Environmental and Experimental Botany

Salinity is a major abiotic stress that severely limits plant growth and productivity, causing substantial yield losses. Despite barleys relative tolerance to salinity, the underlying physiological and molecular mechanisms remain incompletely understood. In this study, we employed an integrative approach combining agronomic, physiological, biochemical, and transcriptomic analyses to investigate salinity responses in the spring barley cultivar Giza 134 under both field and lysimeter-based conditions. Salinity stress significantly reduced growth and yield-related traits, with more pronounced effects observed under lysimeter-imposed salinity, reflecting higher stress intensity. These reductions were associated with impaired water status, altered leaf structural traits, and declines in photosynthetic pigment content. In contrast, proline accumulation increased, indicating activation of osmotic adjustment mechanisms. Salinity also disrupted ionic homeostasis, as evidenced by elevated Na+ levels, reduced K+ content, and an increased Na+/K+ ratio. Enhanced lipid peroxidation and elevated catalase and peroxidase activities suggested increased oxidative stress and activation of antioxidant defenses. Transcriptome profiling identified 4,298 differentially expressed genes, including 1,764 upregulated and 2,534 downregulated genes. Functional enrichment analyses revealed upregulation of pathways related to stress adaptation, redox regulation, and metabolic reprogramming, while genes associated with photosynthesis, ribosome biogenesis, and protein synthesis were strongly suppressed. Several novel stress-responsive genes involved in signaling, osmoprotection, antioxidant defense, and central metabolism were highly induced, supported by coordinated enrichment of cis-regulatory motifs in their promoter regions. Together, these findings provide a comprehensive physiological and molecular framework for salinity tolerance in Giza 134 and highlight candidate genes and pathways for breeding salt-resilient cultivars suited to saline-prone environments.

Rice (Oryza sativa) is highly sensitive to salinity, yet the metabolic mechanisms underlying salt tolerance remains incompletely understood. In this study, we performed leaf tissue-specific untargeted metabolomic profiling of the salt-tolerant introgression line JN100 (JN), its donor parent Nona Bokra (NB), and its recurrent parent Jupiter (JU) to characterize metabolic responses to salt stress. Comparative analysis identified differentially accumulated metabolites (DAMs) spanning diverse chemical classes, including amino acids, sugars and carbohydrates, lipids, organic acids, cofactors, electron carriers, and nucleotides. Under salt stress (SS), 201 DAMs (89 upregulated and 112 downregulated) were detected in JN relative to JU. Notably, metabolites such as allantoin, glycitin, nicotinamide ribotide, D-arabinono-1,4-lactone, violanthin, L-methionine S-oxide, ribitol, lysine, rutin, glutamine, pantothenic acid, and quinic acid, showed significant differential accumulation. Pathway enrichment analysis revealed significant enrichment of arginine biosynthesis, purine metabolism, and alanine, aspartate, and glutamate metabolism, indicating extensive reprogramming of nitrogen and energy-associated metabolic pathways under salinity stress. Integration of transcriptomic and metabolomic datasets from the SS experiments further identified ten differentially expressed genes (DEGs) associated with the metabolite network in the JN vs. JU comparison. Among these, OsDHQDT/SDH, OsFd-GOGAT, phenylalanyl-tRNA synthetase, OsP5CS1, OsP5CS2, and a pyridoxal phosphate-dependent transferase were linked to metabolites involved in shikimate, amino acid, and proline metabolism. Collectively, these results demonstrate that salinity tolerance in rice is associated with coordinated transcriptional and metabolic reprogramming that supports oxidative stress mitigation and adaptive stress responses.

Several tomato (Solanum lycopersicum) varieties are sensitive to heat stress, which compromises plant growth, development, and ultimately yield. Biostimulants represent a promising approach to improve crop performance, yet their widespread adoption is hindered by the incomplete understanding of their mechanisms of action. This study aimed to elucidate the physiological and molecular effects of a protein hydrolysate-based biostimulant (Leafamine(R)), in tomato, under both optimal and heat stress conditions. Leafamine(R) increased primary root length by 15 to 20% compared to the controls, independent of the tested conditions, through promotion of cell division and potentially expansion. Transcriptomic analyses revealed the upregulation of genes involved in cell division and expansion under both optimal and heat stress conditions and the downregulation of heat stress markers under heat stress conditions. Hormone and metabolite profiling showed elevated levels of jasmonic and salicylic acid, putrescine, citrulline, and GABA, after Leafamine(R) treatment, consistent with the activation of stress tolerance pathways. Leafamine(R) pre-treated seedlings exhibited reduced growth inhibition during heat exposure, suggesting a priming effect. These findings highlight Leafamine(R) as a promising biostimulant for enhancing tomato growth in the context of climate change and the potential of biostimulants generically.

