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Leaf spot and viral diseases are the most frequently occurring leaf problems in Taizishen production. In this study, we examined the controlling role played by the co-application of tetramycin and low dose tebuconazole·azoxystrobin against leaf spot and viral diseases in Taizishen, investigating its resistance, electrophysiological information, growth and quality. Among them, electrophysiological information indicators include electrical signals [intrinsic capacitance (IC), resistance (IR), impedance (IZ), capacitive reactance (IXc), and inductive reactance (IXL)], intracellular water metabolism, nutrient transport, and plant metabolic activity. The results indicate that 0.3% tetramycin 1000-time + 75% tebuconazole·azoxystrobin 2000-time diluent controlled leaf spot and viral diseases the best, with protection effects of 90.03%~90.46% and 71.67%~73.08% at 15~30 days after the last fungicide application, respectively. These values are obviously higher than those treated with high doses of tetramycin or tebuconazole·azoxystrobin alone. Concurrently, their combined application could notably enhance total soluble flavonoids, total soluble phenols, protective enzyme activity, IC, intracellular water metabolism, nutrient transport, and metabolic activity, while reducing its MDA, IR, IZ, IXc, and IXL. Moreover, their co-application also could obviously ameliorate photosynthesis, biomass, agronomic trait, and root growth and quality, as well as actually reduce tebuconazole·azoxystrobin input. Additionally, the control effects of leaf spot and viral diseases in Taizishen treated by their combined application exhibited significant correlations with its disease resistance, electrophysiology, photosynthesis, growth, and quality parameters. This study highlights the combined application of low-dosage tebuconazole·azoxystrobin and tetramycin as a practicable measure for controlling leaf spot and viral diseases in Taizishen, promoting its resistance, growth, and quality, as well as reducing chemical pesticide application. [ABSTRACT FROM AUTHOR]

Background: Abiotic stressors such as heavy metals and nanoparticles pose significant challenges to sustainable agriculture, with copper oxide nanoparticles (CuO NPs) known to inhibit root growth and induce oxidative stress in plants. While silica nanoparticles (SiO2 NPs) have been shown to increase abiotic stress tolerance, their role in mitigating CuO NP-induced stress in crops, especially monocots, remains poorly understood. This study addresses this critical knowledge gap by investigating how SiO2 NP pretreatment modulates CuO NP-induced stress responses, with a particular focus on root growth inhibition and nitro-oxidative stress pathways. Results: Using an in vitro semihydroponic system, seeds were pretreated with varying concentrations of SiO2 NPs (100–800 mg/L) before exposure to CuO NPs at levels known to inhibit root growth by 50%. SiO2 NP pretreatment alleviated CuO NP-induced root growth inhibition in sorghum, wheat, and rye but intensified it in triticale. These responses are associated with species-specific alterations in reactive signaling molecules, including a reduction in nitric oxide levels and an increase in hydrogen sulfide in sorghum, a decrease in superoxide anion levels in rye, and elevated hydrogen peroxide levels in wheat. Protein tyrosine nitration, a marker of nitro-oxidative stress, was reduced in most cases, further indicating the stress-mitigating role of SiO2 NPs. These signaling molecules were selected for their established roles in mediating oxidative and nitrosative stress responses under abiotic stress conditions. Conclusions: SiO2 NP pretreatment modulates CuO NP-induced stress responses through species-specific regulation of reactive oxygen and nitrogen species, demonstrating its potential as a tool for enhancing crop resilience. These findings advance the understanding of nanoparticle‒plant interactions and provide a foundation for future applications of nanotechnology in sustainable agriculture. Clinical trial number: Not applicable. Highlights: SiO2 NP pretreatment counteracts CuO NP-induced stress in sorghum, wheat, and rye roots. Species-specific effects on the ROS and RNS levels under the SiO2 and CuO NP treatments. CuO NP stress increases protein nitration, which is reduced by SiO2 NPs in most cases. NPs impact plant stress pathways, revealing complex mitigation mechanisms. [ABSTRACT FROM AUTHOR]

In Mexico, the center of maize origin (Zea mays ssp. mays), there are landraces from the highlands that develop extensive aerial root systems which secrete a carbohydrate-rich mucilage. This mucilage produces a favorable environment for nitrogenase activity by diazotrophs. This plant-microbial interaction enables the fixation of nitrogen (N) from the atmosphere, reducing the required N that otherwise must come from the soil and/or fertilizers. The objective of this research was to investigate the degree to which other landraces of maize and nutrient management affect aerial root growth and the ability of maize to perform and benefit from N2 fixation. In two replicated field experiments in Columbus, Ohio, USA in 2019 and 2020, we planted 21 maize landraces and three improved varieties with and without fertilizer to measure their growth, production of aerial roots, and rate of atmospheric N2 fixation using the 15N natural abundance method. Maize accessions varied in the growth rate and number of nodes with aerial roots. Up to 36% of plant N was derived from the atmosphere, with values varying by accession, the reference plant used, and the fertilizer level. Moreover, there was a positive relationship between early growth parameters and numbers of nodes with aerial roots, which, in turn, predicted the amount of N derived from the atmosphere. Thus, larger seedlings may experience enhanced root growth and thereby benefit more from N fixation. By phenotyping a diverse set of maize accessions with and without fertilizer, this study explores both environmental and quantitative genetic variation in the traits involved in N fixation capacity, clarifying that N fixation found in the Sierra Mixe landrace is more broadly distributed than previously thought. In sum, farmers stewarding genetic diversity in a crop center of origin have preserved traits essential for biological symbioses that contribute to maize's nutrient requirements. These traits may enable maize crops grown by Mexican farmers, and farmers globally, to benefit from N fixation from the atmosphere. [ABSTRACT FROM AUTHOR]

