Physiologia Plantarum

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

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.

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.

Tomato production, yield and fruit quality face major challenges due to several factors, including the complex polygenic inheritance of agronomically relevant traits, biotic and abiotic stresses, and increasingly stringent regulations limiting the use of phytosanitary products. In this context, bioinoculants have emerged as a sustainable strategy capable of enhancing yield without compromising fruit quality, conferring protection against different stresses and exerting a minimal or no impact on environment and human health. In this study, we evaluated the effects and the underlying mechanisms by which Streptomyces sp. N2A, an actinobacteria isolated from soybean rhizosphere, promotes seed germination, vegetative growth and yield in tomato, without modifying fruit quality. The obtained results demonstrated that the bacterial treatment significantly improved seedlin[g]s emergence and growth and development in vegetative stage. At harvest, yield was also significantly enhanced, mainly driven by increased individual fruit weight, which was positively correlated with a thicker pericarp in fruits from N2A-treated plants. Transcriptional analysis during fruit development revealed a coordinated induction of auxin and cytokinin signaling pathways before and after anthesis, providing a hormonal framework that underlies the promotion of pericarp growth. This study provides evidence of the beneficial effect of inoculation with Streptomyces sp. N2A on tomato yield and constitutes the first report describing the modification of fruit morphology and expression of genes involved in phytohormonal modulation during early growth and development, induced by a plant growth-promoting Streptomyces.

Climate change is increasing the frequency and intensity of heatwaves and droughts, threatening medicinal and aromatic plants (MAP) production. Temporary shading during the hottest part of the day may reduce heat and radiative stress while limiting the reduction in light availability. We evaluated this strategy in a field experiment using three MAP species with contrasting ecological requirements and harvested organs: lavandin (Lavandula x intermedia), curly parsley (Petroselinum crispum) and valerian (Valeriana officinalis). Vertical shade nets provided midday shading and effects on crop microclimate, leaf temperature, water status, PSII photochemical efficiency, plant growth and biomass and essential oil production were assessed over two growing seasons. Midday shading reduced daily photosynthetically active radiation by 19.9-55.9 %, with weak effects on air temperature and vapor pressure deficit. In contrast, leaf temperature at solar noon decreased by 6.9 degrees C, 5.6 degrees C and 3.0 degrees C in lavandin, valerian and parsley, respectively. Midday shading improved light-adapted and maximum PSII photochemical efficiencies in all three species and reduced branch dehydration in lavandin during heatwave periods. However, agronomic responses were species-dependent. Floral biomass decreased in lavandin, whereas parsley leaf biomass and valerian root biomass increased. Essential oil concentration was unaffected in lavandin and valerian. Overall, our results show that midday shading primarily reduced leaf-level thermal and radiative stress rather than modifying the surrounding air microclimate, and suggest that its agronomic effects may reflect a balance between stress alleviation and reduced carbon acquisition, that varies with species ecology and production objectives.

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.

Plants produce a variety of O-prenylated aromatics that exhibit biological activities beneficial to human health, and the presence of the O-prenyl moiety is often crucial to their functions. However, most aromatic O-prenylation genes remain unknown in plants. In this study, we report the molecular identification of an aromatic O-prenyltransferase (PT) involved in the biosynthesis of auraptene (7-geranyloxycoumarin), a citrus metabolite known for its preservative effect on human cognitive function. Based on in silico screening focusing on the membrane-bound PT family, CpPT4 was isolated as a candidate from grapefruit (Citrus x paradisi), an auraptene-rich species. Enzymatic characterization demonstrated that recombinant CpPT4 specifically catalyzes umbelliferone 7-O-geranyltransferase activity to form auraptene, which differs from the enzymatic functions of known O-PTs. This enzyme also catalyzed aromatic N-prenylation to produce a new-to-nature auraptene analog. Regarding organ- and organellar-specific localization, it is strongly suggested that CpPT4 functions in the outer pericarp plastids, where auraptene is expected be formed. Furthermore, we found that CpPT4 orthologs are widely distributed in citrus genomes. Intriguingly, mandarins and their descendant species possess dysfunctional orthologs, which is consistent with the low accumulation of auraptene and its downstream metabolites in these species. This study provides an example of the contribution of the UbiA superfamily to O-prenylated aromatic biosynthesis. Moreover, CpPT4 can be useful as a tool in the synthetic biology-based production of auraptene and its analogs, as well as a molecular marker in the breeding of auraptene-rich citrus varieties.