Stomata are the pores on plant surface, and these tiny pores are responsible for the flow of gas between plants and atmosphere. Currently, what effects of the broad and continuous increase in stomatal density achieved via genetic engineering on plant growth and development remain poorly understood. The 9 Arabidopsis transgenic lines with increased stomatal density were acquired through overexpressing FSTOMAGEN (the homologs of STOMAGEN, which are in Flaveria). The intermediate stomatal density (SD) lines exhibited increased trend in biomass. Compared with the lines with low SD, the biomass of Arabidopsis lines with intermediate SD (484 mm-2) significantly increased. There was a positive and significant correlation between biomass and relative water content. Across these transgenic lines, only during the earlier phase of growth, the leaf area exhibited a gradually increased trend as stomatal density increased, and there was both a significant linear relationship between SD and leaf growth rate and a strong linear relationship between SD and leaf area. In contrast, a clear relationship during the later phase wasnt observed. Under lower growth light intensity, there was an increased trend of biomass from other lines to the lines with intermediate SD, and the photosynthetic rate and stomatal conductance of the intermediate line were significantly increased. This study reveals plant-growth alterations that correspond to broad and near-continuous increases in stomatal density achieved via genetic engineering. Our study sheds light on the prerequisites for elevated stomatal density achieved via genetic engineering to promote plant growth.

O_LIC4 photosynthesis and the crassulacean acid metabolism (CAM) rarely co-evolved in a single lineage, but Portulaca can switch from C4 to CAM under drought stress. Little is known about CAM responses to nutrient availability, hence the goal of this work was to assess the influence of macronutrients over C4-CAM. C_LIO_LIP. oleracea was grown hydroponically and subjected to treatments (+/- PEG) for: nitrate deficiency (-NO3-), ammonium (NH4+), NO3- + NH4+, magnesium (-Mg), phosphorus (-P), calcium (-Ca), potassium (-K), and sulphur (-S) deficiencies, and salt stress. Samples were monitored for diurnal titratable acidity ({Delta}H+), osmotic potential, and gene relative expression for core C4/CAM and signaling genes. C_LIO_LI-NO3- induced CAM even without PEG, a process probably without the mediation of abscisic acid (ABA). Notably, -P showed a trend to induce CAM without PEG and -Ca prevented CAM induction even with PEG. Salt stress induced CAM, and NH4+ was not toxic for P. oleracea. Other treatments showed less conspicuous responses. C_LIO_LIThis work brings an unprecedented overview of the nutrition of C4 and CAM, suggesting perspectives for deepening the study of C4-CAM. Understanding the molecular mechanisms and environmental signaling of C4-CAM is essential for realizing the evolution of two CCMs in a single plant. C_LI

BackgroundSorbus sibirica Dong Hong is a promising ornamental cultivar, but its optimal light conditions remain unclear. AimsThis study evaluated the effects of shading on seedling growth, physiology, root morphology, and leaf surface micromorphology. MethodsOne-year-old seedlings were grown under full sunlight (CK) and 30%, 50%, or 70% shade for 100 days. Growth, biomass, root traits, chlorophyll, invertase, soluble protein, stomatal characteristics, and epicuticular wax morphology were determined. ResultsShading significantly affected all measured traits. The 30% shade treatment produced the greatest seedling height, which increased by 118.18% compared with CK, and the highest chlorophyll content, which increased by 120.21%. Soluble protein content was slightly increased, whereas invertase activity decreased under moderate shading. Although total biomass decreased by 18.63%, root development remained relatively stable under 30% shade, with slight increases in total root length and average root diameter. Stomatal density was highest under this treatment, and the epicuticular wax structure remained relatively regular. In contrast, 70% shade markedly inhibited biomass accumulation and root development. ConclusionsModerate shading, particularly 30%, provided the most favorable light environment for Sorbus sibirica Dong Hong seedlings and is recommended for summer nursery cultivation in Northeast China.

