Plant Physiology and Biochemistry最新文献

Fenugreek (Trigonella foenum-graecum L.) is a highly valued aromatic herb known for its therapeutic, cosmeceutical, and pharmacological uses. The key secondary metabolites of fenugreek, including trigonelline and diosgenin, exhibit noteworthy antidiabetic and anticarcinogenic properties. The present study examines the putative roles of the signaling molecules, such as hydrogen sulfide (H₂S) and nitric oxide (NO), in regulating plant growth and development. The foliar application at concentrations of 0, 25, 50, 100, and 200 μM significantly improved the physiological and agronomic performance of fenugreek. Furthermore, the greatest improvements in growth, photosynthetic efficiency, physiological traits, and secondary metabolite production occurred at optimal concentrations of H₂S (100 μM) and NO (200 μM) compared with the control. The applied concentrations significantly enhanced plant biomass, seed yield, and key traits, including total chlorophyll, carotenoid, and chlorophyll fluorescence. Both elicitors independently accelerate carboxylation efficiency and nitrogen metabolism by stimulating carbonic anhydrase and nitrate reductase activities in fenugreek plants. They also induce the production of antioxidant enzymes (SOD, CAT, POX, APX, and PPO), osmolytes (proline and glycine betaine), phenolic, flavonoid, and alkaloid content in fenugreek. Additionally, H₂S and NO significantly increased trigonelline production compared with the control group, likely through the modulation of redox homeostasis and elicitor-mediated stimulation of antioxidants and secondary metabolite biosynthetic pathways. Overall, the findings provide new evidence that both signaling molecules autonomously regulate primary and secondary metabolism in fenugreek's growth and biosynthetic yield, highlighting their independent roles beyond their well-known interactive effects. Therefore, H₂S and NO can be employed as effective elicitors in a wide range of crops.

The flower is a complex structure, composed of a set of specialized organs that play critical roles in plant reproduction. The reproductive organs are stamens and gynoecia, and the relationship between these two organs is essential for plant reproduction, where pollination and fertilization of the ovules give rise to the seeds. Development of the reproductive organs requires distinct molecular cues that are orchestrated through specialized signaling pathways. These pathways involve molecules that work together at multiple regulatory levels, and understanding these dynamic regulatory networks is crucial. Here, we studied protein-protein interactions of the AP2 transcription factor BOLITA/ENHANCER OF SHOOT REGENERATION 2/DORNRÖSCHEN-like (BOL/ESR2/DRNL), which marks organ founder cells, regulates embryo cell patterning, cotyledon organogenesis, and early organ development in Arabidopsis. BOL is essential for stamen, gynoecium, and fruit development. An in-silico analysis to identify protein interactors of BOL was performed, and various interactors related to development were evaluated in planta. The results demonstrate that the BOL protein-protein interaction network contains a variety of proteins, from key regulators of floral development to unknown proteins. We focused on elucidating the relationship between BOL and the ROXY1 and ROXY2 proteins, which are glutaredoxins involved in flower development. The absence of BOL-ROXY affects stamen, gynoecium and fruit development, and seed-set. We evaluated BOL-ROXY interactions in vitro and determined that both proteins interact physically in a DNA-independent and REDOX-independent fashion. These results suggest that BOL and ROXY1 and ROXY2 play important roles during reproductive development by coordinating floral organ growth.

The apoplasmic unloading pathway is crucial for regulating sugar accumulation in fruits, thereby determining both yield and quality. SWEETs are key facilitators of sugar transport, yet their specific functions in apple fruit sugar accumulation remain unclear. Here, we identified and characterized MdSWEET4 in apple (Malus × domestica Borkh). Spatiotemporal expression, subcellular localization, and yeast complementation assays confirmed that MdSWEET4 encodes a plasma-membrane glucose transporter predominantly expressed in the phloem tissue of fruit vascular bundles. Silencing of MdSWEET4 significantly altered sugar accumulation in apple fruits and upregulated the expression of sucrose transporters. Heterologous overexpression of MdSWEET4 in tomato enhanced soluble sugar accumulation in fruits. MdSWEET4 formed heterooligomers with MdSWEET23, and their co-expression in tomato unexpectedly reduced sugar accumulation. We conclude that MdSWEET4 is a key regulator of sugar unloading and metabolism in apple, and that its interaction with MdSWEET23 may modulate sugar-transport efficiency.