Plants frequently experience recurrent drought events separated by periods of rehydration. Although drought imposes strong constraints on plant physiology, prior exposure may alter subsequent stress responsiveness through memory-based mechanisms. Here, we investigated whether recurrent drought at distinct developmental stages establishes stress memory in sugarcane and whether this response persists across vegetative propagation. Two genotypes contrasting in drought tolerance and productivity (IACCTC07-8008 and IACSP95-5000, respectively) were grown under greenhouse conditions and subjected to three drought cycles imposed either at tillering or maturation stage. Gas exchange, photochemical performance, leaf water status, primary metabolite profile, and growth traits were assessed across cycles, and vegetative propagules were subsequently evaluated under renewed drought. The first drought cycle imposed strong limitations on carbon assimilation and photochemistry in both genotypes and developmental stages. However, subsequent cycles resulted in attenuated reductions in A and g, improved intrinsic water use efficiency, and partial stabilization of PSII performance, indicating a modified stress-response trajectory. Young plants displayed earlier improvements (from the second cycle), whereas in mature plants this shift was evident mainly during the third cycle. Recurrent drought promoted sustained reorganization of amino acid, carbohydrate, organic acid and polyol metabolism alongside increased root biomass and higher relative water content during later cycles. Importantly, propagules derived from drought-conditioned plants exhibited faster recovery of photosynthetic performance and reduced cumulative physiological impairment under renewed drought, despite showing similar stress sensitivity at maximum water deficit. This persistence of enhanced recovery capacity across vegetative propagation indicates that drought-induced memory was maintained beyond the initially stressed plants. Together, our findings demonstrate that recurrent drought establishes a metabolically imprinted state in clonal sugarcane, integrating physiological adjustment, metabolic reprogramming, and whole-plant acclimation. These results highlight the potential of stress memory as a mechanism supporting resilience in perennial crops exposed to increasingly recurrent drought events.

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/741208v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1238a49org.highwire.dtl.DTLVardef@4bc55corg.highwire.dtl.DTLVardef@8a277aorg.highwire.dtl.DTLVardef@25c625_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO C_FIG Legume-rhizobium symbiosis is constrained by carbon allocation and nutrient exchanges between the host plant and symbiotic bacteroids, emphasizing the necessity of biostimulant-based strategies to improve symbiotic efficiency. Studies suggest that plants provide carbon substrates (mainly TCA cycle intermediates) and nitrogen assimilation precursors to support bacteroid metabolism and nitrogen fixation. The GABA shunt represents a conserved bypass, linking the GS/GOGAT cycle, TCA cycle, and broader nitrogen metabolism. In the present study, the metabolic phenotypes upon rhizospheric application of exogenous {gamma}-aminobutyric acid (GABA) and succinate were investigated in pea. Application of exogenous GABA and succinate primarily altered the morpho-biochemical properties and root nodule establishment of the plant. While GABA supplementation reduced the root length and increased stomatal density, succinate treatment alone inhibited nodule organogenesis with disrupted symbiosome zoning. Metabolic rewirings associated with these phenotypic changes begin at the root nodule compartment, where exogenous GABA altered endogenous tricarboxylic acid (TCA) cycle pools, leading to higher turnover of TCA cycle intermediates, including succinate, fumarate, and malate, as well as elevated levels of sugars (sucrose, glucose, and fructose) and polyols (pinitol, mannitol, and myo-inositol). Concurrently, the plants accumulated substantially higher levels of asparagine (+3.9 log10-fold higher), accompanied by altered shoot protein content and enhanced elemental nitrogen content (+0.8-1%). Collectively, these findings demonstrate the potential of GABA as a biostimulant capable of altering the carbon-nitrogen dynamics and enhancing symbiotic functioning in pea root nodules, whereas succinate alters the process of nodule formation.