Plants have developed complex mechanisms to perceive, transduce, and respond to environmental signals, such as light, which are essential for acquiring and allocating resources, including nitrogen (N). This review delves into the complex interaction between light signals and N metabolism, emphasizing light-mediated regulation of N uptake and assimilation. Firstly, we examine the details of light-mediated regulation of N uptake and assimilation, focusing on the light-responsive activity of nitrate reductase (NR) and nitrate transporters. Secondly, we discuss the influence of light on N-dependent developmental plasticity, elucidating how N availability regulates crucial developmental transitions such as flowering time, shoot branching, and root growth, as well as how light modulates these processes. Additionally, we consider the molecular interaction between light and N signalling, focusing on photoreceptors and transcription factors such as HY5, which are necessary for N uptake and assimilation under varying light conditions. A recent understanding of the nitrate signalling and perception of low N is also highlighted. The in silico transcriptome analysis suggests a reprogramming of N signalling genes by shade, and identifies NLP7, bZIP1, CPK30, CBL1, LBD37, LBD38, and HRS1 as crucial molecular regulators integrating light-regulated N metabolism. [ABSTRACT FROM AUTHOR]

To elucidate the molecular function of SHORT AND SWOLLEN ROOT1 (SSR1), we screened for suppressors of the ssr1-2 (sus) was performed and identified over a dozen candidates with varying degrees of root growth restoration. Among these, the two most effective suppressors, sus1 and sus2, resulted from G87D and T55M single amino acid substitutions in HSCA2 (At5g09590) and ISU1 (At4g22220), both crucial components of the mitochondrial iron-sulfur (Fe-S) cluster assembly machinery. SSR1 displayed a robust cochaperone-like activity and interacted with HSCA2 and ISU1, facilitating the binding of HSCA2 to ISU1. In comparison to the wild-type plants, ssr1-2 mutants displayed increased iron accumulation in root tips and altered expression of genes responsive to iron deficiency. Additionally, the enzymatic activities of several iron-sulfur proteins and the mitochondrial membrane potential were reduced in ssr1-2 mutants. Interestingly, SSR1 appears to be exclusive to plant lineages and is induced by environmental stresses. Although HSCA2G87D and ISU1T55M can effectively compensate for the phenotypes associated with SSR1 deficiency under favorable conditions, their compensatory effects are significantly diminished under stress. Collectively, SSR1 represents a new and significant component of the mitochondrial Fe-S cluster assembly (ISC) machinery. It may also confer adaptive advantages on plant ISC machinery in response to environmental stress. Author summary: Iron-sulfur (Fe-S) clusters are crucial components found in many proteins that play essential roles in various biological processes. The machinery responsible for making these clusters in mitochondria, known as ISC biosynthesis, has its origins in bacteria and remained largely unchanged through evolution. However, understanding of specific regulators that control Fe-S cluster production in plants is still limited. In this study, we identified a unique protein in plants, SSR1, which acts as a cochaperone. SSR1 facilitates the interaction between the two critical proteins, HSCA2 and ISU1, a necessary process for the release of Fe-S clusters from their scaffold. We also showed that SSR1 has evolved alongside the ISC biosynthetic machinery and that mutations in HSCA2 and ISU1 can compensate for its absence. This highlights the synergistic relationship between SSR1 and other components of the ISC machinery. Overall, this research uncovers a novel component of the ISC biosynthetic system and shows how it varies between plants, animals, and microorganisms. [ABSTRACT FROM AUTHOR]

This work presents an imaging testing system (software and hardware) that can generate repeatable images through a stabilized port in the soil for processes known to change with time. The system includes (i) a stabilized port in the ground made of standard PVC pipe, with sections lined with a borosilicate glass tube, and (ii) a digital imaging instrument to survey the optically transparent portion of the stabilized port. The instrument uses a probe containing a digital camera and two light sources, one using white lights and one using ultraviolet (UV) lights (365 nm). The main instrument controls the probe using a cable within the stabilized port to take overlapping pictures of the soil under the different light sources. Two examples are provided, one to document the distribution of soil and groundwater contaminants known as non-aqueous phase liquids (NAPL, which include petroleum) at variable water saturation levels and a second one to monitor the growth of a plant over a 2-week interval. In both examples, the system successfully identified critical changes in soil processes and showed a resolution of approximately 15 µm (in the order of the thickness of a human hair), demonstrating the potential for repeated imaging of soil processes known to experience temporal changes. Both examples are illustrative, as additional applications might be possible. The novelty of this system lies in its ability to generate repeated measurements at larger depths than the current shallow systems installed by hand. [ABSTRACT FROM AUTHOR]

Wild soybean, which has many desirable traits, such as adaptability to climate change-related stresses, is a valuable resource for expanding the narrow genetic diversity of cultivated soybeans. Plants require roots to adapt to different environments and optimize water and nutrient uptake to support growth and facilitate the storage of metabolites; however, it is challenging and costly to evaluate root traits under field conditions. Previous studies of quantitative trait loci (QTL) have been mainly based on cultivated soybean populations. In this study, an interspecific mapping population from a cross between wild soybean 'PI483463' and cultivar 'Hutcheson' was used to investigate QTLs associated with root traits using image data. Our results showed that 39 putative QTLs were distributed across 10 chromosomes (chr.). Seventeen of these were clustered in regions on chr. 8, 14, 15, 16, and 17, accounting for 19.92% of the phenotypic variation. We identified five significant QTL clusters influencing root-related traits, such as total root length, surface area, lateral total length, and number of tips, across five chr., with favorable alleles from both wild and cultivated soybeans. Furthermore, we identified eight candidate genes controlling these traits based on functional annotation. These genes were highly expressed in root tissues and directly or indirectly affected soybean root growth, development, and stress responses. Our results provide valuable insights for breeders aiming to optimize soybean root traits and leveraging genetic diversity from wild soybean species to develop varieties with improved root morphological traits, ultimately enhancing overall plant growth, productivity, and resilience. [ABSTRACT FROM AUTHOR]

