, including significantly increased stem diameter, total leaf area, and root nodule number, and biomass accumulation. Finally, biomass accumulation increased under low, normal, and high nitrogen levels by 9.80%, 14.06%, and 11.44%, respectively. The results suggested that MT could enhance the soybean tolerance to low and excessive N treatments. [ABSTRACT FROM AUTHOR]

The distributions of CAM and C3 epiphytic bromeliads across an altitudinal gradient in western Panama were identified from carbon isotope (δ13C) signals, and epiphyte water balance was investigated via oxygen isotopes (δ18O) across wet and dry seasons. There were significant seasonal differences in leaf water (δ18Olw), precipitation, stored 'tank' water and water vapour. Values of δ18Olw were evaporatively enriched at low altitude in the dry season for the C3 epiphytes, associated with low relative humidity (RH) during the day. Crassulacean acid metabolism (CAM) δ18Olw values were relatively depleted, consistent with water vapour uptake during gas exchange under high RH at night. At high altitude, cloudforest locations, C3 δ18Olw also reflected water vapour uptake by day. A mesocosm experiment with Tillandsia fasciculata (CAM) and Werauhia sanguinolenta (C3) was combined with simulations using a non-steady-state oxygen isotope leaf water model. For both C3 and CAM bromeliads, δ18Olw became progressively depleted under saturating water vapour by day and night, although evaporative enrichment was restored in the C3 W. sanguinolenta under low humidity by day. Source water in the overlapping leaf base 'tank' was also modified by evaporative δ18O exchanges. The results demonstrate how stable isotopes in leaf water provide insights for atmospheric water vapour exchanges for both C3 and CAM systems. The paper defines the niche segregation of C3 and CAM photosynthetic pathways for epiphytic bromeliads along an altitudinal gradient in Panama. Measurement of the leaf water oxygen (18O) stable isotope composition supports transpiration by day or night, since under high humidity water vapour influx resets the leaf water 18O signal. [ABSTRACT FROM AUTHOR]

Under increasing water scarcity, food production for an increasing population isaglobal challenge. Maintaining crop production under limiting water supply is a common problem in agriculture, which is best addressed by the coordinated efforts of geneticists, physiologists and agronomists. This special issue is a selection of oral and poster presentations at the InterDrought IV conference, held in Perth (2-6 September 2013). These papers provide a broad, multidisciplinary view on the way to develop improved cultivars in the face of water deficit, providing the conference highlight: an integration of views from different disciplinary angles, generating constructive debate that was not buried in disciplinary silos. More specifically, the topics covered deal with the challenge of adaptation implicit in genotype-by-environment interaction, bring new perspectives on root systems and water productivity, and review the challenges and opportunities provided by crop management, genomic and transgenic approaches to cultivar improvement. [ABSTRACT FROM AUTHOR]

Soil salinisation is a major abiotic stress in agriculture, and is especially a concern for rice production because among cereal crops, rice is the most salt-sensitive. However, the production of rice must be increased substantially by the year 2050 to meet the demand of the ever growing population. Hence, understanding the biochemical events determining salt tolerance in rice is highly desirable so that the trait can be introduced in cultivars of interest through biotechnological intervention. In this context, an initial study on NaCl response in four Indica rice varieties showed a lower uptake of Na+ in the salt-tolerant Nona Bokra and Pokkali than in the salt-sensitive IR64 and IR29, indicating Na+ exclusion as a primary requirement of salt tolerance in the species. This was also supported by the following features in the salt-tolerant, but not in the -sensitive varieties: (1) highly significant NaCl-induced increase in the activity of PM-H+ATPase, (2) a high constitutive level and NaCl-induced threonine phosphorylation of PM-H+ATPase, necessary to promote its activity, (3) a high constitutive expression of 14-3-3 protein that makes PM-H+ATPase active by binding with the phosphorylated threonine at the C -terminal end, (4) a high constitutive and NaCl-induced expression of SOS1 in roots, and (5) significant NaCl-induced expression of OsCIPK 24 , a SOS2 that phosphorylates SOS1. The vacuolar sequestration of Na+ in seedlings was not reflected from the expression pattern of NHX1/ NHX1 in response to NaCl. NaCl-induced downregulation of expression of HKTs in roots of Nona Bokra, but upregulation in Pokkali also indicates that their role in salt tolerance in rice could be cultivar specific. The study indicates that consideration of increasing exclusion of Na+ by enhancing the efficiency of SOS1/PM-H+ATPase Na+ exclusion module could be an important aspect in attempting to increase salt tolerance in the rice varieties or cultivars of interest. Rice is staple crop for the human population the world over, but its production is greatly affected by increasing salinisation of agricultural land. Hence, this paper focussed on understanding the salt tolerance determinants in the species, and exclusion of Na+ was found to be the primary mechanism governed by SOS1/PM-H+ATPase module. Therefore, attempts to increase salt tolerance in the rice cultivar of interest should target exclusion of Na+, primarily by manipulation of the efficiency of SOS1/PM-H+ATPase functioning. [ABSTRACT FROM AUTHOR]