Soil salinity severely constrains rice productivity by inducing ionic imbalance, oxidative damage, and metabolic disruption. Hydrogen sulfide (H₂S) has emerged as an important signaling molecule in plant stress responses, yet its mechanistic role in salinity tolerance remains incompletely understood. Here, we investigated the function of H₂S in modulating salinity stress responses in rice using two cultivars with contrasting salinity tolerance, the sensitive Dongjin and the tolerant IR73. Salinity stress resulted in severe growth inhibition, particularly in Dongjin, accompanied by elevated malondialdehyde and hydrogen peroxide levels. H₂S donor (NaHS) pretreatment significantly alleviated these symptoms and reduced oxidative damage, whereas its scavenger (hypotaurine) exacerbated stress effects. Expression analysis of ion transporter genes revealed cultivar-specific responses, with NaHS selectively stabilizing Na⁺ and K⁺ homeostasis rather than broadly inducing salinity-responsive genes. To further gain a molecular insight into these H₂S responses, we employed data-independent acquisition (DIA) proteomics, which led to the identification of 6710 protein groups and 1635 differentially modulated protein groups. Functional analysis of the H₂S and salinity-responsive proteins revealed coordinated modulation of redox-related enzymes, sulfur metabolism, and regulatory proteins in IR73. In particular, a significant modulation of proteins associated with γ-aminobutyric acid (GABA) metabolism was observed. qRT-PCR-based expression analysis and GABA quantification revealed that H₂S pretreatment suppressed excessive activation of GABA biosynthesis and accumulation, indicating that GABA acts as a marker of stress severity rather than a primary mediator of H₂S-induced tolerance. Collectively, our results demonstrate that H₂S enhances salinity tolerance in rice by reducing stress perception, maintaining redox and ionic homeostasis, and minimizing secondary stress responses, providing new insights into H₂S-mediated stress adaptation mechanisms.

The dehydration-responsive element binding (DREB) subfamily, belonging to the APETALA2/ethylene-responsive element binding (AP2/ERF) superfamily, is crucial for plant growth and development. Despite the identification of DREB genes in numerous plant species, research on the DREB2 family in alfalfa remains incomplete. In this study, we used the alfalfa cultivar "Zhongmu No. 4" to identify and characterize 11 MsDREB2 genes through whole-genome analysis. These genes were unevenly distributed on chromosomes 1 and 2 and on unanchored scaffold chromosomes. A phylogenetic analysis involving Arabidopsis thaliana, Medicago truncatula, and Medicago sativa showed that MsDREB2 members were divided into four clades. Synteny analysis revealed that 45.5% (5 out of 11) of MsDREB2 genes formed segmental duplications, with no tandem duplications observed. The Ka/Ks analysis indicated that some gene pairs underwent purifying and positive selection. Cis-acting elements involved in plant growth, hormone responses, and stress responses were found in the promoters of the MsDREB2 genes. MsDREB2-04 exhibited variable responses to salt and drought stress, determined by qRT-PCR. Under drought stress, the Arabidopsis thaliana dreb2d mutant showed markedly reduced growth. In contrast, MsDREB2-04 overexpression in alfalfa enhanced drought tolerance. Conversely, VIGS silencing of MsDREB2-04 reduced drought tolerance. This study provides a comprehensive identification of the MsDREB2 gene family in alfalfa and confirms the role of MsDREB2-04 in drought stress responses. These findings provide a foundation for functional studies of MsDREB2 genes.

