Plant Physiology and Biochemistry最新文献

Oats (Avena sativa L.) are generally considered tolerant to unfavorable environmental conditions, although drought is known to impose yield losses. Several breeding programs worldwide aim at producing new oat genotypes tolerant to water deficit, but the molecular mechanisms underlying drought responses remain scarcely characterized. We investigated the growth and biomass production of 12 oat genotypes submitted to dehydration induced by PEG. Shoot elongation and biomass production were severely impaired by osmotic stress, whereas in roots growth and dry weight were mostly increased. To gain further insight into the responses, seedlings from 'URS Altiva' were subjected to osmotic stress for seven days, their growth and biomass performance investigated, and the transcriptome was determined for the shoots and roots of control and water-stressed plants. Distinct transcriptional programs were demonstrated to control dehydration responses in shoots and roots, agreeing with the phenotypic responses. Photosynthesis and chloroplast assembly pathways were negatively affected in the shoots, whereas in the roots the transcription of defense genes was mostly impaired. The salvage pathways induced by osmotic stress in oat shoots and roots were shared, consisting of water deprivation and abscisic acid-mediated pathways. Candidate genes and transcription factors regulating these pathways in response to dehydration were identified. Three modules of co-regulated genes were demonstrated to be correlated with biomass production in the shoots and roots and shoot elongation. This work contributes to the current understanding of the molecular mechanisms underlying the differential response of shoots and roots to dehydration and may provide tools to develop new tolerant cultivars.

Drought stress is a major constraint on the productivity of temperate forage grasses such as perennial ryegrass (Lolium perenne). While nitrogen management is widely employed in agronomic practice, its specific role in mediating drought adaptation strategies remains unclear. This study aimed to systematically characterize the response of perennial ryegrass to drought stress following low nitrogen pre-acclimation through integrated physiological and transcriptomic analyses during both stress and recovery phases. Our results demonstrated that drought severely impaired photosynthetic capacity and induced oxidative damage in non-acclimated plants, as evidenced by the significant reductions in net photosynthetic rate, stomatal conductance and PSII efficiency (Fv/Fm), alongside elevated malondialdehyde (MDA) levels and increased activities of key antioxidant enzymes (e.g., ascorbate peroxidase, peroxidase and catalase). In contrast, low nitrogen pre-acclimation effectively preserved photosynthetic performance under subsequent drought, mitigating declines in gas exchange parameters and maintaining PSII integrity. These pre-acclimated plants also exhibited reduced oxidative stress under drought and superior recovery capacity after rewatering. This enhanced drought tolerance was associated with fructan accumulation and tempered transcriptional responses. Low nitrogen pre-acclimation mitigated the drought-induced transcriptional upheaval, attenuated the activation of hormonal signaling pathways and MAPK cascades, significantly alleviated the downregulation of genes encoding photosynthetic apparatus, stabilized chlorophyll metabolism and optimized carbon-nitrogen balance. These findings reveal a nitrogen-mediated priming mechanism that enhances drought tolerance through integrated metabolic and transcriptional adjustments, providing new insights into the interaction between nutrient signaling and stress resistance, as well as potential strategies for enhancing plant tolerance under climate change.

Chloroplasts require a significant amount of iron to build up the photosynthetic apparatus. Upon developmental senescence, chloroplasts iron is subjected to remobilisation. Processes that enable iron removal from the chloroplasts have not been clarified in detail yet. Ferritins are primary iron storage proteins. Although chloroplast ferritins accumulate, in part during leaf senescence, their role in the removal of chloroplast iron has not been revealed in detail yet. Using Arabidopsis thaliana Col-0 model, we have studied the accumulation and the form of iron at the initiation and the progressing of senescence. Senescence status was characterised by the expression of Oresara 1 and Senescence Associated Gene 12. Physiological parameters, iron content and localization together with transcript abundance information were collected from the same leaf individuals. At senescence initiation, the accumulation of iron in the chloroplasts together with Ferritin transcripts and (apo)proteins rose, whereas under progressing senescence, chloroplast iron accumulation decreased. Low-energy X-ray fluorescence microscopy confirmed this increase in the iron signal at chloroplast sites. Ferritin signal in ⁵⁷Fe Mössbauer spectra (indicator of the major iron species population) was absent. Together with the stochastic presence of ferritin particles in chloroplasts this suggest that iron accumulation is a transient event involved in the iron remobilisation. Thus, ferritins do not serve as permanent storages, rather carriers that deliver iron for recycling during developmental senescence.

Nitrogen (N) limitation significantly constrains crop growth, yield and quality. Developing crop varieties with high N deficiency tolerance represents a critical strategy for reducing N fertilizer application and promoting sustainable agriculture. Semi-wild soybean offers valuable genetic resources for the improvement of soybean varieties. Nevertheless, the mechanisms underlying N deficiency tolerance remain poorly understood. In this study, we employed a comprehensive analytical approach-including Pearson's correlation analysis, principal component analysis, subordinate function analysis, and cluster analysis-to evaluate the N starvation tolerance of 50 semi-wild soybean varieties. Shoot fresh weight, root-shoot ratio, SPAD2 value and leaf nitrate content were identified as key indicators for assessing N starvation tolerance. The variety V03 was identified as the most N starvation-tolerant. Comparative physiological analyses revealed that V03 enhances tolerance to N deficiency by optimizing root architecture and sustaining the activity of nitrogen metabolism enzymes-such as nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT)-in root and leaf tissues. Transcriptomic analysis indicated that V03 exhibits a broader transcriptional response (with more N Starvation-induced DEGs) and functional reprogramming in root tissues, showing stronger enrichment in stress-responsive processes, regulatory functions, and plasma membrane-related terms as well as environmental information processing pathways. Furthermore, V03 displayed more pronounced changes in the expression of genes related to N transport, N assimilation and transcription factor (TF) compared to the N starvation-sensitive variety V46. This study provides a robust and comprehensive methodology for evaluating N deficiency tolerance in semi-wild soybean. Our findings offer new insights into the physiological adaptions and molecular regulatory network governing N uptake and metabolism, which may support future breeding efforts aimed at enhancing NUE in leguminous crops.