Legumes establish mutualistic symbiosis with nitrogen (N)-fixing bacteria, which allows them to utilize atmospheric N2. Because the maintenance of symbiosis requires abundant carbon (C) sources, legumes regulate the balance between carbon consumption and nitrogen acquisition by systemically controlling the nodule number through CLAVATA1 (CLV1)-like receptors. In Lotus japonicus, the CLV1-like receptor HYPERNODULATION ABERRANT ROOT FORMATION1 (HAR1) acts in shoots to regulate root nodulation and contributes to symbiotic C/N coordination. This raises the possibility that HAR1 may also influence plant growth and nitrogen utilization beyond symbiotic nodulation. In this study, we showed that HAR1 plays a critical role in regulating nitrogen use to enhance growth under conditions of high nitrate availability, even in non-symbiotic environments. Unlike the wild-type, the har1 mutant failed to increase its growth in response to higher nitrate availability. This lack of growth response was associated with a lower rate of net biomass production per unit leaf area and a reduced capacity for biomass production per unit plant nitrogen. We further found that nitrate-responsive TCA cycle-related organic acids were higher in har1 leaves than in wild-type leaves even under low nitrate conditions. Because the HAR1 mutation did not affect photosynthetic traits, we propose that HAR1 promotes growth under non-symbiotic conditions by coordinating nitrogen utilization with primary metabolism. One-sentence summaryLotus japonicus CLV1-like receptor HAR1 improves nitrogen utilization and growth at high nitrate conditions by regulating organic acid metabolism, independent of root nodule symbiosis.

The ability of seeds to survive until dormancy recedes and the germination requirements are met is an adaptive strategy. Proteomics improves our understanding of the mechanisms that control the adaptation to environmental heterogeneity. In this study, we investigated two European beech populations from different habitats that differed in dormancy and germination traits. We found that the populations exhibited different germination strategies, which were reflected in coordinated but quantitatively different proteomic reprogramming. The Miekinia population exhibited stronger accumulation of proteins involved in nucleotide sugar biosynthesis, S-adenosylmethionine metabolism, and flavonoid biosynthesis. Enhanced nucleotide sugar biosynthesis indicates more intensive cell wall remodelling and carbohydrate metabolism, which support embryo growth and faster germination. Increased S-adenosylmethionine metabolism suggests the epigenetic and hormonal regulation of germination differences between populations. Higher flavonoid biosynthesis indicates an enhanced antioxidant capacity associated with environmental protection. In contrast, the Wisa population showed stronger accumulation of proteins involved in RNA processing, suggesting tighter post-transcriptional regulation and proteome reorganization during germination. Consistent with its deeper dormancy and later germination, the Wisa population appears to rely more on RNA-level regulation, whereas the Miekinia population prioritizes metabolic activation. These contrasting proteomic profiles likely reflect population-specific physiological strategies associated with dormancy depth and adaptation to different climatic conditions. HighlightProteomic reprogramming reveals population-specific germination strategies in European beech, linking dormancy depth with contrasting metabolic activation and RNA-level regulation during the transition from dormancy to germination.

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.