Plants emit green leaf volatiles (GLVs) in response to biotic and abiotic stress. Receiver plants perceive GLVs as alarm cues resulting in activation of defensive or protective mechanisms. While this is well documented, it is not known how GLVs are perceived by receiver cells and what the structural determinants are for GLV activity. We tested whether the carbon chain length in (Z)-3-fatty alcohols with four to nine carbons and the double bonds in six-carbon alcohols contribute to bioactivity. In Solanum peruvianum suspension-cultured cells we found that (Z)-3-fatty alcohols, except (Z)-3-butenol, induce medium alkalinization and MAP kinase phosphorylation, two signaling responses often tied to the perception of molecular patterns that function in plant immunity and resistance to herbivores. In tomato (S. lycopersicum) seedlings, we found that (Z)-3-fatty alcohols induce inhibition of root growth. In both signaling and physiological responses, (Z)-3-octenol and (Z)-3-nonenol had a higher bioactivity than (Z)-3-heptenol and (Z)-3-hexenol, with (Z)-3-butenol only being active in root growth assays. Bioactivity correlated not only with chain length but also with lipophilicity of the fatty alcohols. The natural GLVs (E)-2-hexenol and the saturated 1-hexanol exhibited a higher bioactivity in pH assays than (Z)-3-hexenol, indicating that the presence and position of a double bond also contributes to bioactivity. Our results indicate that perceiving mechanisms for (Z)-3-fatty alcohols show a preference for longer chain fatty alcohols or that longer chain fatty alcohols are more accessible to receptors. [ABSTRACT FROM AUTHOR]

Bacillus velezensis S141 helps soybean establish specific symbiosis with strains of Bradyrhizobium diazoefficiens to form larger nodules and improve nitrogen fixation efficiency. In this study, we found that the dry weight of soybean roots increased significantly in the presence of S141 alone under drought conditions. Hence, S141 improved the root growth of soybean under limited water supply conditions. S141 can produce some auxin, which might be involved in the improved nodulation. Inactivating IPyAD of S141, which is required for auxin biosynthesis, did not alter the beneficial effects of S141, suggesting that the root growth was independent of auxin produced by S141. Under drought conditions, soybean exhibited some responses to resist osmotic and oxidative stresses; however, S141 was relevant to none of these responses. Although the mechanism remains unclear, S141 might produce some substances that stimulate the root growth of soybean under drought conditions. [ABSTRACT FROM AUTHOR]

New techniques for the rapid multiplication of cassava (Manihot esculenta Crantz) planting materials have been developed. However, information regarding their cultivation in fields is limited. A recent study was conducted to assess the vegetative and root yields of cassava varieties raised from low tunnel and open field nurseries. The treatments were arranged in a randomized complete block design, using a split–split plot layout. Cassava varieties served as the main plot factor, cutting sizes as the sub-plot factor, and planting methods as the sub-sub-plot factor, with three replications for each treatment. Results revealed that cassava varieties, cutting size, and planting methods differed significantly (p < .001) on vegetative growth and root yields. Plants raised from low tunnel had higher plant height (157.2 cm), number of main stems (2.9), number of primary (4.7) and secondary (6.8) branches compared to plants raised in open fields. ‘TARICAS4’ raised from low tunnels had the highest fresh root yields of 10.8 t/ha and dry matter content of 53% as compared to other varieties. Therefore, low tunnels should be used in mass cassava plantlet production to improve vegetative development and root yields. [ABSTRACT FROM AUTHOR]

Roots exhibit plasticity in morphology and physiology when exposed to fluctuating nutrient and water availability. However, the dynamics of daily timescale adjustments to changes in water availability are unclear, and experimental evidence of the rates of such adjustments is needed. In this study, we investigated how the root system responds within days to a sudden and localized increase in soil moisture ("hydromatching"). Root systems of maize plants were grown in soil columns divided into four layers by vaseline barriers and continuously monitored using magnetic resonance imaging (MRI) technology. We found that, within 48 h after application of water pulses in a given soil layer, root growth rates in that layer increased, while root growth rates in other layers decreased. Our results indicate local root growth was guided by local changes in soil moisture and potentially even by changes in soil moisture occurring in other parts of the soil profile, which would result in a coordinated response of the entire root system. Hydromatching in maize appears to be a dynamic and reversible phenomenon, for which the investment in biomass is continuously promoted in wet soil volumes and/or halted in drier soil volumes. This sheds new light onto the plasticity of root systems of maize plants and their ability to adjust to local and sudden changes in soil moisture, as would be expected due to patchy infiltration after rainfall or irrigation events. [ABSTRACT FROM AUTHOR]