Concurrent exposure to heat and drought stress compromises legume productivity, yet their combined effects are rarely quantified systematically. We compiled a database of 18 studies covering seven legume species. From these, we extracted 929 physiological, biochemical, and yield-related traits and calculated actual-to-additive ratios to classify heat-drought interactions as antagonistic (ratio < 1), additive (ratio = 1), or synergistic (ratio > 1). Additive heat-drought relationships accounted for 59 % of all classifiable observations, 37% relationships were antagonistic, and 4% synergistic. The relationship varied with species, genotype, trait, and experimental conditions highlighting the complexity of combined abiotic stress effects. The results challenge the common assumption that concurrent stresses invariably exacerbate damage and underscore the need for more realistic, quantitatively defined stress treatments as well as frameworks that integrate trait-level responses into predictive models of crop growth and development. Our synthesis provides a quantitative foundation to understand legume phenotypes under the increasingly frequent co-occurrence of heat and drought stress and identifies research areas where further work is needed to improve insight into combined stress responses. HighlightsO_LICombined heat and drought responses were mainly additive or antagonistic. C_LIO_LIEvidence is biased toward few legumes and controlled environments. C_LIO_LIField-based, multi-species studies are needed to identify adaptive traits. C_LI

Drought is a major abiotic stress threatening plant productivity and agricultural sustainability, yet the molecular mechanisms underlying adaptive root responses to water deficit in the water use strategies continuum remain insufficiently understood, particularly in perennial crops. In this study, we explored drought responses in nine accessions belonging to three wild Vitis species (V. acerifolia, V. candicans, and V. doaniana) displaying varying drought-response strategies. Plants were subjected to moderate drought stress (40% soil water content) for three weeks under greenhouse conditions. By integrating physiological, metabolic, and transcriptomic analyses, we aimed to identify both conserved and species-specific mechanisms associated with drought adaptation. Differential expression analyses revealed a conserved core set of drought-responsive genes shared among species, including genes involved in abscisic acid signaling, reactive oxygen species detoxification, solute transport, and plant defense. In parallel, each species exhibited distinct transcriptional and metabolic signatures reflecting alternative adaptive strategies related to osmoregulation, and oxidative stress mitigation. Weighted gene co-expression network analysis (WGCNA) further revealed significant associations between constitutive, non-plastic gene expression and root phenotypic traits. Overall, our findings demonstrate that wild Vitis species rely on both conserved stress-responsive pathways and species-specific constitutive regulation to cope with drought stress. These results highlight the importance of root-associated traits and intrinsic regulatory networks in shaping drought adaptation and provide new targets for the development of drought-resilient grapevine rootstocks.

Chickpea (Cicer arietinum) is a globally important legume crop whose productivity is frequently constrained by terminal drought, particularly in rainfed systems. We used high-throughput phenotyping of 35 diverse chickpea haplotypes at contrasting watering regimes (80% and 40% field capacity) to identify superior haplotypes. Significant haplotype:watering interactions were observed for water-use dynamics, growth rates, biomass accumulation and nodulation, indicating strong genetic control over drought responses. Certain haplotypes (e.g., ICC2210 and ICC18839) maintained relatively high water-use efficiency and growth under stress, while others exhibited pronounced reductions in biomass and nodulation. Principal Component Analyses (PCA) were used to identify haplotypes associated with tolerant and sensitive stress phenotypes. Metabolomic profiling revealed widespread reprogramming of metabolism under water limitation, with 57 of 82 metabolites significantly affected by treatment. A consistent decrease in tricarboxylic acid intermediates, including succinic acid, indicated altered energy metabolism, while accumulation of osmoprotectants such as proline and sucrose reflected adaptive responses to osmotic stress. Multivariate and ANOVA Simultaneous Component Analyses (ASCA) identified key metabolites as major contributors to haplotype-specific drought responses. These metabolites are linked to nitrogen metabolism, stress signalling and cellular protection mechanisms. These results demonstrate substantial variation in drought adaptation among chickpea haplotypes and confirm that the integration of phenotypic and metabolomic traits is a powerful approach to identify drought-resilient genotypes.