Previous studies have suggested that the maintenance of redox homeostasis is essential for plant growth. Here we investigated how redox homeostasis and signalling is modulated in response to different nitrogen (N) forms in tea plant roots. Our results showed that both N deficiency and nitrate (NO3–) can trigger the production of hydrogen peroxide and lipid peroxidation in roots. In contrast, these responses were not altered by NH4+. Further, N deficiency and NO3–-triggered redox imbalance was re-established by increased of proanthocyanidins (PAs) and glutathione (GSH), as well as upregulation of representative antioxidant enzyme activities and genes. To further explore the molecular bases of these responses, comparative transcriptome analysis was performed, and redox homeostasis-associated differentially expressed genes (DEGs) were selected for bioinformatics analysis. Most of these genes were involved in the flavonoid biosynthesis, GSH metabolism and the antioxidant system, which was specifically altered by N deficiency or NO3–. Moreover, the interplay between H2O2 (generated by RBOH and Ndufab1) and hormones (including abscisic acid, auxin, cytokinin and ethylene) in response to different N forms was suggested. Collectively, the above findings contribute to an understanding of the underlying molecular mechanisms of redox homeostasis and signalling in alleviating oxidative stress in tea plant roots. Nitrogen availability has a major impact on tea productivity; however, how tea plants respond to different N forms remain unknown. Our findings reveal the molecular mechanisms of redox homeostasis and signalling in alleviating oxidative stress induced by N deficiency or NO3–. This paper provides candidate redox-related genes for researchers investigating abiotic stress in tea plants. [ABSTRACT FROM AUTHOR]

Plant breeders are in the need for a convenient, reproducible, reliable and rapid screening methods to be used as a proxy for drought tolerance for a large number of genotypes. Addressing this need, we compared different physiological measures of stress in six barley (Hordeum vulgare L.) genotypes subjected to different drought treatments under glasshouse conditions. Genotypes were evaluated by measuring transpiration rate, quantum yield of PSII (chlorophyll fluorescence Fv/Fm ratio), SPAD chlorophyll meter reading, dry biomass and shoot water content. The accuracy of different methods for quantifying water stress tolerance was evaluated by measuring the rates of surviving and death in plants and leaves, and newly grown leaves after rewatering. In another experiment, the same genotypes were evaluated by applying 18% (w/v) of polyethylene glycol (PEG) to germinating seeds grown in paper rolls to induce osmotic stress, using relative root and shoot lengths as a measure of tolerance. The results suggest that transpiration measurements at the recovery stage could be the most sensitive method for separating contrasting genotypes. However, the method is time-consuming and laborious for large-scale screening. Chlorophyll content, dry biomass, shoot water content and stomatal density did not correlate with plant drought tolerance. At the same time, chlorophyll fluorescence Fv/Fm ratio showed a strong correlation with drought tolerance and could be recommended as suitable proxy for screening. Measuring relative root growth rate (length) using PEG-treated paper roll-grown seedlings also seems to be a highly suitable and promising method for screening a large number of genotypes in breeding programs. [ABSTRACT FROM AUTHOR]

Leaf senescence is an important factor that affects crop yield traits and is regulated by various factors. Here, we propose the photo–carbon imbalance hypothesis to explain the mechanism of rice leaf senescence. The main idea of this hypothesis is that carbon assimilation decreases faster than the absorption of light energy in photosynthesis during the late stages of rice growth, which ultimately results in leaf senescence. Our results indicate that endogenous ascorbic acid (Asc) plays an important role in leaf senescence by affecting the expression of senescence genes, thereby influencing photosynthetic capacity and consequently grain yield. The effects of exogenous Asc and methyl jasmonate (MeJA) on photosynthetic capability implied that the balance between photoreaction and carbon assimilation is regulated by exogenous antioxidants or accelerators of senescence. The results of the shading treatments indicated that shading will mitigate the photo–carbon imbalance and improve photosynthetic capacity, resulting in increased yields. Increasing antioxidant concentrations can enhance the reactive oxygen species (ROS) scavenging capacity, whereas shading reduces excess light energy, which may help to restore the photo–carbon balance. The photo–carbon imbalance is an important hypothesis to explain the rice leaf senescence mechanism. In this paper we first verified the photo–carbon imbalance hypothesis to explain the mechanism of rice leaf senescence using transgenic rice plants, which have different endogenous ascorbic acid as materials. Our results show that shading treatment on rice plants results in increased yields significantly, which may be explained by the proposed photo–carbon imbalance hypothesis. [ABSTRACT FROM AUTHOR]

Stevia rebaudiana Bertoni has been promoted for having sweet leaves as well as pharmaceutical and industrial properties. The sweet taste of Stevia leaves is due to the presence of steviol glycosides (a group of diterpene glycosides) found in a small number of plants. In the biosynthetic pathway of steviol glycosides (SGs), 15 enzymes that express the genes are associated with these enzymes under the influence of the elicitors. Due to the individuality of the stevia and few studies on the biosynthesis pathway of SGs, this paper attempted to investigate the effects of some of the elicitors, including methyl jasmonate (MeJA), salicylic acid (SA), auxins (Aux), cytokinins (CKs), gibberellins (GAs) and its inhibitors including paclobutrazol (BPZ) and chloroquate (CCC)), on the responsible genes for the biosynthesis of SGs. Some of these elicitors, including MeJA, SA and GA have great potential in increasing secondary metabolites. Moreover, the biosynthetic pathway of GAs and SGs are shared till ent-kaurenoic acid (ent-KA) biosynthesis, which raises the question of whether this hormone and its inhibitors are effective in the SGs biosynthesis. Type 2 diabetes and obesity are two major risk factors for cardiovascular disease that are caused by over-consumption of sugar. Since artificial sweeteners have been shown to be harmful to health, natural extracts including steviol glycosides (SGs) are now considered the best substitute for sugar. We present new knowledge on the effect of elicitors on SGs biosynthesis, and show that an increase in plant yield can also increase these secondary metabolites. [ABSTRACT FROM AUTHOR]