Exposure to indium oxide nanoparticles (In₂O₃-NPs) presents a critical challenge as an emerging soil contaminant that severely impairs plant growth and metabolic health. In this study, In2O3-NP exposure reduced biomass by 58% in alfalfa, driven by excessive indium (In) accumulation, disrupted mineral (P and Fe) balance, and inhibited photosynthesis. This physiological decline led to a significant depletion of sugars and nitrogen metabolites, particularly in the more sensitive alfalfa model. To mitigate these toxic effects, we utilized cyanobacterial priming (CP) with Anabaena laxa to investigate how species-specific metabolic and physiological responses are shaped in alfalfa (legume) and rye (grass). CP treatment differentially mitigated toxicity by reducing In uptake, maintaining nutrient homeostasis, and restoring photosynthetic efficiency. This resulted in improved biomass, with alfalfa showing the most significant recovery. Mechanistically, CP enhanced sugar and nitrogen metabolism, providing the necessary precursors for the accumulation of protective secondary metabolites, such as phenolics and flavonoids, which reduced oxidative damage. Furthermore, CP induced a structural adaptation through the activation of the phenylpropanoid-lignin biosynthetic pathway. In alfalfa, elevated levels of cinnamic and coumaric acids were linked to increased activities of key enzymes, phenylalanine ammonia-lyase (PAL), caffeic acid O-methyltransferase (COMT), cinnamyl alcohol dehydrogenase (CAD), and cinnamoyl-CoA reductase (CCR). This resulted in a substantial 243.6% increase in lignin in alfalfa, compared to a 115.1% rise in rye. This study demonstrates that while rye relies on inherent physiological tolerance, alfalfa exhibits superior metabolic plasticity when primed with CP. These findings prove that alfalfa and rye utilize distinct survival strategies at the biochemical level; while rye leverages its natural resilience, alfalfa undergoes a complete metabolic reorganization to rescue its growth and survive nanoparticle stress.

Sugar content is among the most important agronomic traits in tomatoes. High-sugar tomatoes are usually produced by applying water stress, which results in a significant reduction in fruit yield. We developed a hydroponic method involving the use of coral sand as a solid medium and optimized a nutrient management protocol to produce high-sugar tomatoes while largely maintaining yield. In this study, we analyzed the mechanism by which coral sand increases sugar content. Transcriptome analysis revealed that the expression of phosphorus deficiency-inducible genes increased in the leaves of tomato plants grown on coral sand. The phosphate concentration in both the nutrient solution and leaves decreased when the plants were grown on the coral medium, suggesting that the response to mild low-phosphate conditions may be associated with the increase in sugar content. In addition, under mild low phosphate in hydroponic culture, the sugar content in the fruit increased, even though the fruit yield decreased. Interestingly, comparisons of gene expression levels under these conditions with those from previously reported mild drought experiments showed that homologs of genes that are induced by coral sand were also upregulated in response to mild drought. Collectively, our findings reveal a previously unrecognized ability of hydroponic cultivation using coral sand to create mild low-phosphate conditions that trigger sugar accumulation pathways associated with mild drought. This study not only provides a practical strategy for producing high-sugar tomatoes using a coral sand cultivation system with minimal impact on yield, but also suggests a role for low-phosphate responses in regulating sugar accumulation in fruits.

Drought stress occurs intermittently and severely constrains plant growth and production. Constitutive overexpression of stress-responsive genes can improve drought tolerance but often imposes unnecessary metabolic costs under favorable conditions. Stress-inducible promoters therefore represent an important regulatory resource for precision engineering of drought tolerance. In this study, a drought-inducible promoter from switchgrass (Panicum virgatum L.), PvHVA1pro, derived from the late embryogenesis abundant gene PvHVA1 (Hordeum vulgare aleurone 1) was identified and functionally validated. Transcript analysis showed that PvHVA1 expression is strongly induced by PEG-mediated osmotic stress, with minimal basal expression under non-stress conditions. Stable transgenic switchgrass expressing PvHVA1pro::GUS exhibited drought-dependent and reversible promoter activity in vegetative tissues. To demonstrate its practical utility, PvHVA1pro was used to drive the aquaporin gene PvPIP2;9 in switchgrass that the inducible expression of PvPIP2;9 enhanced drought tolerance, photosynthetic performance, and water-use efficiency compared with wild-type plants, without pronounced growth penalties. Together, these results establish PvHVA1pro as a sensitive, low-basal, drought-inducible promoter resource for switchgrass, providing an enabling regulatory tool for functional genomics and precision drought-tolerance engineering in bioenergy crops.