Understanding the genetic architecture of ecophysiological traits related to carbon gain and water loss is crucial to develop cultivars tolerant to abiotic stresses and that maintain productivity in the context of climate change. This can be achieved both through experiments in the greenhouse on potted plants under controlled conditions and in the field. However, the stability of genetic determinism of ecophysiological traits across environmental conditions has rarely been evaluated. We studied a grapevine diversity panel grown both in a greenhouse and in the field, to investigate the impact of growing conditions on leaf ecophysiological traits related to leaf morphology, fluorescence, gas exchange and water use efficiency. The correlation structure between traits was conserved within each environment even though, for most traits, cultivars ranking was not conserved between both environments. However, a set of cultivars, sharing the same functioning pattern in terms of gas exchange and fluorescence in both environments, was identified. Single- and multi-environment Genome-Wide Association Studies (GWAS), based on a dense genotyping matrix, were used to dissect the genetic architecture of leaf traits. The Quantitative Trait Loci (QTLs) identified through single-environment analyses differed substantially from those detected using multi-environment ones. Multi-environment approaches highlighted shared QTLs across environments for gas exchange and fluorescence traits. Candidate genes associated with carbon- and water-related functions were further identified in these genomic regions. Despite the weak correlation between greenhouse and field trait values, combining both environments enabled the identification of robust genetic regions associated with ecophysiological traits of interest.