Abscisic acid (ABA) regulates plant development, seed germination, and stress responses. The PYR1-like (PYL) proteins are essential for ABA signalling. However, the evolution and expression of PYL genes in potato (Solanum tuberosum) remain poorly understood. Here, we analysed and identified 17 PYL genes in the potato genome, which were categorised into three groups based on phylogenetic analysis. These genes are distributed across nine chromosomes with predicted proteins subcellar localisation primarily in the cytoplasm. These StPYLs revealed conserved exon structures and domains among the groups. Promoter region analysis indicated hormone and stress-related elements in all StPYL s. Protein–protein interactions and microRNA networks predicted that the interactions of StPYLs are crucial components of ABA signalling, underlining their pivotal role in stress management and growth regulation in potato. Expression profiling across different tissues and under various stresses revealed their varied expression pattern. Further, we validated the expression pattern of selected StPYLs through reverse transcription quantitative PCR under drought, salt, and Phytophthora infestans stresses. This revealed consistent upregulation of StPYL6 in these stresses, while StPYL11 exhibited significant downregulation over time. Other genes showed downregulation under drought and salt stresses while upregulation under P. infestans. Overall, our results suggested the potential role of PYL genes in abiotic and biotic stresses. Abscisic acid (ABA) is a key player in how plants adapt to their environment, from growth to coping with stress. In this study, we identified the PYL genes in potatoes (Solanum tuberosum), crucial for ABA signalling pathways, yet poorly understood in potato. We uncover 17 PYL genes in potatoes, revealing their diverse roles in stress response and growth regulation. These findings shed light on potential role of PYL genes in mitigating the multiple stresses. This article belongs to the Collection Functional Genomics for Developing Climate Resilient Crops. [ABSTRACT FROM AUTHOR]

One strategy to improve olive (Olea europaea) tree drought tolerance is through the symbiosis of arbuscular mycorrhizal fungi (AMF), which helps alleviate water deficit through a combination of morphophysiological effects. Cuttings of olive varieties Arbequina (A) and Barnea (B) were grown with (+AMF) or without (−AMF) inoculum in the olive grove rhizosphere soil. One year after establishment, pots were exposed to four different water regimes: (1) control (100% of crop evapotranspiration); (2) short-period drought (20 days); (3) long-period drought (25 days); and (4) rewatering (R). To evaluate the influence of AMF on tolerance to water stress, stem water potential, stomatal conductance and the biomarkers for water deficit malondialdehyde, proline, soluble sugars, phenols, and flavonoids were evaluated at the end of the irrigation regimes. Stem water potential showed higher values in A(+) and B(+) in all water conditions, and the opposite was true for stomatal conductance. For proline and soluble sugars, the stem water potential trend is repeated with some exceptions. AMF inoculum spore communities from A(+ and −) and B(+ and −) were characterised at the morphospecies level in terms of richness and abundance. Certain morphospecies were identified as potential drought indicators. These results highlight that the benefits of symbiotic relationships between olive and native AMF can help to mitigate the effects of abiotic stress in soils affected by drought. We evaluated different water regimes on young cuttings of olive (Olea europaea) cvs Arbequina and Barnea inoculated with or without arbuscular mycorrhizal fungi (AMF) in a central-western olive grove in Argentina. We measured AMF morphospecies richness and abundance in the soil, plant vegetative growth, plant adaptation to drought stress, and crop water status. We found that certain morphological, physiological and biochemicalindicators may be useful to identify new strategies to mitigate water stress and improve water use efficiency during transplantation. [ABSTRACT FROM AUTHOR]

Genetic transformation is helpful in enhancing crops, utilising promoters that can be constitutive, inducible, or tissue-specific. However, the use of constitutive promoters may hinder plant growth due to energy consumption during cellular processes. To optimise transgene effects, tissue-specific promoters like root-specific ones prove valuable in addressing root-related issues and enhancing productivity. Yet, identified root-specific promoters in crop are limited. To address this gap, the expression pattern of the root-specific SlREO promoter was examined across various crops. Sequencing confirmed its identity and high homology (99%) with the NCBI database, distinct from other plants tested. Using the PLACE database, six motifs associated with root expression were identified, along with several other important elements. The 2.4 kb SlREO promoter was linked to a ß-glucuronidase (GUS) reporter gene alongside the CaMV35S promoter in pRI 201-AN- GUS vectors to study its expression. Histochemistry revealed strong root-specific expression in tomato (Solanum lycopersicum) root tissues and limited expression in stems. However, the SlREO promoter did not consistently maintain its root-specific expression in other plants. Conversely, the CaMV35S promoter exhibited constitutive expression across all tissues in various plants. This study underscores the potential of the SlREO promoter as a root-specific regulatory element, offering avenues for improving crops, particularly against environmental stresses. The improvement of tomato (Solanum lycopersicum) for various biotic and abiotic traits that affect the roots functions is vital, and root-specific promoters are tools to improve the gene expression of transgenes. SlREO is one tissue-specific promoters in tomato. This study cloned and characterised SlREO in Indian tomato cultivar, and evaluated its activity in various crops. Transgenic studies suggest that SlREO is a crop-dependent tissue-specific promoter that cannot be used to improve the expression of genes in other crops. This article belongs to the Collection Functional Genomics for Developing Climate Resilient Crops. [ABSTRACT FROM AUTHOR]