Medicago sativa (alfalfa), a vital perennial leguminous forage with economic and nutritional significance, is severely limited by drought stress. AP2/ERF transcription factors act as core modulators of plant responses to abiotic stresses. To improve alfalfa drought resistance, the MfERF053 gene cloned from Medicago falcata was introduced into the alfalfa genome. Its function and regulatory mechanism in alfalfa drought adaptation were investigated. We hypothesized that MfERF053 plays a pivotal role in drought resistance. Transgenic alfalfa lines overexpressing MfERF053 (OE) and ERF053 RNA interference (RNAi)-mediated alfalfa lines were developed. Drought resistance of OE, RNAi, and wild-type (WT) plants was assessed, alongside physiological phenotyping and RNA-seq profiling. The findings demonstrated that MfERF053 boosted alfalfa drought resistance. Specifically, OE lines exhibited a higher survival rate (68.05% vs. 12.96% in RNAi lines) and stronger water retention (29.45% leaf relative water content vs. 7.87% in RNAi lines). Their catalase and ascorbate peroxidase activities were also elevated, reactive oxygen species (ROS) accumulation was reduced, and photosynthetic function was stabilized (mitigated chlorophyll degradation and maintained PSII efficiency). RNA-seq analysis indicated that differentially expressed genes (DEGs) in OE plants were concentrated in three key pathways: abscisic acid (ABA) signaling, antioxidant defense, and photosynthetic pathways. Additionally, these DEGs synergistically regulate key genes within these pathways. This study verified the function of MfERF053 in drought resistance through multiple regulatory pathways. Furthermore, it provides novel insights into ERF-mediated drought resistance in alfalfa and offers a valuable molecular candidate for breeding drought-tolerant alfalfa varieties.

Aerated irrigation alleviates the high soil saturation issue caused by conventional irrigation by delivering oxygen-enriched water to the crop root zone. However, whether it can alleviate plant hypoxia under waterlogging stress remains unclear. In this study, we examined the effects of aeration on the growth, photosynthetic physiological activities, and gene expression of lettuce (Lactuca sativa L.) under different waterlogging durations (0, 4, and 8 days). The results indicate that under short-term waterlogging stress (≤4d), plants reduce the accumulation of reactive oxygen species by increasing the activity of the antioxidant system, and aeration does not significantly enhance plant growth. If waterlogging lasts for more than 8 days, non-aerated treatment leads to significant accumulation of reactive oxygen species (O₂^- and H₂O₂ increased by 50.68% and 37.76%, respectively), cell membrane damage (MDA increased by 32.31%), and damage to the photosynthetic system. At this point, aerated irrigation can significantly alleviate stress by increasing the expression of Psb and rbcS genes in leaves, maintaining normal photosynthetic function of lettuce, and increasing lettuce biomass by 36.70% compared to non-aerated treatment. Therefore, in actual waterlogging event management, aeration irrigation should be prioritized for long-term waterlogging (8d) areas. Twelve gene co-expression modules were identified using the weighted gene co-expression network analysis (WGCNA) method. Three modules specifically related to lettuce waterlogging stress were identified through correlation analysis with physiological indicators. The five hub genes (HPR3, GGPS1, THI1, rbcS, G6PD) in the yellow module have become sensitive genes that lead to a decrease in photosynthetic efficiency under waterlogging stress. The hub genes of brown and green modules (PPC4, FRO7, ispH, ERF1b, AUF2) showed an increase in expression levels with the passage of waterlogging time. These five genes may be the core genes for improving lettuce waterlogging tolerance. This study explored the molecular mechanism of lettuce's tolerance to waterlogging stress at the transcriptome level, providing deeper insights into the alleviating effect of aerated irrigation on waterlogging stress.

Benzylisoquinoline alkaloids (BIAs) are a notable class of bioactive natural products with therapeutic potential. Metabolomic profiling identified a total of 186 BIAs across various tissues of Eomecon chionantha, with sanguinarine and chelerythrine being the predominant compounds, quantified at 5.2 mg/g and 9.9 mg/g in the roots, respectively. The biosynthetic pathways for these compounds have been elucidated in species of the Papaveraceae family, where methylation events are crucial. Here, we present a telomere-to-telomere (T2T) gap-free genome assembly of E. chionantha, which has a total size of 368.5 Mb, comprising nine centromeric regions, 15 telomeres, 19,785 protein-coding genes, and 58.89% repetitive sequences. Genome analysis reveals a single whole-genome duplication in E. chionantha predating its divergence from Macleaya cordata (∼37.9 million years ago). Gene family analysis revealed the presence of 28 O-methyltransferase (OMT) genes in the E. chionantha genome, predominantly amplified through tandem duplication events, as well as the screening of EcOMT3/4/5/10/17/25/26/27 may be involved in the biosynthesis of sanguinarine and chelerythrine. Functional characterization demonstrated that all eight EcOMTs exhibit activity as 6OMT and scoulerine-9-O-methyltransferase (SMT), with only EcOMT17 functioning specifically as a 4'OMT, indicating that multiple EcOMTs have the catalytic capacity for 6OMT and SMT functions, while 4'OMT activity is highly specific. Collectively, this work elucidates OMT roles in BIA biosynthesis while offering genomic resources for Papaveraceae research and evolutionary insights into alkaloid diversification.