Soybean, a widely cultivated leguminous crop valued for its protein, amino acids, and oil, faces the challenge of maintaining protein levels, which have an inverse correlation with yield. Reducing leaf chlorophyll levels could increase seed protein levels without compromising yield; however, this is yet to be tested. Therefore, to understand the impacts of low chlorophyll mutations on soybean yield and seed composition, we screened and compared 25 low chlorophyll soybean mutants to their 11 dark green parents. PI548210 (Lincoln mutant) demonstrates a higher concentration of protein without affecting yield compared to its dark green parent PI548362 (Lincoln), suggesting it as a good candidate for further large-scale field trials. PI547555 (Y11/y11, Clark mutant) demonstrates a lower concentration of oil without impacting yield, alongside lower gross photosynthesis, but with chlorophyll levels in the pod and seed tissues that are comparable to its dark green parent PI548533 (Clark). These findings are consistent with the oil concentration of the soybean being influenced by pod and seed photosynthesis, which is correlated with pod height and row spacing. Chlorophyll levels in the leaf do not necessarily correlate with those in the pod and seed of low chlorophyll mutants, possibly due to substantially lower expression of chlorophyll synthesis genes in the pod and seed. SIGNIFICANCEO_LIPI548210 (Lincoln mutant), one of twenty-five low chlorophyll soybean mutants, demonstrates a higher concentration of soybean protein without affecting yield compared to its dark green parent (Figure 1 and Table 1). C_LIO_LIPI547555 (Y11/y11, Clark mutant), a low chlorophyll soybean mutant, demonstrates a reduced concentration of soybean oil without impacting yield, alongside lower gross photosynthesis in pod and seed tissues compared to its dark green parent (Figures 3 and Table 2). These findings suggest that the oil concentration of the soybean is influenced by pod and seed photosynthesis, which is in turn influenced by pod height and row spacing (Figure 2). C_LIO_LIChlorophyll levels in the leaf do not necessarily correlate with those in the pod and seed of low chlorophyll mutants, possibly due to substantially lower expression of chlorophyll synthesis genes in the pod and seed (Figure 5-6). C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/744892v1_fig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@4282dcorg.highwire.dtl.DTLVardef@9d565forg.highwire.dtl.DTLVardef@1918292org.highwire.dtl.DTLVardef@1359b1_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Two low chlorophyll mutants are as healthy as their dark green parents. Lincoln and its low chlorophyll mutant, left; Clark and its low chlorophyll mutant, known as Y11/y11, right. It can be seen by eye that the plants have low chlorophyll (light green/yellow leaves) but a similar growth habit to their dark green parents. See Supplemental Figures 1-4 for contrast, where low chlorophyll mutants are stunted in growth compared to their dark green parents. C_FIG O_TBL View this table: org.highwire.dtl.DTLVardef@657ec9org.highwire.dtl.DTLVardef@166e75borg.highwire.dtl.DTLVardef@df23c7org.highwire.dtl.DTLVardef@1a60124org.highwire.dtl.DTLVardef@194ed96_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOTable 1.C_FLOATNO O_TABLECAPTIONComparison of seed yield, weight, seed composition between low chlorophyll mutants and their dark green parents. ANOVA is used with linear mixed model (random effect = block, fixed effect = variety). Least squares mean is used to compare. For yield and seed composition, N=4 blocks. For leaf chlorophyll (SPAD), N=40. Yield is average yield per plant (g). n.s. = not significant. C_TABLECAPTION C_TBL O_FIG O_LINKSMALLFIG WIDTH=179 HEIGHT=200 SRC="FIGDIR/small/744892v1_fig3.gif" ALT="Figure 3"> View larger version (26K): org.highwire.dtl.DTLVardef@7a368aorg.highwire.dtl.DTLVardef@192b8f0org.highwire.dtl.DTLVardef@1abb738org.highwire.dtl.DTLVardef@89e978_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 3.C_FLOATNO Light response curve of low chlorophyll mutant (Y11/y11, PI547555) and its parent (Clark, PI548533). Rates of net and gross photosynthesis of low chlorophyll (white) and dark green parents (black) pods under field conditions. Each dot represents a value (n=4) {+/-}SE. We assumed that the seeds greatly inhibited the transmittance of light through the pod and used photosynthetic photon flux density for a single-side. C_FIG O_TBL View this table: org.highwire.dtl.DTLVardef@3f0528org.highwire.dtl.DTLVardef@16ba712org.highwire.dtl.DTLVardef@a5ab2aorg.highwire.dtl.DTLVardef@889254org.highwire.dtl.DTLVardef@3efa4f_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOTable 2.C_FLOATNO O_TABLECAPTIONPod photosynthetic parameters for low chlorophyll mutant (Y11/y11, PI547555) and its parent (Clark, PI548533). Photosynthesis was measured 1 September through 15 September 2021 at the University of Illinois Energy Farm in Urbana, IL, USA. The statistical analysis was done using ANOVA with linear mixed model (alpha=0.05). N=4 {+/-} SEM for Clark and N=3 {+/-} SEM for Y11. C_TABLECAPTION C_TBL O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/744892v1_fig2.gif" ALT="Figure 2"> View larger version (23K): org.highwire.dtl.DTLVardef@a36c26org.highwire.dtl.DTLVardef@1116c8forg.highwire.dtl.DTLVardef@ee5e61org.highwire.dtl.DTLVardef@1766712_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 2.C_FLOATNO Low chlorophyll mutant (Y11/y11, PI547555) and its parent (Clark, PI548533) differ in concentration of seed oil, which interacts with height of pod and row spacing. The box plots show the median (central line), the lower and upper quartiles (box) and the minimum and maximum values (whiskers). The statistical analysis was done using ANOVA with linear mixed model (n=3 blocks, alpha=0.05). Least squares mean is used to compare. N.s., non- significant in the analysis. A. Concentration of oil in low chlorophyll mutant seeds from the upper canopy decreased by 4% compared to the dark green parent (18.2% vs 19%) while there was no difference between them in the seeds from the lower canopy (20.2% vs 20.6%). B. Schematic layout of 2013 field setting showing two different row spacings. C. Concentration of oil in low chlorophyll mutant decreased by 2% in 38cm spacing (21.4% vs 22%) while there was no difference in 19cm spacing (21.3% vs 21.7%) in 2013 field. C_FIG O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=162 SRC="FIGDIR/small/744892v1_fig5.gif" ALT="Figure 5"> View larger version (22K): org.highwire.dtl.DTLVardef@68e508org.highwire.dtl.DTLVardef@94a6ccorg.highwire.dtl.DTLVardef@152a187org.highwire.dtl.DTLVardef@1eae137_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 5C_FLOATNO (greenhouse). Correlation between the level of leaf chlorophyll (x-axis: SPAD reading) and the level of immature pod or seed chlorophyll (y-axis, mg/g DW). Line represents the linear regression model. R-squared is a coefficient of determination, the percentage of the response variable variation that is explained by the linear model. Pod is labeled by the fresh weight of seeds it contained. A. Level of chlorophyll of 25-100mg pod (n=18). B. Level of chlorophyll of 100-200mg pod (n=17) . C. Level of chlorophyll of 25-100mg seed (n=17). D. Level of chlorophyll of 100-200mg seed (n=20). C_FIG O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=180 SRC="FIGDIR/small/744892v1_fig6.gif" ALT="Figure 6"> View larger version (28K): org.highwire.dtl.DTLVardef@167fd88org.highwire.dtl.DTLVardef@361472org.highwire.dtl.DTLVardef@786325org.highwire.dtl.DTLVardef@1b53855_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 6.C_FLOATNO Levels of gene expression in chlorophyll synthesis pathway. A. CHL common pathway genes; Glutamyl-tRNA reductase (GluTR). Glutamate 1- semialdehyde aminotransferase (GSA-AT). ALA dehydratase (ALAD). Uroporphyrinogen III synthase (UROS). Uroporphyrinogen III decarboxylase (UROD). Protoporphyrinogen IX oxidase (PPO). B. Mg branch; Mg-chelatase (Mgch). Magnesium-protoporphyrin IX monomethyl ester cyclase (MPEC). Protochlorophyllide reductase (POR). 3,8-divinyl protochlorophyllide a 8-vinyl-reductase (4VCR). Heme pathway; Ferrochelatase (FECH). Heme oxygenase (HO). Phytochromobilin synthase (HY). Data come from Severin et al (2010). RPKM, reads per kilobase per million mapped reads. DAF, days after flowering. The source seed is experimental line A81-356022 which was generated by introgressing G. soja (PI468916) into G. max (A81-356022). C_FIG