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The widespread concern over nanoplastics (NPs) has prompted extensive research into their environmental impact. Concurrently, the study examined the combined toxicity of PS NPs and cadmium (Cd) on wheat. As indicated by the results of in situ Micro-ATR/FTIR, the aging process of PS NPs (50 nm) led to an increase in carbonyl and hydroxyl groups on their surface, enhancing hydrophilicity and consequently, the adsorption capacity for Cd. The toxicity assessment, measured by the impact on wheat leaf and root biomass after 7 d culture, revealed that pristine PS NPs with concentrations of 0–5000 mg·kg⁻¹ had a negligible effect on Cd toxicity to wheat leaves. However, aged PS NPs significantly intensified the inhibitory effect on wheat root growth, particularly at low Cd concentrations (≤ 5.0 mg·kg⁻¹). This synergistic toxicity between aged PS NPs and Cd is suspected to stem from the increased bioaccumulation of Cd in wheat, likely facilitated by the aged NPs. Thus, the study shed light on the aging behavior of soil surface NPs and its implications for environmental risk assessment. [ABSTRACT FROM AUTHOR]

This study evaluated dragon fruit propagation using various concentrations of indole-3-butyric acid (IBA) and cutting lengths over two seasons (March and July 2022). Results revealed that 30 cm cuttings treated with 1000 ppm IBA had the earliest shoot emergence (14.8 days in March) and the highest shoot counts (3.2 per cutting in March, 2.8 in July). The same treatment achieved maximum shoot fresh (222.7 g) and dry weights (66.8 g). Root parameters improved significantly, with a mean root count of 26.8 roots per cutting in 30 cm cuttings and maximum root fresh (6.8 g) and dry weights (1.9 g), along with a root length of 24.8 cm. Chlorophyll content reached a maximum of 6.4 mg/g in IBA-treated cuttings. Higher IAA (0.5 µg/ml) and GA3 (13.5 µg/ml) levels were observed in treated cuttings, alongside increased peroxidase activity and reduced IAA oxidase levels. Elevated phenols (1.3 mg/g FW) and carbohydrates (41.9%) also supported rooting. The highest cutting success rate (93.7%) was observed in 1000 ppm IBA-treated 30 cm cuttings in March, demonstrating that this treatment effectively promotes rooting and shooting growth in dragon fruit. [ABSTRACT FROM AUTHOR]

AbstractThe present study aimed to investigate the effect of initial inoculum size on adventitious root growth and secondary metabolite production in Stevia rebaudiana s root cultures, using various initial inoculum sizes (0.5, 1.0, 1.5, and 2.0 g). The roots were collected from the in-vitro seed-derived plantlets and transferred to a half-strength MS medium with 0.5 mg l−1 naphthalene acetic acid (NAA) to establish adventitious root cultures. Growth kinetics and fresh and dry biomass of adventitious root cultures were enhanced with inoculum size from 0.5–2.0 g. Adventitious root cultures did not show lag phases however, the growth curve was increased at an early stage (day 3) of log phases and sustained for 27 days of culture. The fresh and dry biomass accumulations of the adventitious root cultures were increased by 51 and 120% with 1.5 g inoculum size as compared to a smaller inoculum size (0.5 g). Adventitious root cultures at an initial inoculum size of 2.0 g had a significantly higher content of total phenolics (TPC; 41.46 mg g−1 DW), total flavonoids (TFC; 33.44 mg g−1 DW), and around 98.82% higher potential for scavenging free radicals. In addition, the initial inoculum size of 1.5 g was observed with higher dulcoside contents (0.71 mg g−1 DW), and an inoculum size of 1.0 g was noted with higher content of stevioside (64.75 mg g−1 DW) and rebaudioside (29.67 mg g−1 DW). Therefore, it is concluded that adventitious root cultures accumulated greater fresh and dry biomasses at an inoculum size of 1.5 g, a higher amount of TPC, TFC, and DRSA at 2.0 g, and stevioside and rebaudioside contents at 1.0 g. [ABSTRACT FROM AUTHOR]

Feature selection is a pivotal research area within machine learning, tasked with pinpointing the essential subset of features from a broad array that critically influences a model's predictive capabilities. This process enhances model precision and drastically lowers the computational demands associated with training and predicting. Consequently, more advanced optimization techniques are employed to address the challenge of feature selection. This paper introduces an innovative intelligent optimization algorithm, the Plant Root Growth Optimization (PRGO) algorithm, inspired by the structure of plant rhizomes and the way they absorb nutrients.In the algorithm, the plant rhizomes are divided into two categories, the taproot and the fibrous root.the growth process of the taproot plants is associated with the global exploration search, and the growth process of the fibrous root plants relates to the local exploitation search.The global asymptotic convergence of the algorithm is proved by applying Markov's correlation theory, and simulation results using CEC2014 and CEC2017 test sets show that the proposed algorithm has excellent performance.Moreover, a binary variant of this algorithm (BPRGO) has been specifically crafted in this research to tackle the complexities of high-dimensional feature selection issues. The algorithm was compared to eight well-known feature selection methods and its performance was evaluated using a variety of evaluation metrics on 16 high-dimensional datasets from the Arizona State University feature selection library. and the performance of the proposed algorithm was evaluated through feature subset size, classification accuracy, fitness value, and F1-score. The experimental results show that BPRGO achieves the best performance, which has stronger feature reduction ability and achieves better overall performance on most datasets. BPRGO can obtain extremely smaller feature subsets while maintaining much higher classification accuracy, and satisfactory F1-score. [ABSTRACT FROM AUTHOR]