This study reveals a new acclimation mechanism of the eukaryotic unicellular green alga Chlorella vulgaris in terms of the effect of varying atmospheric pressures on the structure and function of its photosynthetic apparatus using fluorescence induction measurements (JIP-test). The results indicate that low (400 mbar) and extreme low (<10 mbar) atmospheric pressure decreases the density and thus increases the fluidity of the thylakoid membrane, possibly facilitating plastoquinone (PQ) movement within the membrane and resulting in enhanced photosynthetic electron flow and photochemical quenching. Molecular dynamic simulations of different light harvesting complexes within thylakoid membrane models confirm this mechanism and reveal the associated atomic scale details. The exposure of microalga to an extremely low pressure (<10 mbar) in a 100% CO2 atmosphere (simulating the Mars atmosphere), reveals that the impact of extremely low atmospheric pressure on PQ mobility within the photosynthetic membrane, coupled with the low density of an almost 100% CO2 Mars-like atmosphere, results to a similar photosynthetic efficiency to that on Earth. These findings pave the way for the identification of novel functional acclimation mechanisms of microalgae to extreme environments that are vastly distinct from those found on Earth. This study reveals a new acclimation mechanism of microalgae in low atmospheric pressure. Experimental results and molecular dynamic simulations indicate that low atmospheric pressure reduces the density and enhances the fluidity of photosynthetic thylakoid membranes, leading to enhanced photochemical quenching. Particularly, extremely low pressure (<10 mbar) in a 100% CO2 atmosphere (Mars-like atmosphere) yields a photosynthetic efficiency comparable to that of Earth, shedding light on new astrobiological perspectives. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate whether silicon (Si) supply was able to alleviate the harmful effects caused by salinity stress on sorghum-sudangrass (Sorghum bicolor × Sorghum sudanense), a species of grass raised for forage and grain. Plants were grown in the presence or absence of 150 mM NaCl, supplemented or not with Si (0.5 mM Si). Biomass production, water and mineral status, photosynthetic pigment contents, and gas exchange parameters were investigated. Special focus was accorded to evaluating the PSI and PSII. Salinity stress significantly reduced plant growth and tissue hydration, and led to a significant decrease in all other studied parameters. Si supply enhanced whole plant biomass production by 50%, improved water status, decreased Na+ and Cl− accumulation, and even restored chlorophyll a , chlorophyll b , and carotenoid contents. Interestingly, both photosystem activities (PSI and PSII) were enhanced with Si addition. However, a more pronounced enhancement was noted in PSI compared with PSII, with a greater oxidation state upon Si supply. Our findings confirm that Si mitigated the adverse effects of salinity on sorghum-sudangrass throughout adverse approaches. Application of Si in sorghum appears to be an efficient key solution for managing salt-damaging effects on plants. Soil salinity is a worldwide environmental constraint that affects crops growth and productivity. Silicon supply has been observed to ameliorate crops growth under various stresses. In this study, silicon supply was found to significantly enhance the decline the growth of sorghum-sudangrass (Sorghum bicolor × Sorghum sudanense) under salinity stress, increasing productivity and enhancing plants vigour throughout many aspects. Hence, silicon seems to be a promising approach to strengthen agriculture yield. [ABSTRACT FROM AUTHOR]

Heliotropium thermophilum (Boraginaceae) plants have strong antioxidant properties. This study investigated the effectiveness of the antioxidant system in protecting the photosynthetic machinery of H. thermophilum. Plants were obtained from Kızıldere geothermal area in Buharkent district, Aydın, Turkey. Plants in the geothermal area that grew at 25–35°C were regarded as the low temperature group, while those that grew at 55–65°C were regarded as the high temperature group. We analysed the physiological changes of these plants at the two temperature conditions at stage pre-flowering and flowering. We meaured the effect of high soil temperature on water potential, malondialdehyde, cell membrane stability, and hydrogen peroxide analysis to determine stress levels on leaves and roots. Changes in antioxidant enzyme activities, ascorbate and chlorophyll content, chlorophyll fluorescence, photosynthetic gas exchange parameters, and photosynthetic enzymes (Rubisco and invertase) activities were also determined. Our results showed minimal changes to stress levels, indicating that plants were tolerant to high soil temperatures. In general, an increase in antioxidant enzyme activities, ascorbat levels, and all chlorophyll fluorescence parameters except for non-photochemical quenching (NPQ) and F v/ F m were observed. The pre-flowering and flowering stages were both characterised by decreased NPQ, despite F v/ F m not changing. Additionally, there was a rise in the levels of photosynthetic gas exchange parameters, Rubisco, and invertase activities. High temperature did not affect photosynthetic yield because H. thermophilum was found to stimulate antioxidant capacity, which reduces oxidative damage and maintains its photosynthetic machinery in high temperature conditions and therefore, it is tolerant to high soil temperature. Heliotropium thermophilum did not exhibit significant stress parameters under high soil temperature conditions, and it was a highly tolerant plant to high temperature. In the measurements taken at pre-flowering and flowering, plants in the pre-flowering stage were slightly more tolerant to high temperatures. The protection of PSII function in plants at higher temperatures could be linked to an increase in antioxidant activities. [ABSTRACT FROM AUTHOR]