Potato is the worlds fourth major staple crop, and tuber starch is a critical dietary energy source and a food processing raw material. In this study, hybrid progenies of the high-starch cultivar Huasheng No.7 and China main commercial varieties were used as materials, high-throughput sequencing was performed on tuber samples at tuber bulking, maturation and storage stages. Combined with bioinformatics analysis, parent-progeny resequencing, SNP screening, the regulatory mechanism of tuber starch metabolism was explored. The results showed significant stage-specific transcriptional reprogramming in potato tubers: few differentially expressed genes (DEGs) were identified at tuber bulking and maturation stages, but massive transcriptional changes occurred during storage. XET family genes regulated cell wall remodeling and carbon translocation across all stages, and WRKY transcription factors specifically controlled starch homeostasis in stored tubers. The DEGs at different stage were induced by the SNPs from their parent, and the allele from the high-starch parent, Huasheng 7 may contribute the high-starch allele to the offsprings. One key gene, Soltu.DM.02G019910, which encoded {beta}-glucosidase, have a negatively relationship with tuber starch concentration. The low-starch potato breeding tubers shown higher significantly {beta}-glucosidase activity than high-starch breeding population at maturation stage. This study clarifies the molecular regulatory network of potato tuber starch metabolism and screens core regulatory genes from the tuber bulking stage to tuber storage, thereby providing theoretical support and genetic resources for molecular breeding of high-starch and storage-resistant potato varieties.

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.