Non-halophytic plants are highly susceptible to salt stress, but numerous studies have shown that halo-tolerant microorganisms can alleviate this stress by producing phytohormones and enhancing nutrient availability. This study aimed to identify and evaluate native microbial communities from salt-affected regions to boost black gram (Vigna mungo) resilience against salinity, while improving plant growth, nitrogen uptake, and nodulation in saline environments. Six soil samples were collected from a salt-affected region in eastern Uttar Pradesh, revealing high electrical conductivity (EC) and pH, along with low nutrient availability. A total of 72 bacterial strains were isolated from soil and 28 from black gram (Vigna mungo) root nodules, with 32 of the soil bacteria tolerating up to 10% NaCl. These bacteria were characterized through taxonomic and biochemical tests. Cross-compatibility analysis showed two rhizobia strains were highly compatible with five salt-tolerant bacteria. These strains exhibited significant plant growth-promoting traits, including phosphate, potassium, and zinc solubilization, as well as ACC deaminase, IAA, siderophore, and EPS production. Strain Paenibacillus sp. SPR11 showed the strongest overall performance. Genetic diversity was assessed using BOX-PCR and ERIC-PCR, and strains were identified through 16S rRNA gene sequencing. In a seed germination study under saline conditions (200 mM and 300 mM), co-inoculation with Bradyrhizobium yuanmingense PR3 and Paenibacillus sp. SPR11 resulted in a significant enhancement in seed germination (40%), root growth (84.45%), and shoot growth (90.15%) compared to single inoculation of B. yuanmingense PR3. Under greenhouse conditions in Leonard jars, co-inoculation with strains PR3 and SPR11 significantly enhanced shoot and root length, fresh and dry biomass, nodule count, and nodule fresh and dry weight. Chlorophyll content, nutrient uptake, and crude protein levels increased, while proline content decreased compared to single inoculation and uninoculated seeds. Our best understanding leads us to believe that this is the very first report of utilizing co-inoculation of salt-tolerant Paenibacillus sp. SPR11 and B. yuanmingense PR3, demonstrating their promising potential to alleviate salt stress and enhance growth, root architecture, nitrogen uptake, and nodule formation in black gram under nitrogen free saline conditions. [ABSTRACT FROM AUTHOR]

Mowing significantly influences nutrient cycling and stimulates metabolic adjustments in plants to promote regrowth. Plant growth-promoting rhizobacteria (PGPR) are crucial for enhancing plant growth, nutrient absorption, and stress resilience; however, whether inoculation with PGPR after mowing can enhance plant regrowth capacity further, as well as its specific regulatory mechanisms, remains unexplored. In this study, PGPR Pantoea eucalyptus (B13) was inoculated into mowed Leymus chinensis to evaluate its effects on phenotypic traits, root nutrient contents, and hormone levels during the regrowth process and to further explore its role in the regrowth of L. chinensis after mowing. The results showed that after mowing, root nutrient and sugar contents decreased significantly, while the signal pathways related to stress hormones were activated. This indicates that after mowing, root resources tend to sacrifice a part of growth and prioritize defense. After mowing, B13 inoculation regulated the plant's internal hormone balance by reducing the levels and signal of JA, SA, and ABA and upregulated the signal transduction of growth hormones in the root, thus optimizing growth and defense in a mowing environment. Transcriptomic and metabolomic analyses indicated that B13 promoted nutrient uptake and transport in L. chinensis root, maintained hormone homeostasis, enhanced metabolic pathways related to carbohydrates, energy, and amino acid metabolism to cope with mowing stress, and promoted root growth and regeneration of shoot. This study reveals the regenerative strategy regulated by B13 in perennial forage grasses, helping optimize resource utilization, increase yield, and enhance grassland stability and resilience. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vegetal‐derived protein hydrolysates (PHs) have been recognized as sustainable biostimulant products due to their beneficial effects on crops. However, most studies on PHs have been conducted at a fixed ratio of nitrate‐to‐ammonium (NO3−:NH4+) without considering other N application scenarios, leading to inconsistent results among the studies. This study compared the influences of N levels (2 or 10 mM N), NO3:NH4 ratios (100:0, 75:25, 50:50, or 25:75), and PH application methods – control, foliar spray (PH‐F) or root application (PH‐R) – on the yield, morphology, nutrients, and nutraceutical quality of hydroponic lettuce. RESULTS: Nitrogen level, NO3:NH4 ratio, and PH application affected plant growth, morphology, and quality significantly, highlighting the importance of the interactions among these factors. Shoot growth was influenced by NO3:NH4 ratios, PH, and their interactions. Similar trends were observed in chlorophyll content. The interactions among all three factors significantly influenced root growth and morphology. Root application (PH‐R) protected lettuce from yield loss caused by low NO3:NH4 ratios and from reduced antioxidant compounds caused by high N levels. Vegetal‐derived protein hydrolysates improved nutrient uptake through two‐way and three‐way interactions although neither PH nor any interactions affected nitrate concentrations. CONCLUSION: This study demonstrated that PH interacts with N level and NO3:NH4 ratio, affecting hydroponic lettuce yield and quality. In particular, the root application of PH was the most effective method for enhancing yield (shoot fresh weight), quality (chlorophylls, carotenoids, flavonoids, and phenols), and nutrient uptake in hydroponically grown lettuce in relation to N form and level. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: We investigate the impact of a 20‐yr irrigation on root water uptake (RWU) and drought stress release in a naturally dry Scots pine forest.We use a combination of electrical resistivity tomography to image RWU, drone flights to image the crown stress and sensors to monitor soil water content.Our findings suggest that increased water availability enhances root growth and resource use efficiency, potentially increasing trees' resistance to future drought conditions by enabling water uptake from deeper soil layers.This research highlights the significant role of ecological memory and legacy effects in determining tree responses to environmental changes. [ABSTRACT FROM AUTHOR]