Heat stress is one of the most damaging abiotic constraints on crop productivity, and its consequences are expected to intensify as extreme temperature events become more frequent and severe. Pepper (Capsicum annuum L.) is particularly vulnerable to sustained high temperatures, which can disrupt photosynthetic performance, cellular homeostasis, and redox regulation. However, the physiological and transcriptional dynamics underlying genotype-dependent responses to prolonged heat exposure remain insufficiently understood. We combined repeated physiological measurements with time-course RNA sequencing to compare GPC003240, previously identified as a candidate heat-tolerant accession, with two non-elite accessions, GPC010350 and GPC014930, which are phenotypically divergent from each other, under 40/30 {degrees}C Day/night temperatures for up to six days. GPC010350 maintained comparatively stable photosystem II performance and higher stomatal conductance, whereas GPC014930 showed progressive photochemical impairment and lower conductance; GPC003240 displayed a distinct, moderately responsive profile. Transcriptomic responses showed partial functional convergence during the early phase of stress exposure but diverged markedly after six days. When gene expression at day 6 was compared with the pre-treatment baseline separately within each genotype, 4,436 differentially expressed genes were detected in GPC010350, compared with 680 in GPC003240 and only 78 in GPC014930. The late response of GPC010350 was associated with enrichment of RNA- and ribosome-related, biosynthetic, DNA-repair, and genome-maintenance functions. By contrast, GPC014930 showed negative enrichment of photosynthesis, plastid organization, redox homeostasis, and translation-related processes. Global co-expression analysis identified a time-decreasing photosynthesis-associated module (ME5) and two time-increasing modules, ME12 and ME19, that were enriched in genes contributing to the late GPC010350 response. Integration of differential expressions, module membership, and functional annotation highlighted a heat shock transcription factor (Caz03g27980), HSP101 (Caz03g07770), and a dual-specificity phosphatase (Caz05g20970) as candidates for further investigation. Overall, the results suggest that genotype-dependent responses to prolonged heat exposure were associated not only with the magnitude of early transcriptional change, but also with differences in the temporal organization of stress-response, maintenance, and metabolic processes. The contrasting responses of the non-elite accessions GPC010350 and GPC014930 further highlight the value of phenotypically diverse germplasm for uncovering mechanisms relevant to future heat-tolerance breeding.

Water deficit is ubiquitous in maize (Zea mays L.) cropping systems worldwide. Ethylene insensitivity in maize has been implicated in improving kernel set and yield under drought, and ARGOS genes modulate ethylene signal transduction by reducing ethylene sensitivity. Given the strong water sensitivity of silk elongation, ARGOS8 overexpression is expected to alter silk growth responses to drought. Experiments were conducted under controlled and field conditions to test the effect of ARGOS8 gene overexpression on silk growth under water deficit. Silk lengths and water use were continuously monitored, and silk elongation rate (SER) response to the fraction of transpirable soil water (FTSW) was evaluated. Silk emergence dynamics were measured in the field by daily counting the silks under contrasting water regimes. ARGOS8 transgenics maintained SER at lower FTSW than controls; however, responses varied among hybrids. Higher SER under water stress translated into a faster silk exertion rate in ARGOS8 transgenics than controls (45 vs. 25 silks d-1), leading to a greater number of exerted silks at three days post-silking (424 vs. 377, [~]90% vs. 84% of total silks, p < 0.01). Together, these results help clarify the mechanism underlying the ectopically expressed ARGOS8 effect on maize yield improvement under water stress. HighlightARGOS8 transgenic expression sustains silk elongation rates and increases silk emergence under water deficit, improving the reproductive performance of maize in water-limited environments.