Potassium (K) is essential for the development of grapevines (Vitis vinifera), accumulating into berries during maturation. Elevated K has been associated with high sugar and low acidity in juice. Characterising the accumulation patterns of K and other components in pericarps treated with various experimental factors may indicate potential regulators of berry K levels. A soil fertiliser trial using nutrient solutions with two K supply rates was conducted on potted Shiraz vines during berry ripening. Doubled-K supply increased L-malic acid content in the early-ripening phase, and increased K and magnesium concentrations in the late-ripening phase. Doubled-K supply reduced the ratio of K to sodium in later ripening phases, suggesting that the accumulation of K relative to sodium was limited in more mature berries supplied with extra K. Pericarp water percentage, sugar, K and ATP were correlated in both treatments, indicating links between hydration, solute transport and energy in maturing berries. In a separate rootstock trial over the two growing seasons, Shiraz scions grafted onto 420-A rootstock produced berries with lower K concentration and content than those grafted onto Ramsey or Ruggeri-140 rootstocks and own-rooted vines. This study demonstrated that the K supply and berry ripening phase impacted the berry K level. Increased potassium (K) concentration in grape (Vitis vinifera) berries is associated with loss of acidity and high sugar content in juice. This study demonstrated that the K supply to Shiraz and berry ripening phase could impact the berry attributes and chemical composition at harvest, associated with the linkages between water, sugar, K and ATP. From this study, we suggest that grape berry maturation and composition management may be beneficial. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) faces challenges to yield and quality due to urbanisation, deforestation and climate change, which has exacerbated high night temperature (HNT). This review explores the impacts of HNT on the physiological, molecular and agronomic aspects of rice growth. Rise in minimum temperature threatens a potential 41% reduction in rice yield by 2100. HNT disrupts rice growth stages, causing reduced seed germination, biomass, spikelet sterility and poor grain development. Recent findings indicate a 4.4% yield decline for every 1°C increase beyond 27°C, with japonica ecotypes exhibiting higher sensitivity than indica. We examine the relationships between elevated CO2, nitrogen regimes and HNT, showing that the complexity of balancing positive CO2 effects on biomass with HNT challenges. Nitrogen enrichment proves crucial during the vegetative stage but causes disruption to reproductive stages, affecting grain yield and starch synthesis. Additionally, we elucidate the impact of HNT on plant respiration, emphasising mitochondrial respiration, photorespiration and antioxidant responses. Genomic techniques, including CRISPR-Cas9, offer potential for manipulating genes for HNT tolerance. Plant hormones and carbohydrate enzymatic activities are explored, revealing their intricate roles in spikelet fertility, grain size and starch metabolism under HNT. Gaps in understanding genetic factors influencing heat tolerance and potential trade-offs associated with hormone applications remain. The importance of interdisciplinary collaboration is needed to provide a holistic approach. Research priorities include the study of regulatory mechanisms, post-anthesis effects, cumulative HNT exposure and the interaction between climate variability and HNT impact to provide a research direction to enhance rice resilience in a changing climate. We explore the impact of high night temperature (HNT) on rice phenomics, physiology and grain yield. From accelerated vegetative growth to changes in reproductive phases and enzymatic activities, we review how HNT affects rice in elevated CO2 and nitrogen environments to provide insights into photosynthesis, respiration and hormonal regulation, and their effect on grain yield and quality. This article belongs to the Collection Functional Genomics for Developing Climate Resilient Crops. [ABSTRACT FROM AUTHOR]

Rapid wound healing is crucial in protecting sweet potatoes (Ipomoea batatas) against infection, water loss and quality deterioration during storage. The current study investigated how acibenzolar-S-methyl (ASM) treatment influenced wound healing in harvested sweet potatoes by investigating the underlying mechanism. It was found that ASM treatment of wounded sweet potatoes induced a significant accumulation of lignin at the wound sites, which effectively suppressed weight loss. After 4 days of healing, the lignin content of ASM-treated sweet potatoes was 41.8% higher than that of untreated ones, and the weight loss rate was 20.4% lower. Moreover, ASM treatment increased the ability of sweet potatoes to defend against wounding stress through enhancing processes such as increased production of reactive oxygen species (ROS), activation of enzymes involved in the ROS metabolism (peroxidase, superoxide dismutase and catalase) and phenylpropanoid pathway (phenylalanine ammonia lyase, cinnamate-4-hydroxylase, 4-coumarate-CoA ligase and cinnamyl alcohol dehydrogenase), and intensive synthesis of phenolics and flavonoids. These results suggest that treating harvested sweet potatoes with ASM promotes wound healing through the activation of the ROS metabolism and phenylpropanoid pathway. Mechanical damage during harvest, handling and transportation can cause wounding in sweet potatoes (Ipomoea batatas). Wounds provide an access point for pathogens to infect the sweet potato, leading to rotting and quality deterioration during storage. Wound healing plays an important role in maintaining postharvest quality and shelf life of sweet potato. Our data showed that postharvest ASM treatment effectively promoted wound healing of sweet potatoes. These results provide theoretical basis for improving the storage quality of wounded sweet potatoes. [ABSTRACT FROM AUTHOR]

Detrimental effects of salinity could be mitigated by exogenous zinc (Zn) application; however, the mechanisms underlying this amelioration are poorly understood. This study demonstrated the interaction between Zn and salinity by measuring plant biomass, photosynthetic performance, ion concentrations, ROS accumulation, antioxidant activity and electrophysiological parameters in barley (Hordeum vulgare L.). Salinity stress (200 mM NaCl for 3 weeks) resulted in a massive reduction in plant biomass; however, both fresh and dry weight of shoots were increased by ~30% with adequate Zn supply. Zinc supplementation also maintained K+ and Na+ homeostasis and prevented H2O2 toxicity under salinity stress. Furthermore, exposure to 10 mM H2O2 resulted in massive K+ efflux from root epidermal cells in both the elongation and mature root zones, and pre-treating roots with Zn reduced ROS-induced K+ efflux from the roots by 3–4-fold. Similar results were observed for Ca2+. The observed effects may be causally related to more efficient regulation of cation-permeable non-selective channels involved in the transport and sequestration of Na+, K+ and Ca2+ in various cellular compartments and tissues. This study provides valuable insights into Zn protective functions in plants and encourages the use of Zn fertilisers in barley crops grown on salt-affected soils. Exogenous Zn supply improve salinity tolerance in barley (Hordeum vulgare) by significant reduction in shoot Na+ load and improved K+ retention in leaf root and mesophyll cells. The above effects are attributed to regulation of non-selective channels involved in transport of Na+, K+ and Ca2+ across cellular membranes. [ABSTRACT FROM AUTHOR]