Planting aluminum-tolerant legume green manure is a cost-effective and sustainable method to increase soil fertility as well as decrease Al toxicity in acidic soils. By analyzing the relative root elongation of seven legume green manure species, common vetch (Vicia sativa L.) was identified as an Al-resistant species. Furthermore, cultivars 418 (cv. Sujian No.3) and 426 (cv. Lanjian No.3) were identified as Al-resistant and -sensitive cultivars, respectively, among 12 common vetch germplasms. The root growth of 418 was less inhibited by Al toxicity in both the germination stage and seedling stage than that of 426. Under Al toxicity, 418 accumulated less Al in both roots and shoots. Citrate is more abundant in the roots of common vetch compared to oxalate or malate. The internal citrate contents showed no significant difference between 418 and 426 under either control or Al treatment. However, the citrate efflux increased in response to Al in 418 but not in 426 and was higher in 418 under Al stress than in 426. Consistently, VsMATE1 expression increased faster and to a greater extent in 418 than 426 in response to Al stress. These results indicated that a VsMATE1-mediated citrate efflux might play an important role in Al resistance in common vetch. It is suggested that VsMATE1 is a valuable candidate gene for aluminum resistance breeding. [ABSTRACT FROM AUTHOR]

Intercropping with legume forages is recognized as an effective strategy for enhancing nitrogen levels in agroforestry, while mowing may influence nitrogen fixation capacity and yield. This study investigated the rooting, nitrogen fixation, nutritive value, and yield of alfalfa (Medicago sativa L.) under intercropping and varying mowing frequencies (CK, 2, and 3) from 2021 to 2023, using walnut (Juglans regia L.) and alfalfa as experimental subjects. The results indicated that intercropping suppressed root growth, whereas increased mowing frequency stimulated root development in the topsoil (0–20 cm). Specifically, the average root length density, root surface area, and root volume from the twice- and thrice-mowed treatments increased by 18.26, 17.45, and 4.15%, respectively, in comparison to the control. The δ15N values of the intercropped alfalfa were significantly lower than those of the monocropped alfalfa (p < 0.05), with the δ15N values of the mowing-thrice treatment increasing by an average of 38.61% compared to the control. Intercropping suppressed alfalfa yield but did not affect the total nitrogen content in the leaves or the nutritive value, and all mowing treatments resulted in land equivalent ratios (LERs) greater than 1. Furthermore, increased mowing frequency enhanced both the nutritive value and yield of alfalfa. Our study suggests that intercropping with walnut can improve biological nitrogen fixation in alfalfa, and that adopting a mowing-thrice regime can optimize yield and nutritive value. [ABSTRACT FROM AUTHOR]

Roots play essential roles in the acquisition of water and minerals from soils in higher plants. However, water or nutrient limitation can alter plant root morphology. To clarify the spatial distribution characteristics of essential nutrients in citrus roots and the influence mechanism of micronutrient deficiency on citrus root morphology and architecture, especially the effects on lateral root (LR) growth and development, two commonly used citrus rootstocks, trifoliate orange (Poncirus trifoliata L. Raf., Ptr) and red tangerine (Citrus reticulata Blanco, Cre), were employed here. The analysis of the mineral nutrient distribution characteristics in different root parts showed that, except for the P concentrations in Ptr, the last two LR levels (second and third LRs) had the highest macronutrient concentrations. All micronutrient concentrations in the second and third LRs of Ptr were higher than those of Cre, except for the Zn concentration in the second LR, which indicates that Ptr requires more micronutrients to maintain normal root system growth and development. Principal component analysis (PCA) showed that B and P were very close in terms of spatial distribution and that Mo, Mn, Cu, and Fe contributed significantly to PC1, while B, Cu, Mo, and Zn contributed significantly to PC2 in both rootstocks. These results suggest that micronutrients are major factors in citrus root growth and development. The analysis of root morphology under micronutrient deficiency showed that root growth was more significantly inhibited in Ptr and Cre under Fe deficiency (FeD) than under other micronutrient deficiencies, while Cre roots exhibited better performance than Ptr roots. From the perspective of micronutrient deficiency, FeD and B deficiency (BD) inhibited all root morphological traits in Ptr and Cre except the average root diameter, while Mn deficiency (MnD) and Zn deficiency (ZnD) had lesser impacts, as well as the morphology of the stem. The mineral nutrient concentrations in Ptr and Cre seedlings under micronutrient deficiency revealed that single micronutrient deficiencies affected both their own concentrations and the concentrations of other mineral nutrients, whether in the roots or in stems and leaves. Dynamic analysis of LR development revealed that there were no significant decreases in either the first or second LR number in Ptr seedlings under BD and ZnD stress. Moreover, the growth rates of first and second LRs in Ptr and Cre did not significantly decrease compared with the control under short-term (10 days) BD stress. Altogether, these results indicate that micronutrients play essential roles in citrus root growth and development. Moreover, citrus alters its root morphology and biological traits as a nutrient acquisition strategy to maintain maximal micronutrient acquisition and growth. The present work on the spatial distribution characteristics and micronutrient deficiency of citrus roots provides a theoretical basis for effective micronutrient fertilization and the diagnosis of micronutrient deficiency in citrus. [ABSTRACT FROM AUTHOR]