The availability of pangenome and resequencing of wheat collections have facilitated the discovery of gene-trait associations in wheat. Yellow stripe-like (YSL) proteins play a key role in the uptake and translocation of metals and yet have not been fully identified and analyzed at the genome-wide level in wheat. In this study, 26 TaYSL genes were identified and divided into four distinct clades, each clade sharing similar domains and motif compositions. Most genes were upregulated under iron deficiency, whereas homoeologs of TaYSL1 were downregulated. Both SNP-based and haplotype-based association studies were used to dissect the role of TaYSLs underpinning grain iron contents (GFeC) and zinc contents (GZnC) in wheat. TaYSL6-2B and TaYSL16-1A haplotypes showed strong association with GFeC, and TaYSL14-6A showed strong association with GZnC in multiple field trials. The distribution of favorable haplotypes in global wheat collection of [~]3000 accessions showed that majority of haplotypes were more prevalent in landraces and winter wheat compared to modern cultivars and spring types, indicating their potential for use in breeding. The combination of favorable haplotypes of three YSL genes associated with GFeC and GZnC were very rare, and most of the wheat accessions has single or double favorable haplotypes. These findings provide the first comprehensive characterization of the TaYSL gene family in wheat and identify significant SNPs and elite haplotypes that can be utilized for genetic improvement and biofortification.

Plant root cellular architecture and cell wall composition influence plant productivity, stress resilience, biotic interactions, and potentially soil carbon accumulation. This study establishes comprehensive compositional parameters for roots of a lowland switchgrass genotype, DVR3. Root traits were analyzed in 12.5 cm depth segments, from Zone 1 near the surface to Zone 4 down to 50 cm. Mean abundance ({micro}g/mg) for major cell wall components included cellulose 470 {+/-} 20, xylose 250 {+/-} 20, lignin 170 {+/-} 15, and total suberin 35 {+/-} 5. Composition and cellular anatomy varied with depth, in a partially coordinated manner. Cross sections showed extensive aerenchyma in mature root regions despite greater root mass density, corresponding to abundant lignin and cellulose. Deep roots were enriched for pectin-associated traits, including arabinogalactan II, homogalacturonan, and arabinose-associated linkages. Suberin content did not vary significantly, though Casparian strip formation, endoderm and exoderm thickening, and suberin surface staining progressed with development. Similar trends in root lignin and specific root length were observed for another lowland switchgrass genotype, AP13. These results suggest that it may be possible to genetically enhance native switchgrass root chemistry to promote soil penetration and below-ground carbon accumulation by reducing variability with development, potentially via cell-type specific adjustments. HighlightOlder, shallower switchgrass crown roots are enriched in lignin and cellulose, and deeper, younger roots are pectin-rich with juvenile cellular anatomy. A more uniform compositional distribution might enhance below-ground traits. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/744798v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@159de98org.highwire.dtl.DTLVardef@124d714org.highwire.dtl.DTLVardef@1a49c14org.highwire.dtl.DTLVardef@2fa67_HPS_FORMAT_FIGEXP M_FIG C_FIG Schematic summary of switchgrass root anatomy and composition across four 12.5-cm depth zones of a 50-cm root system. Zone 1 represents older, shallow roots and Zone 4 includes younger roots and root tips. Representative cross-sections show greater aerenchyma development in older roots than in young root tips. The compositional heatmap shows higher cellulose, lignin, and xylose in Zone 1, higher pectin and nitrogen in Zone 4, and relatively little variation in suberin across zones.

Utricularia gibba L. is an aquatic carnivorous plant with a diverse set of capabilities. Reddening of traps frequently occurs in old in vitro cultures. While anthocyanins are often responsible for red coloration in plants, not every plant turns red. Stress factors like high light or excess sucrose have previously been shown to induce the formation of anthocyanins. Here, we hypothesized the red trap formation to be dependent on nutrient deprivation and tested nitrogen deprivation. The results suggest, that only in combination with light, nitrogen deficiency leads to the activation of the complete anthocyanin biosynthesis pathway and visible red coloration. However, in darkness, anthocyanin biosynthesis appears generally less active compared to light conditions and expression of most anthocyanin biosynthesis genes is not significantly upregulated under nitrogen deficiency.