Cassava (Manihot esculenta Crantz), an important tropical crop, is affected by extreme climatic events, including rising CO2 levels. We evaluated the short-term effect of elevated CO2 concentration (ECO2) (600, 800 and 1000 ppm) on the photosynthetic efficiency of 14 cassava genotypes. ECO2 significantly altered gaseous exchange parameters (net photosynthetic rate (P n), stomatal conductance (g s), intercellular CO2 (C i) and transpiration (E)) in cassava leaves. There were significant but varying interactive effects between ECO2 and varieties on these physiological characteristics. ECO2 at 600 and 800 ppm increased the P n rate in the range of 13–24% in comparison to 400 ppm (ambient CO2), followed by acclimation at the highest concentration of 1000 ppm. A similar trend was observed in g s and E. Conversely, C i increased significantly and linearly across increasing CO2 concentration. Along with C i, a steady increase in water use efficiency [WUEintrinsic (P n/ g s) and WUEinstantaneous (P n/ E)] across various CO2 concentrations corresponded with the central role of restricted stomatal activity, a common response under ECO2. Furthermore, P n had a significant quadratic relationship with the ECO2 (R 2 = 0.489) and a significant and linear relationship with C i (R 2 = 0.227). Relative humidity and vapour pressure deficit during the time of measurements remained at 70–85% and ~0.9–1.31 kPa, respectively, at 26 ± 2°C leaf temperature. Notably, not a single variety exhibited constant performance for any of the parameters across CO2 concentrations. Our results indicate that the potential photosynthesis can be increased up to 800 ppm cassava varieties with high sink capacity can be cultivated under protected cultivation to attain higher productivity. Cassava (Manihot esculenta Crantz) exhibited a positive response to elevated CO2 levels (ranging from 600 to 1000 ppm) compared to the ambient concentration of 400 ppm CO2. Most of the photosynthetic parameters showed steady improvement up to 800 ppm, followed by down-regulation at the highest concentration. The physiological water use efficiency of fourteen cassava varieties was enhanced at 1000 ppm due to restricted stomatal activity and reduced transpiration rate. [ABSTRACT FROM AUTHOR]

The two stresses of weed competition and salt salinity lead to crop yield losses and decline in the productivity of agricultural land. These constraints threaten the future of food production because weeds are more salt stress tolerant than most crops. Climate change will lead to an increase of soil salinity worldwide, and possibly exacerbate the competition between weeds and crops. This aspect has been scarcely investigated in the context of weed-crop competition. Therefore, we conducted a field experiment on green beans (Phaseolus vulgaris) to investigate the combined impact of weed competition and salt stress on key morpho-physiological traits, and crop yield. We demonstrated that soil salinity shifted weed composition toward salt tolerant weed species (Portulaca oleracea and Cynodon dactylon), while it reduced the presence of lower tolerance species. Weed competition activated adaptation responses in green bean such as reduced leaf mass per area and biomass allocation to the stem, unchanged stomatal density and instantaneous water use efficiency, which diverge from those that are typically observed as a consequence of salt stress. The morpho-physiological modifications caused by weeds is attributed to the alterations of light intensity and/or quality, further confirming the pivotal role of the light in crop response to weeds. We concluded that higher yield loss caused by combined salt stress and weed competition is due to impaired morpho-physiological responses, which highlights the negative interaction between salt stress and weed competition. This phenomenon will likely be more frequent in the future, and potentially reduce the efficacy of current weed control methods. Environmental stresses cause severe yield losses. In the field, these stresses occur contextually, leading to unpredictable outcomes in terms of crop productivity. Soil/water salinity will expand in the future due to climate change, and weed control will become harder due to herbicide resistance. We studied the combined effect of weed competition and salt stress on the yield of green beans (Phaseolus vulgaris), finding that the morpho-physiological adaptations induced by weed competition impair plant ability to tolerate salt stress. [ABSTRACT FROM AUTHOR]

Seed dormancy ensures plant survival but many mechanisms remain unclear. A high-throughput RNA-seq analysis investigated the mechanisms involved in the establishment of dormancy in dimorphic seeds of Xanthium strumarium (L.) developing in one single burr. Results showed that DOG1, the main dormancy gene in Arabidopsis thaliana L., was over-represented in the dormant seed leading to the formation of two seeds with different cell wall properties. Less expression of DME/EMB1649, UBP26, EMF2, MOM, SNL2, and AGO4 in the non-dormant seed was observed, which function in the chromatin remodelling of dormancy-associated genes through DNA methylation. However, higher levels of ATXR7/SDG25, ELF6, and JMJ16/PKDM7D in the nondormant seed that act at the level of histone demethylation and activate germination were found. Dramatically lower expression in the splicing factors SUA, PWI, and FY in non-dormant seed may indicate that variation in RNA splicing for ABA sensitivity and transcriptional elongation control of DOG1 is of importance for inducing seed dormancy. Seed size and germination may be influenced by respiratory factors, and alterations in ABA content and auxin distribution and responses. TOR (a serine/threonine-protein kinase) is likely at the centre of a regulatory hub controlling seed metabolism, maturation, and germination. Over-representation of the respirationassociated genes (ACO3, PEPC3, and D2HGDH) was detected in non-dormant seed, suggesting differential energy supplies in the two seeds. Degradation of ABA biosynthesis and/or proper auxin signalling in the large seed may control germinability, and suppression of endoreduplication in the small seed may be a mechanism for cell differentiation and cell size determination. [ABSTRACT FROM AUTHOR]