Heat stress is one of the major concerns for wheat production worldwide. Morphological parameters such as germination, leaf area, shoot, and root growth are affected by heat stress, with affected physiological parameters including photosynthesis, respiration, and water relation. Heat stress also leads to the generation of reactive oxygen species that disrupt the membrane systems of thylakoids, chloroplasts, and the plasma membrane. The deactivation of the photosystems, reduction in photosynthesis, and inactivation of Rubisco affect the production of photo-assimilates and their allocation, consequently resulting in reduced grain yield and quality. The development of thermo-tolerant wheat varieties is the most efficient and fundamental approach for coping with global warming. This review provides a comprehensive overview of various aspects related to heat stress tolerance in wheat, including damages caused by heat stress, mechanisms of heat stress tolerance, genes or QTLs regulating heat stress tolerance, and the methodologies of breeding wheat cultivars with high heat stress tolerance. Such insights are essential for developing thermo-tolerant wheat cultivars with high yield potential in response to an increasingly warmer environment. [ABSTRACT FROM AUTHOR]

Cyclic nucleotide-gated channel 5 (CNGC5), CNGC6, and CNGC9 (CNGC5/6/9 for simplicity) control Arabidopsis root hair (RH) growth by mediating the influx of external Ca2+ to establish and maintain a sharp cytosolic Ca2+ gradient at RH tips. However, the underlying mechanisms for the regulation of CNGCs remain unknown. We report here that calcium dependent protein kinase 1 (CPK1) directly activates CNGC5/6/9 to promote Arabidopsis RH growth. The loss-of-function mutants cpk1-1, cpk1-2, cngc5-1 cngc6-2 cngc9-1 (shrh1/short root hair 1), and cpk1 shrh1 show similar RH phenotypes, including shorter RHs, more RH branching, and dramatically attenuated cytosolic Ca2+ gradients at RH tips. The main CPK1-target sites are identified as Ser20, Ser27, and Ser26 for CNGC5/6/9, respectively, and the corresponding alanine substitution mutants fail to rescue RH growth in shrh1 and cpk1-1, while phospho-mimic versions restore the cytosolic Ca2+ gradient at RH apex and rescue the RH phenotypes in the same Arabidopsis mutants. Thus we discover the CPK1-CNGC modules essential for the Ca2+ signaling regulation and RH growth in Arabidopsis. Cyclic nucleotide-gated channels (CNGCs) contribute to root hair growth through mediating Ca2+ influx at root hair tips. Here calcium dependent protein kinase 1 is found to directly activate CNGCs via phosphorylation and promote root hair growth in Arabidopsis. [ABSTRACT FROM AUTHOR]

Plants encounter various abiotic stresses throughout growth and development, with aluminum stress emerging as a major global agricultural challenge that hinders plant growth and limits crop yields in acidic soils. In this study, nanomaterials with dual functions, controlled release and adsorption, were constructed to alleviate aluminum toxicity. Specifically, two metal-organic frameworks, UiO-66 and ZIF-8, were used to load naphthylacetic acid and tryptophan, respectively. These two controlled-release systems were then combined with a chitosan-based matrix (NT@CS@UZ) to enable the regulated release of both compounds at distinct rates. Concurrently, the porous structure of these materials facilitates the adsorption of soluble aluminum in the plant rhizosphere. Results show that the acidic environment accelerates ZIF-8 degradation, triggering an early release of tryptophan under aluminum stress conditions. This early release promotes plant growth and alleviates stress damage. Naphthylacetic acid is subsequently released at a slower, sustained rate to stimulate root growth and further mitigate aluminum toxicity in roots. Additionally, NT@CS@UZ effectively adsorbs aluminum ions, limiting Al3+ uptake by plants and creating a low-aluminum barrier to protect roots. These dual function nanomaterials significantly boost crop yield and enhance stress resilience, presenting new avenues for food security and sustainable agricultural practices. [Display omitted] • The integrated system addresses the long-standing acid aluminum toxicity. • The integrated system is synthesized into beads and sponges to enhance operability. • The integrated system regulates the release of naphthylacetic acid and tryptophan. • The integrated system can adsorb Al3+ to alleviate aluminum stress. [ABSTRACT FROM AUTHOR]

Hard pans, soil compaction, soil aggregation, and stones create physical barriers that can affect the development of a root system. Roots are known to exploit paths of least resistance to avoid such obstacles, but the mechanism through which this is achieved is not well understood. Here, we used a combination of 3D-printed substrates with a high-throughput live-imaging platform to study the responses of maize roots to a range of physical barriers. Using image analysis algorithms, we determined the properties of growth trajectories and identified how the presence of rigid circular obstacles affects the ability of a primary root to maintain its vertical trajectory. The results showed that the types of growth responses were limited, with both vertical and oblique trajectories being found to be stable and influenced by the size of the obstacles. When obstacles were of intermediate sizes, trajectories were unstable and changed in nature through time. We formalized the conditions required for root trajectory to change from vertical to oblique, linking the angle at which the root detaches from the obstacle to the root curvature due to gravitropism. Exploitation of paths of least resistance by a root might therefore be constrained by the ability of the root to curve and respond to gravitropic signals. [ABSTRACT FROM AUTHOR]