Salinity stress affects rice productivity due to reduced growth and sodium ion toxicity. Previously, we identified a splice variant of RADIATION SENSITIVE23a (RAD23a) as the potential basis for variation in salt-tolerance in rice germplasm. RAD23 is a known moonlighting protein associated with protein degradation. To validate the role of RAD23a in salt stress response, we characterized gene edited mutant lines that targeted the UBL and UBA2 domains of this protein. Mutation in either domain promoted shoot growth under saline and control conditions. The mutants also differed from wildtype plants in Na and K accumulation in roots and shoots under salt stress. Transcriptome analysis of mutants versus wildtype showed differential transcript abundance of multiple inorganic phosphate (Pi) starvation related genes, including OsSPX2 and OsPHO2. As a result, mutants accumulate higher Pi compared to wildtype plants. The two allelic groups for RAD23a locus also differ in root and shoot phosphorus (P) content. Further, we show that RAD23a interacts with OsSPX2, a negative post-translational regulator of OsPHR2, the master regulator of Pi starvation response. Mutants have higher shoot growth and Pi levels under low Pi conditions, linking enhanced growth of mutants to increased Pi uptake. The UBA2 domain specific mutants have higher single grain weight and per plant grain weight than wildtype. In summary, we show that the RAD23a regulates differential growth, salt response and Pi uptake in rice in a domain-specific manner supporting the moonlighting roles of RAD23a in salt tolerance and phosphorus-dependent shoot growth.

Phenylacetic acid (PAA) is a naturally occurring auxin whose biosynthesis and function during plant regeneration remain poorly understood. PAA may be synthesized from phenylalanine via the CYP79A2-dependent phenylacetaldoxime pathway, in which benzyl cyanide/phenylacetonitrile (BnCN/PAN) is a potential intermediate and substrate for NITRILASE (NIT) enzymes. Here, we investigated whether BnCN/PAN promotes somatic embryogenesis (SE) through NIT-dependent PAA biosynthesis. Low concentrations of BnCN/PAN stimulated somatic embryo formation in Arabidopsis thaliana, whereas exogenous PAA also promoted embryogenic induction. Transcriptome profiling revealed that BnCN/PAN upregulated genes associated with SE, including key embryogenic regulators and EMBRYO DEFECTIVE genes. RNA-seq data further indicated enhanced auxin signalling, which was independently confirmed using the pDR5::GUS reporter line. Inhibition of NIT activity by heatin reduced the embryogenic competence of BnCN/PAN-treated explants, supporting the involvement of NIT enzymes in this response. Collectively, our findings provide the first evidence that BnCN/PAN promotes embryogenic transition and suggest that NIT functions in SE extend beyond their proposed role in indole-3-acetic acid biosynthesis. Summary statementThis study uncovers a previously unrecognized pathway regulating plant regeneration, providing new insights into how naturally occurring metabolites influence embryo formation.

Bluebunch wheatgrass (Pseudoroegneria spicata) exhibits substantial variation in its response to salt stress, making it a valuable model for studying salinity-tolerance mechanisms for use in crop improvement. In this study, we identified two P. spicata genotypes with contrasting responses to salt stress: the tolerant W6 56551, which maintained growth with green foliage under saline conditions, and the susceptible PI693916, which exhibited severe leaf chlorosis and stunted growth. To better understand the molecular basis of salt tolerance in blue-bunch wheatgrass, we conducted RNA-sequencing at 0, 1, and 4 days (D0, D1, and D4) after salt treatment at 160 mM level to examine changes in gene expression of salt-tolerant and salt-susceptible genotypes. Comparative analysis across time points identified 6,154 and 1,086 differentially expressed genes (DEGs) at D4 and D1 in PI693916, and 4,638 and 3,302 DEGs at D4 and D1 in W6 56551, respectively, relative to control (D0). Functional analysis of these DEGs showed that the salt-tolerant geno-type displayed an early and broad transcriptional reprogramming, including induction of photosynthesis, carbon metabolism, and flavonoid biosynthesis pathways, whereas the salt-susceptible genotype exhibited delayed and less coordinated responses, with enrichment of cyanoamino acid metabolism and repression of antioxidant-associated pathways. Notably, calcium signaling, ion transporter regulation, and osmolyte biosynthesis genes showed contrasting expression between genotypes, highlighting distinct strategies for ionic and osmotic homeostasis. Collectively, these results demonstrate that salt tolerance in P. spicata is associated with rapid metabolic adjustment, enhanced photosynthetic stability, and differential regulation of ion transport and osmoprotectant pathways.