In vascular plants, bryophytes and algae, the photosynthetic light reaction takes place in the thylakoid membrane where two transmembrane supercomplexes PSII and PSI work together with cytochrome b6f and ATP synthase to harvest the light energy and produce ATP and NADPH. Vascular plant PSI is a 600-kDa protein--pigment supercomplex, the core complex of which is partly surrounded by peripheral light-harvesting complex I (LHCI) that captures sunlight and transfers the excitation energy to the core to be used for charge separation. PSI is unique mainly in absorption of longer-wavelengths than PSII, fast excitation energy transfer including uphill energy transfer, and an extremely high quantum efficiency. From the early 1980s, a lot of effort has been dedicated to structural and functional studies of PSI--LHCI, leading to the current understanding of how more than 200 cofactors are kept at the correct distance and geometry to facilitate fast energy transfer in this supercomplex at an atomic level. In this review, we review the history of studies on vascular plant PSI--LHCI, summarise the present research progress on its structure, and present some new and further questions to be answered in future studies. [ABSTRACT FROM AUTHOR]

Several recent papers have shown that in grapevine (Vitis vinifera L.), interpretation of responses to drought can differ depending upon the parameter chosen to express water use efficiency (WUE). In the present paper, a series of WUE expressions, including physiological and agronomical, were compared in potted grapevines (Vitis vinifera L. cv. Sangiovese) that were either well-watered (WW) or subjected to progressive drought before veraison (WS) by supplying decreasing fractions (i.e. 70%, 50% and 30% of daily vine transpiration (Trd) determined gravimetrically before vines were fully rewatered. Although single-leaf intrinsic and instantaneous WUE increased with water stress severity, seasonal and whole-canopy WUE were similar to that before stress, at 70% Trd and upon rewatering, but dropped during severe water stress. WUE calculated as mass of DW stored in annual biomass (leaves, canes and bunches) per litre of water used did not differ on a seasonal basis, whereas WS plants showed lower must soluble solids at harvest, and unchanged colour and phenolic concentration in spite of smaller berries with higher relative skin growth. Results confirm that whole-canopy WUE is a much better index than any single-leaf based WUE parameter for extrapolation to agronomic WUE and actual grape composition. In our specific case study, it can be recommended that water supply to drought-stressed Sangiovese grapevines before veraison should not be lower than 70% of daily vine water use. How grapevines (Vitis vinifera L.) use irrigation under drought needs to be determined. Previous work shows contradictory results regarding the method used. Single-leaf and whole-canopy methods for assessing water use efficiency (WUE) were compared in V. vinifera cv. Sangiovese subjected to progressive water deficit before veraison. Single-leaf WUE assessment was poorly correlated with yield and grape composition, whereas whole-canopy assessment was more reliable. Guidelines were that not less than 70% of daily water use should be supplied to Sangiovese vines before veraison. [ABSTRACT FROM AUTHOR]

A meta-analysis of 520 reports published during the last 20 years on transgenic and mutant plants generated towards drought resistance revealed a total of at least 487 tested transgenic plants involving at least 100 genes claimed to be functional towards drought resistance. During this period, the rate of reported new experimental transgenic model or crop plants for drought resistance has been increasing exponentially. Despite these numbers, qualified sources of information indicate a very limited impact on global dryland agriculture, whereas the genetically modified (GM) market hardly recognises drought-resistant GM cultivars. This paper discusses possible reasons for the limited impact of genomics on the delivery of drought-resistant cultivars, which are beyond issues of regulation, propriety or commercialisation. These reasons are mainly tied to scientific and methodological problems in drought stress gene expression work and the functional genomics protocols used to identify drought resistance. Insufficient phenotyping of experimental transgenic plants for drought resistance often does not allow true conclusions about the real function of the discovered genes towards drought resistance. The discussion is concluded by proposing an outline of a minimal set of tests that might help us resolve the real function of discovered genes, thus bringing the research results down to earth. [ABSTRACT FROM AUTHOR]

The effect of differential drying rates on desiccation tolerance in Physcomitrella patens (Hedw.) Bruch & Schimp. is examined. In order to provide more evidence as to the status of desiccation tolerance in P. patens, a system was designed that allowed alteration of the rate of water loss within a specific relative humidity. An artificial substrate consisting of layers of wetted filter paper was used to slow the drying process to as long as 284 h, a significant increase over the commonly used method of exposure (saturated salt solution). By slowing the rate of drying, survival rates and chlorophyll fluorescence parameters improved, and tissue regeneration time was faster. These results indicate a trend where the capacity for desiccation tolerance increases with slower drying, and reveal a much stronger capacity for desiccation tolerance in P. patens than was previously known. [ABSTRACT FROM AUTHOR]

Crassulacean acid metabolism (CAM) is a celebrated example of convergent evolution in plant ecophysiology. However, many unanswered questions surround the relationships among CAM, anatomy and morphology during evolutionary transitions in photosynthetic pathway. An excellent group in which to explore these issues is the Bromeliaceae, a diverse monocot family from the Neotropics in which CAM has evolved multiple times. Progress in the resolution of phylogenetic relationships among the bromeliads is opening new and exciting opportunities to investigate how evolutionary changes in leaf structure has tracked, or perhaps preceded, photosynthetic innovation. This paper presents an analysis of variation in leaf anatomical parameters across 163C3 and CAM bromeliad species, demonstrating a clear divergence in the fundamental aspects of leaf structure in association with the photosynthetic pathway. Most strikingly, the mean volume of chlorenchyma cells of CAM species is 22 times higher than that of C3 species. In two bromeliad subfamilies (Pitcairnioideae and Tillandsioideae), independent transitions from C3 to CAM are associated with increased cell succulence, whereas evolutionary trends in tissue thickness and leaf air space content differ between CAM origins. Overall, leaf anatomy is clearly and strongly coupled with the photosynthetic pathway in the Bromeliaceae, where the independent origins of CAM have involved significant anatomical restructuring. [ABSTRACT FROM AUTHOR]