Cinnamomum camphora var. linaloolifera is a primary source of natural linalool, an acyclic monoterpene with high industrial value, yet the molecular basis of its high-purity accumulation remains poorly understood. In this study, we characterized 'Nan'an 1', an elite cultivar, identifying it as a unique chemotype with exceptional linalool purity (88.30%) and negligible metabolic byproducts via comparative metabolomics. Genome-wide analysis identified 46 CcTPS genes, revealing a significant expansion of the TPS-b subfamily. Notably, the TPS-g subfamily clustered closely with TPS-b but exhibited a specific loss of the cyclization-associated RRX8W motif. This structural divergence provides a theoretical basis for the functional specialization of TPS-g in acyclic monoterpene biosynthesis. Transcriptomic and qRT-PCR analyses revealed that the high expression of four TPS-g candidates (CcTPS14, CcTPS15, CcTPS16, and CcTPS32) significantly correlates with linalool accumulation. Furthermore, heterologous expression in Escherichia coli and in vitro enzymatic assays conclusively demonstrated that these four recombinant proteins function as highly specific linalool synthases, efficiently converting geranyl diphosphate (GPP) into linalool. These findings suggest that the TPS-g subfamily likely originated from the TPS-b lineage through the specific loss of the RRX8W domain, thereby specializing in linalool synthesis. This study elucidates the genetic and molecular mechanisms of high-purity linalool accumulation, offering precise target genes for metabolic engineering.

The basic helix-loop-helix (bHLH) transcription factors MYC2 and its paralogs are master regulators in jasmonate (JA) signaling in Arabidopsis, yet their functions in potato (Solanum tuberosum) remain poorly understood. Here, we identified and characterized StMYC1, a potato transcription factor that clusters phylogenetically with tomato SlMYC1 and contains conserved JASMONATE ZIM-DOMAIN (JAZ)-interacting and bHLH domains. Overexpression of StMYC1 in Arabidopsis recapitulated canonical JA-hyperresponsive phenotypes in plant development and defense responses, confirming its functional conservation in the JA signaling pathway. Yeast two-hybrid assays demonstrated that StMYC1 interacts with Arabidopsis JAZ repressors and potato StJAZ1-like, indicating its integration into the core JA signaling module. Transcriptome analysis revealed that StMYC1 reprograms the gene expression profile in Arabidopsis leaves to enhance defense-related gene expression while repressing genes associated with plant growth. Strikingly, overexpression of StMYC1 in potato conferred a dual beneficial effect, including increased microtuber yield under in vitro conditions and enhanced resistance to Spodoptera exigua. Physiological and molecular analyses showed that StMYC1 improves photosynthetic capacity in source leaves and upregulates the expression of genes involved in sucrose transport, starch biosynthesis, and tuberization in sink microtubers. Moreover, StMYC1 enhances the constitutive and inducible accumulation of steroidal glycoalkaloids (SGAs), as well as the inducible expression of JA-responsive defense genes, in potato leaves. Our work demonstrates that StMYC1 is a conserved JA signaling component that coordinately improves herbivore resistance and microtuber production in potato likely by enhancing source capacity and redirecting resource allocation to favor both tuber storage and leaf defense. These results highlight StMYC1 as a promising target for breeding potato varieties with enhanced herbivore resistance and tuber yield, and provide insights for the genetic improvement of other storage-organ crops.