Branched-chain amino acids (BCAAs) are essential amino acids involved in protein synthesis and energy metabolism. Because animals cannot synthesize BCAA de novo, plant-derived BCAAs are important to human nutrition. Although mungbean sprouts are widely consumed as functional plant-based food materials, changes in individual BCAA accumulation and their transcriptional regulation during mungbean germination remain poorly understood. In this study, amino acid contents and transcriptomic profiles were analyzed at three germination stages, 8H, 24H, and 72H. Total BCAA content increased during germination, whereas individual BCAAs exhibited distinct temporal accumulation patterns. Isoleucine and valine increased until 72H, while leucine increased during early germination and decreased after 24H. Transcriptome analysis revealed time-dependent expression changes in BCAA biosynthesis and degradation genes associated with the leucine decrease after 24H. These findings suggest that 24H represents an important transition point for BCAA accumulation and compositional change during mungbean germination. This study provides molecular evidence for the regulation of BCAA metabolism during mungbean germination and supports the potential use of germinated mungbean as a plant-based amino acid resource.

Accelerating photoprotective regulation to improve carbon assimilation is a promising strategy to increase crop productivity. Although rapid non-photochemical quenching (NPQ) relaxation has been validated as a target through metabolic engineering, it remains unclear whether conventional breeding has improved this trait. Here, we investigated whether more than a century of soybean breeding enhanced NPQ relaxation alongside light-saturated carbon assimilation and seed traits. We evaluated a historical panel of 24 soybean genotypes across vegetative and reproductive developmental stages by integrating NPQ relaxation, gas exchange parameters, xanthophyll-cycle pigment profiles, expression of key photoprotective genes (VDE, PsbS, and ZEP), seed number and seed weight. NPQ relaxation parameters were not consistently associated with genotype release year, seed number, or seed weight at either developmental stage. The only exception was the amplitude of the rapidly relaxing NPQ component (AqE), which was negatively correlated with all three variables during the reproductive stage. In contrast, genotype release year was positively associated with maximum net CO2 assimilation rate (Amax), maximum carboxylation rate of Rubisco (Vcmax), maximum electron transport rate (Jmax), seed number, and seed weight, while Amax and Vcmax were positively correlated with seed number and seed weight. These findings indicate that the greater photosynthetic capacity of modern genotypes was not accompanied by faster photoprotective response. Thus, photoprotective regulation has not kept pace with gains in photosynthetic capacity under field conditions. We conclude that rapid NPQ relaxation remains an important target for synchronizing photoprotection with the high photosynthetic capacity of modern soybean lines.

Acetic acid (AA), a volatile compound present in diverse microbial-derived biostimulants, enhances drought tolerance in plants. In Arabidopsis, soil-applied AA action has been linked to histone H4 acetylation and activation of jasmonate (JA) signalling. However, the mechanisms underlying AA action in crops of agronomic interest remain poorly understood. Here, we used an integrative approach to evaluate the effects of soil-applied AA on fruit yield, physiological performance, and leaf transcriptomic and proteomic profiles of tomato plants grown under optimal and suboptimal irrigation conditions (OIC and SOIC, respectively). While AA had little effect under OIC, it significantly enhanced fruit yield and photosynthesis under SOIC. Long-term water deficit triggered extensive transcriptomic and proteomic reprogramming, particularly affecting photosynthesis, RNA processing, protein biosynthesis-, modification- and homeostasis-related processes. Under SOIC, AA induced marked molecular changes that were not consistent with activation of canonical JA signaling pathways. Notably, only [~] 10% of the drought- or AA-responsive proteins were associated with corresponding transcript changes, highlighting a predominant role of regulatory layers beyond the transcriptional control to both long-term water deficit- and AA-induced protein remodeling. Strikingly, AA attenuated 47% and 35% of the transcriptomic and proteomic alterations induced by long-term water deficit, respectively. In addition, AA altered the abundance of numerous proteins that do not respond to drought, particularly ribosomal proteins and proteins involved in RNA processing. Collectively, our findings indicate that AA enhances tolerance to prolonged water deficit in tomato through mechanisms largely independent of canonical JA signaling and involving extensive downstream regulatory processes that partially mitigate stress-induced molecular reprogramming.