Trapa plants (Trapaceae) have an inflated leaf petiole called a spongy airbag. The aims of this study were to assess the involvement of programmed cell death (PCD) in the process of inflated leaf petiole morphogenesis. In this paper, light and transmission electron microscopy (TEM) were used to investigate cytological events and the development of inflated leaf petiole. During this process, the inflated leaf petiole of Trapa pseudoincisa L. undergoes a developmental process, changing from solid to hollow phase. Debris from the degraded cells was seldom observed in the transverse sections of leaf petioles, but some degraded cells with an abnormal morphology were observed in longitudinal sections. Cytoplasmic changes, such as disrupted vacuoles, degraded plastids, and the emergence of secondary vacuoles were observed during leaf petiole morphogenesis. In addition, gel electrophoresis and TUNEL assays were used to evaluate DNA cleavage during petiole morphogenesis. DNA internucleosomal cleavage and TUNEL-positive nuclei indicate that the typical PCD features of DNA cleavage occurred early in the process. These results revealed that PCD plays a critical role in inflated leaf petiole morphogenesis. Additionally, a trans-disciplinary systems approach is required that recognises the necessity for integration of cytological and molecular characteristics for identification of aerenchyma type. [ABSTRACT FROM AUTHOR]

Plant signalling is a set of phenomena that serves the transduction of external and internal signals into physiological responses such as modification of enzyme activity, cytoskeleton structure or gene expression. It operates at the level of cell compartments, whole cells, tissues, organs or even plant communities. To achieve this, plants have evolved a network of signalling proteins including plasma membrane receptors and ion transporters, cascades of kinases and other enzymes as well as several second messengers such as cytosolic calcium (Ca2+), reactive oxygen/nitrogen species (ROS/RNS), cyclic nucleotides (cAMP and cGMP) and others. Overall, these systems recognise and decode environmental signals and co-ordinate ontogeny programs. This paper summarises recent progress in the field of plant signalling, which was a major theme of the 4th International Symposium on Plant Signalling and Behaviour, 2016, in Saint Petersburg, Russia. Several novel hypotheses and concepts were proposed during this meeting. First, the concept of ROS-Ca2+ hubs has found further evidence and acceptance. This concept is based on reciprocal activation of NADPH oxidases by cytosolic Ca2+ on the one hand, and Ca2+-permeable channels that are activated by NADPH-produced ROS. ROS-Ca2+ hubs enhance the intensity and duration of originally weak Ca2+ and ROS signals. Hubs are directly involved in ROS- and Ca2+-mediated physiological reactions, such as stress response, growth, programmed cell death, autophagy and long-distance signalling. Second, recent findings have widened the list of cyclic nucleotide-regulated processes and strengthened the biochemical basis of cyclic nucleotide biochemistry by exploring cyclase activities of new receptors such as the Phytosulfokine Receptor 1, the pathogen peptide 1 receptor (atPepR1), the brassinosteroid BRI1 receptor and the cell wall-associated kinase like 10. cGMP and cAMP signalling has demonstrated strong link to Ca2+ signalling, via cyclic nucleotide-gated Ca2+-permeable ion channels (CNGCs), and to ROS and RNS via their nitrosylated forms. Third, a novel role for cytosolic K+ as a regulator of plant autophagy and programmed cell death has emerged. The cell death-associated proteases and endonucleases were demonstrated to be activated by a decrease of cytosolic K+ via ROS-induced stimulation of the plasma membrane K+ efflux channel GORK. Importantly, the origin of ROS for induction of autophagy and cell death varies in different tissues and comprises several pools, including NADPH oxidases, peroxidases, photosynthetic and respiratory electron-transporting chains and peroxisomal enzymes. The peroxisome pool is the 'latest' addition to established cellular ROS-producing machineries and is dependent on the state and abundance of catalase in this compartment. Finally, new aspects of phytohormone signalling, such as regulation of root hydraulic pressure by abscisic acid and rate of mitosis by cytokinins, as well as localising cytokinin receptors in endoplasmic reticulum, are reported. Other observations suggest that melatonin is a hormone-like substance in plants, because it targets Ca2+, ROS and RNS. [ABSTRACT FROM AUTHOR]

The world is currently experiencing dramatic increases in flood events impacting on natural vegetation and crops. Flooding often results in low O2 status in root tissues during waterlogging, but sometimes also in shoot tissues when plants become completely submerged. Plants possess a suite of traits enabling tissue aeration and/or adjusted metabolism during hypoxia or even in the absence of O2. This special issue of Functional Plant Biology presents key papers for plant scientists on the quest to further address and improve flood tolerance of terrestrial plants. The papers address low O2 responses in roots, shoots or whole plants in controlled laboratory conditions or in the field situation using natural wetland plants as models as well as economically important crops, such as rice, wheat and barley. The studies advance our understanding of low O2 responses in plant tissues as caused by O2 shortage during flooding. However, in most instances, submergence not only leads to hypoxic or anoxic tissues, but inundation in water also results in accumulation of CO2 and the important plant hormone ethylene. Thus, carefully designed laboratory studies are often needed to unravel the mechanistic relationships between a combined decline in O2 followed by increases in CO2 and ethylene at tissue as well as on the cellular level. [ABSTRACT FROM AUTHOR]