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

Background and AimsThe genus Solanum including the wild species S. dulcamara, is rich in specialized metabolites such as steroidal glycoalkaloids (SGAs). Yet, much of this chemical diversity remains poorly characterized. This study aims to provide a comprehensive assessment of intra-specific chemodiversity in S. dulcamara. Using a dataset generated from 42 globally distributed accessions, we tested whether metabolic profiles differ among plant organs. We postulated that metabolic richness and abundance vary across accessions. Additionally, we hypothesized that differences in geographic origin or altitude affect SGA chemodiversity. MethodsAn untargeted metabolomic approach was applied to leaf, flower and root samples of 42 S. dulcamara accessions. Plants were grown in the greenhouse, and the extracted metabolites were analyzed using UHPLC-HRMS/MS in positive and negative ionization modes. Data processing and metabolite annotation were performed with a tailored bioinformatics workflow. Multivariate analyses were performed to evaluate chemical variation across organs and accessions. Key ResultsOur analyses revealed both organ and accession-specific metabolic diversity. Principal component analysis and clustering analyses revealed metabolic differentiation between leaves, flowers and roots. Leaves showed the highest metabolite richness and abundance, while roots showed the lowest. Alkaloids, especially SGAs, dominated positive mode profiles in roots, whereas shikimates and phenylpropanoids were prominent in negative mode profiles. Based on the leaf and flower SGAs profiles, four chemotypes were identified. Analyses of flavonoid and cinnamic acid derivatives, however, did not reveal chemotypes. Feature-based molecular network analyses confirmed that metabolite clusters are associated with plant organs, but not with altitude or geographic origin of the accessions. ConclusionsThe intraspecific chemodiversity within S. dulcamara is mainly driven by organ and accession-specific metabolic differences. We identified four SGA leaf and flower chemotypes, suggesting possible functional and ecological roles of this aboveground chemodiversity. These insights may contribute to applied research in plant resistance breeding and crop production.

Apple scar skin disease (ASSD), caused by Apple scar skin viroid (ASSVd), is characterized by peel scarring, cracking, dappling, and fruit deformation, resulting in reduced fruit quality and marketability. Despite its economic importance, the physicochemical and metabolic alterations underlying disease progression remain poorly understood. To address this knowledge gap, apple fruits representing four stages of ASSD (healthy, lightly infected, moderately infected, and highly infected) were comprehensively characterized. ASSVd infection was confirmed by RT-PCR, amplicon sequencing, and phylogenetic analysis. Fruit morphology and quality attributes, including firmness, total soluble solids (TSS), pH, titratable acidity (TA), and total phenolic content (TPC), were evaluated. ASSVd infection significantly reduced fruit weight and firmness and altered TSS and TA, indicating progressive deterioration of fruit quality. To investigate the underlying metabolic changes, peel and pulp tissues were analysed separately using gas chromatography-mass spectrometry (GC-MS), while major soluble sugars were quantified by 1H nuclear magnetic resonance (1H NMR) spectroscopy. Integrated metabolomic analyses revealed distinct tissue-specific metabolic reprogramming during disease progression. Major soluble sugars declined significantly during early infection, followed by tissue-dependent recovery at later stages, whereas organic acids, amino acids, phenolics, lipids, polyols, and pentacyclic triterpenoids exhibited dynamic stage-dependent changes. Notably, lupeol accumulated progressively, whereas ursolic acid and oleanolic acid declined, indicating disease-associated alterations in host triterpenoid metabolism. Multivariate analyses demonstrated clear metabolic separation among disease stages. Lupeol, ursolic acid, and chlorogenic acid were identified as candidate discriminatory metabolites in the peel, whereas myo-inositol, chlorogenic acid, and aspartic acid were identified in the pulp. Collectively, these findings demonstrate that ASSD induces coordinated, tissue-specific physicochemical and metabolic reprogramming that compromises postharvest fruit quality and reshapes defence-associated metabolism. This study provides the first integrated metabolomic characterization of ASSD progression and identifies potential metabolic biomarkers for disease diagnosis and severity assessment. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/741181v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@92e453org.highwire.dtl.DTLVardef@1cc2436org.highwire.dtl.DTLVardef@15d7e27org.highwire.dtl.DTLVardef@1056568_HPS_FORMAT_FIGEXP M_FIG C_FIG

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.