Plant, Cell & Environment最新文献

Bud dormancy poses a major constraint for tree peony growth and flowering, especially in off-season cultivation. While GATA transcription factors regulate ABA-mediated seed dormancy, their role in bud dormancy remains unclear. In this study, we characterized the GATA family in tree peony and identified two key transcription regulators, PlGATA1 and PlGATA6, that displayed antagonistic expression patterns in dormant and non-dormant buds of Paeonia × lemoinei 'High Noon'. Exogenous ABA treatment induced PlGATA1 expression while suppressing PlGATA6, indicating divergent roles in ABA signalling. Heterologous expression in Arabidopsis revealed that PlGATA1 enhanced seed dormancy, whereas PlGATA6 suppressed it. Transient transformation assays in tree peony showed that PlGATA1 overexpression or PlGATA6 silencing induced bud dormancy and altered the expression of the ABA metabolism gene. Critically, in vivo and in vitro binding assays confirmed that PlGATA1 activates the PlABI5 promoter, while PlGATA6 activates the PlCYP707A2-1 promoter. Collectively, our results establish PlGATA1 and PlGATA6 as an antagonistic transcriptional module that fine-tunes ABA homoeostasis, thereby acting as a molecular switch controlling bud dormancy in tree peony. This study provides novel insights into the transcriptional regulation of bud dormancy and suggests potential targets for improving off-season cultivation in woody plants.

Accumulating evidence shows that reversible protein S-nitrosylation is essential for H₂O₂ homoeostasis and signalling. However, roles for denitrosylation in such oxidative signalling remain poorly understood. Here, we examined this question using the Arabidopsis catalase-defective mutant, cat2, in which oxidative stress induces both glutathione accumulation and salicylic acid (SA) pathways. Induction of these pathways was accompanied by enhanced thioredoxin (TRXH5) expression, and oxidative stress-induced activation of the SA pathway was compromised when TRXH5 expression was genetically disabled, whereas TRXH5 overexpression stimulates H₂O₂-triggered SA responses. Intriguingly, TRXh5-reinforced SA responses were antagonised by glutathione (GSH) deficiency when introducing additional pad2 mutation, localised in the GLUTAMATE-CYSTEINE LIGASE gene encoding the first enzyme of glutathione biosynthesis. Further analysis revealed that the two active cysteine residues of recombinant TRXh5 can be denitrosylated by GSH. Blocking glutathione accumulation increased more TRXh5-SNO formation in TRXH5-YFP cat2 pad2 trxh5 than in TRXH5-YFP cat2 trxh5. Furthermore, S-nitrosoglutathione reductase (GSNOR) was capable of physically interacting with TRXh5, and was also required for GSH-dependent TRXh5 denitrosylation and TRXh5-enhanced SA responses during oxidative stress. Collectively, these data suggest that GSH/GSNOR constitutes an active denitrosylating module that works together with the canonical NADPH-dependent TRX-reducing pathway to sustain cytosolic TRXh5 operation within the oxidative signalling framework.

Woody plants are fast-growing and ecologically important, with widespread applications in urban landscaping and ecological restoration. However, limited understanding of the molecular mechanisms underlying adventitious shoot regeneration has hindered advances in tissue culture and genetic improvement of woody species. Here, we present a comprehensive framework for elucidating adventitious shoot regeneration in Robinia pseudoacacia. Histological analyses delineated key developmental stages, while RNA-sequencing and hormone profiling highlighted the critical roles of auxin and cytokinins. WGCNA analysis identified hormone-responsive regulatory modules, and chemical inhibition assays confirmed their essential functions in adventitious shoot formation. Notably, we discovered that RpARF19 and RpARR12 directly bind to the RpWOX4 promoter to activate its expression and that RpWOX4, in turn, binds to the RpLBD4 promoter to drive expression. In addition, RpARF19 can directly bind to the promoter of RpLBD4 to activate its expression. Overexpression of RpWOX4 or RpLBD4 significantly enhanced adventitious shoot regeneration. Collectively, these findings establish RpWOX4 as a central integrator of auxin and cytokinins signalling and reveal a novel RpARF19/RpARR12-RpWOX4-RpLBD4 regulatory module that orchestrates adventitious shoot regeneration. This study provides new mechanistic insights into adventitious shoot regeneration in woody species and promising strategies for improving tissue culture and breeding approaches.

Aluminium (Al) toxicity in acidic soils severely inhibits root growth and plant productivity. While organic acid exudation (malate, citrate and oxalate) is a key Al-tolerance mechanism, the transporters and regulatory networks in tomato (Solanum lycopersicum) remain poorly characterised. Here, we identified the slow anion channel SlSLAH1 as a plasma membrane-localised malate transporter essential for Al tolerance. Under Al stress, the transcription factor SlSTOP1 and its enhancer SlSZP1 accumulated and formed a complex that directly bound to the SlSLAH1 promoter, activating its expression and enhancing malate exudation from roots. Concurrently, Al stress induced SlSLAH2 expression independently of SlSTOP1. SlSLAH2 interacted with SlSLAH1 to form a heteromeric complex at the plasma membrane, which synergistically facilitated malate exudation. Genetic analyses confirmed that knockout mutants of Slslah1 or Slslah2 exhibited reduced malate exudation and increased Al sensitivity, while SlSLAH1 overexpression lines showed enhanced Al tolerance. Our study unveils a regulatory module where the SlSTOP1-SlSZP1 complex and SlSLAH1-SlSLAH2 heteromeric complex jointly orchestrate malate exudation to confer Al tolerance in tomato, providing mechanistic insights into aluminium detoxification and developing aluminium-tolerant germplasm.