Rhizospheric pH, an important environmental cue, severely impacts plant growth and fitness, therefore, has emerged as a major determinant of crop productivity. Despite numerous attempts, the key questions related to plants response against rhizospheric pH remains largely elusive. The present study provides a mechanistic framework for rhizospheric pH‐mediated root growth inhibition (RGI). Utilizing various genetic resources combined with pharmacological agents and high‐resolution confocal microscopy, the study provides direct evidence for the involvement of jasmonates and auxin in rhizospheric pH‐mediated RGI. We show that auxin maxima at root tip is tightly regulated by the rhizospheric pH. In contrast, jasmonates (JAs) abundance inversely correlates with rhizospheric pH. Furthermore, JA‐mediated regulation of auxin maxima through GRETCHEN HAGEN 3 (GH3) family genes explains the pattern of RGI observed over the range of rhizospheric pH. Our findings revealed auxin as the key regulator of RGI during severe pH conditions, while JAs antagonistically regulate auxin response against rhizospheric pH. Summary statement: The current study identifies the mechanistic framework of rhizospheric pH‐mediated root growth inhibition in model plant Arabidopsis through a prominent crosstalk between two phytohormones, that is, auxin and jasmonates. [ABSTRACT FROM AUTHOR]

Changes in root system architecture are vital for plant adaptation to drought stress, yet the underlying molecular mechanisms of this process remain largely elusive. Here, FUSCA3 (FUS3), a B3 domain transcription factor isolated from Populus euphratica, was found to be an important gene of regulating lateral root (LR) development under drought stress. The expression of PeFUS3 was strongly induced by ABA and dehydration treatments. Overexpressing PeFUS3 in poplar 84 K (P. alba × P. glandulosa) positively regulated LR growth and enhanced drought tolerance, while the knockout lines, generated by the CRISPR/Cas9 system, displayed repressed LR growth and weakened drought tolerance. Further investigation demonstrated that PeFUS3 activated the expression of PIN2, PIN6a and AUX1, which were key genes involved in auxin transport, suggesting PeFUS3 modulated LR development under drought stress through auxin signalling. Moreover, PeFUS3 directly upregulated PePYL3 expression, and overexpressing PePYL3 poplar lines exhibited significantly increased drought resistance. In addition, PeABF2, an ABA responsive transcription factor, interacted with PeFUS3 and activated its transcription, indicating PeFUS3 was involved in ABA signalling pathway. Taken together, PeFUS3 is a key regulator, maintaining root growth of poplar by modulating the crosstalk of auxin and ABA signalling under drought stress. Summary statement: PeFUS3, a B3 domain transcription factor, promotes lateral root (LR) development under drought stress via modulating the crosstalk of auxin and ABA signalling. These findings unravel a novel molecular mechanism of balancing root growth and drought resistance under drought stress in Populus. [ABSTRACT FROM AUTHOR]

Posttranslational tyrosine sulfation of peptides and proteins is catalysed by tyrosylprotein sulfotransferases (TPSTs). In Arabidopsis, tyrosine sulfation is essential for the activities of peptide hormones, such as phytosulfokine (PSK) and root meristem growth factor (RGF). Here, we identified a TPST‐encoding gene, MtTPST, from model legume Medicago truncatula. MtTPST expression was detected in all organs, with the highest level in root nodules. A promoter:GUS assay revealed that MtTPST was highly expressed in the root apical meristem, nodule primordium and nodule apical meristem. The loss‐of‐function mutant mttpst exhibited a stunted phenotype with short roots and reduced nodule number and size. Application of both of the sulfated peptides PSK and RGF3 partially restored the defective root length of mttpst. The reduction in symbiotic nodulation in mttpst was partially recovered by treatment with sulfated PSK peptide. MtTPST‐PSK module functions downstream of the Nod factor signalling to promote nodule initiation via regulating accumulation and/or signalling of cytokinin and auxin. Additionally, the small‐nodule phenotype of mttpst, which resulted from decreased apical meristematic activity, was partially complemented by sulfated RGF3 treatment. Together, these results demonstrate that MtTPST, through its substrates PSK, RGF3 and other sulfated peptide(s), positively regulates nodule development and root growth. Summary statement: We identified and characterized a tyrosylprotein sulfotransferase‐encoding gene, MtTPST, from model legume Medicago truncatula.Through mutant analysis and sulfated peptide treatment, we revealed that MtTPST positively regulates nodule development and root growth via sulfation of PSK and RGF peptides. [ABSTRACT FROM AUTHOR]

Drought is an important abiotic factor constricting crop production globally. Although the roles of JAZ proteins in regulating jasmonic acid signalling and plant responses to environmental stress are well documented, their specific functions and underlying mechanisms remain little known. In this study, JAZ proteins in barley were thoroughly analyzed, revealing a total of 11 members classified into three phylogenetic subgroups. HvJAZ2, based on its distinct expression patterns, is considered a key candidate gene for regulating drought tolerance in barley. Using the HvJAZ2 knockout mutants, we revealed that the gene negatively regulates drought tolerance by inhibiting barley root growth. Notably, the jaz2 mutants upregulated the expression of root development genes, including SHR1, PLT1, PLT2 and PLT6. plt2 and plt1/plt2 mutants exhibited suppressed root development and reduced drought tolerance. Analysis of interactions between HvJAZ2 and other proteins showed that HvJAZ2 does not directly interact with HvPLT1/2/6, but interacts with some other proteins. BIFC and LCA assays further confirmed the nuclear interaction between HvJAZ2 and HvMYC2. Y1H and Dual‐Luciferase experiments demonstrated that HvMYC2 can bind to and activate the HvPLT2 promoter. In summary, HvJAZ2 negatively regulates root development and drought tolerance in barley by suppressing HvPLT2 expression through interacting with HvMYC2. Summary statement: Drought is a major abiotic factor limiting crop production globally.This study found HvJAZ2 negatively regulates drought tolerance in barley (Hordeum vulgare L.) by suppressing HvPLT2 expression through interacting with HvMYC2, which is potentially useful for improving barley's drought tolerance. [ABSTRACT FROM AUTHOR]