Arsenic (As) is one of the most problematic environmental toxins. Exposure to As, predominantly via drinking water and the intake of food, represents a major human health threat. Various species of As exist in the environment, among them organic and inorganic thioarsenates. Their ubiquitous presence in rice paddy soil pore water has recently been established. Thioarsenates are taken up by plants and show high mobility within plants. They are efficiently translocated from roots to shoots and can be loaded into grains. To date, however, no information is available on the transporter proteins enabling the necessary membrane passages. We tested the hypothesis that the major inorganic thioarsenate, monothioarsenate (MTA), is a substrate for phosphate transporters in experiments with yeast and plant model systems. Short-term uptake assays demonstrated MTA transport, albeit at much lower rates than apparent for arsenate. Plant mutants with defects in phosphate transporters or regulators controlling phosphate deficiency responses were more tolerant to MTA as indicated by growth phenotypes and pigment concentrations. High external phosphate supply suppressed the MTA effects. Also, the mutants accumulated less As in roots and shoots upon MTA exposure. Inside plants, MTA was efficiently converted into arsenite and activated the phytochelatin pathway. Nonetheless, in light of the much lower relative uptake rate for MTA, we hypothesize that this As species exerts specific toxicity effects.

The MYB family has been extensively studied in model organisms, but research on these transcription factors in vegetable crops such as cabbage (Brassica oleracea L. var. capitata L.) remains incomplete. We cloned BoMYB2 and determined its role in cabbage drought response. We found that overexpression of BoMYB2, which is induced by ABA, significantly enhanced cabbage tolerance to drought, whereas BoMYB2-silenced line displayed the opposite phenotype. Two proteins that interact with BoMYB2, BoMYC2 and BoAREB1, were verified by yeast two-hybrid, luciferase complementation, pull-down assays. Overexpression of these genes in Arabidopsis thaliana significantly improved drought tolerance in A. thaliana, while their transient silencing in cabbage seedlings reduced drought tolerance. Both proteins are also induced by ABA, and they cooperate with BoMYB2 to enhance plant antioxidant capacity under drought, modulate downstream gene expression, and increase plant survival during water deficit. In summary, our results indicate that BoMYB2-BoMYC2 and BoMYB2-BoAREB1 complexes play important roles in ABA-signal-mediated regulation of drought responses in cabbage.

Chickpea, a predominantly winter-season crop, is highly susceptible to drought stress during its reproductive stage, often resulting in substantial yield losses. To address this challenge, we tested the hypothesis that seeds developed under high-temperature conditions in the summer can enhance drought tolerance in progeny plants. This study evaluated the effects of seed development environment-summer-season seeds (SS) versus normal/winter-season seeds (NS)-on the morphological, physiological, biochemical and yield responses of chickpea under water-deficit stress (WDS). Genotype-specific performance was assessed across two seasons using seeds harvested from SS and NS environments. Progeny plants derived from SS exhibited significant improvements in key physiological traits, including increased relative water content (14%-16%), membrane stability index (6%-45%) and pollen viability (8%-13%) over NS-derived plants. Notably, SS-derived plants achieved yield advantages of up to 16% and 32% over NS-derived plants in the first and second seasons, respectively. Biochemical analyses further revealed enhanced antioxidant defence mechanisms in SS-derived plants, with increased activities of catalase (39%-50%) and peroxidase (33%), along with increased chlorophyll (44%-72%) and carotenoid (28%-32%) contents over NS-derived plants, indicating improved protection against oxidative stress. In addition, greater proline accumulation (15%-58%) and enhanced Photosystem II efficiency (7%-11%) were recorded in SS-derived plants over NS-derived plants, reflecting superior adaptive responses to drought stress. Genotype-specific differences were evident, with ICCV191218 and ICCV191229 consistently exhibiting superior performance and yield stability, and ICCV191218 was identified as the most stable across environments. These results demonstrate that exposure to high temperatures during seed development induces transgenerational tolerance to drought stress. The use of summer-developed seeds thus represents a low-cost, field-based strategy to enhance drought tolerance and yield stability in chickpea, offering a promising approach for improving crop adaptation in water-limited agroecologies.

In rice, some varieties exhibit high resistance to planthoppers. However, the mechanisms underlying this superior resistance remain largely unknown. Here, we found that compared to the variety Yuefeng (YF), brown planthopper (BPH, Nilaparvata lugens) exhibited significantly less feeding and weight gain, slower development, and lower survival rate and fecundity on the variety JN08. JN08 plants had higher phosphorylation levels of constitutive and BPH-induced mitogen-activated protein kinase (MPK) 4 and 6 than YF plants. They also showed quicker and stronger jasmonic acid (JA) and jasmonoyl-isoleucine response to BPH at early stages of infestation as well as higher constitutive and/or BPH-elicited levels of H₂O₂, most tested phenolamides and some tested flavonoids than YF plants. Bioassays showed that four of phenylamides, N-cinnamoylputrescine, N-p-coumaroylagmatine, N-p-coumaroyl-N'-feruloylputrescine and N-feruloyltyramine, all of which had higher levels in JN08 plant than YF plants, had a significant effect on the survival and/or growth of BPH nymphs. Moreover, overexpressing OsPAL1 (phenylalanine ammonia-lyase1), a gene encoding a rate-limiting enzyme in the phenylpropanoid biosynthesis pathway, in rice significantly reduced BPH performance. These results demonstrate that phenylpropanoid-associated metabolites, such as phenylamides and flavonoids, probably regulated by OsMPK4/6-mediated JA and H₂O₂ signalling pathways, play an important role in regulating rice resistance to BPH.