The high fat content in oat seeds makes them susceptible to aging during storage, leading to reduced seed vigor, delayed germination, and even seed death. Much evidence suggests that lipid remodeling is closely associated with successful seed germination. However, the dynamic behavior and response mechanisms of lipids during the germination of aged oat seeds remain unclear. In this study, ‘Monida’ (aging-tolerant) and ‘Haywire’ (aging-sensitive), were used to investigate the lipid profiles in the embryo and endosperm and the dynamic transcriptomic differences in the embryo during the germination. The results demonstrate that phospholipid alterations during the germination of aged seeds are more significant compared to unaged seeds, indicating that aging affects lipid remodeling during germination, particularly in the ‘Haywire’. Further analysis revealed that the most critical lipid response events occurred at the end of germination stage II (32 h) in embryo, primarily regulated through the PLC-DGK pathway to modulate phospholipid and glycerolipid molecules. Specifically, transcripts of PLC, DGK, and DGAT were upregulated, promoting the generation of diacylglycerol (DG) from various phospholipids, which further increased the monogalactosyldiacylglycerol/digalactosyldiacylglycerol (MGDG/DGDG) ratio, thereby influencing membrane repair. Additionally, at 6 h of germination in aged seeds, PC(3:0/0:0) levels significantly decreased. Compared to ‘Monida,’ the aging-sensitive ‘Haywire’ seeds exhibited substantial production of PE(19:0/0:0) and PC(15:0/0:0) at 32 h of germination, which may be key factors contributing to the seed's sensitivity to aging and the significant reduction in germination percentage after aging. Therefore, PC(3:0/0:0), PE(19:0/0:0), and PC(15:0/0:0) could serve as important lipid metabolic markers in future studies on the mechanisms of oat seed vigor. The findings of this study provide insights into the specificity of lipid remodeling and its response mechanisms during the germination of aged oat seeds, providing a theoretical foundation for the safe preservation of oat germplasm and the development of aging-tolerant varieties.

Alfalfa (Medicago sativa L.), a high-quality perennial legume forage, is pivotal in global animal husbandry and ecological systems. However, its growth and production are threatened by various abiotic stresses, including drought, salinity, low temperatures, and heavy metal toxicity. This review summarizes recent research on the molecular mechanisms underlying alfalfa’s responses to these environmental adversities. It provides a theoretical foundation for enhancing the stress resistance of alfalfa, offering a valuable reference for breeding high-quality, stress-resistant alfalfa varieties.

Drought stress affects plant photosynthesis, leading to a reduction in the quality and yield of crop production. Non-foliar organs play a complementary role in photosynthesis during plant growth and development and are important sources of energy. However, there are limited studies on the performance of non-foliar organs under drought stress. The photosynthetic-responsive differences of oat spikelet organs (glumes, lemmas and paleas) and flag leaves to drought stress during the grain-filling stage were examined. Under drought stress, photosynthetic performance of glume is more stable. Intercellular CO2 concentration (Ci), chlorophyll b, maximum photochemical efficiency of photosystem II. (Fv/Fm), and electron transport rate (ETR) were significantly higher in the glume compared to the flag leaf. The transcriptome data revealed that stable expression of the RCCR gene under drought stress was the main reason for maintaining higher chlorophyll content in the glume. Additionally, no differential expression genes (DEGs) related to Photosystem Ⅰ (PSI) reaction centers were found, and drought stress primarily affects the Photosystem II (PSII) reaction center. In spikelets, the CP43 and CP47 subunits of PSII and the AtpB subunit of ATP synthase were increased on the thylakoid membrane, contributing to photosynthetic stabilisation of spikelets as a means of supplementing the limited photosynthesis of the leaves under drought stress. The results enhanced understanding of the photosynthetic performance of oat spikelet during the grain-filling stage, and also provided an important basis on improving the photosynthetic capacity of non-foliar organs for the selection and breeding new oat varieties with high yield and better drought resistance.

BACKGROUND:Medicago sativa, often referred to as the "king of forage", is prized for its high content of protein, minerals, carbohydrates, and digestible nutrients. However, various abiotic stresses can hinder its growth and development, ultimately resulting in reduced yield and quality, including water deficiency, high salinity, and low temperature. The ethylene-insensitive 3 (EIN3)/ethylene-insensitive 3-like (EIL) transcription factors are key regulators in the ethylene signaling pathway in plants, playing crucial roles in development and in the response to abiotic stresses. Research on the EIN3/EIL gene family has been reported for several species, but minimal information is available for M. sativa. RESULTS:In this study, we identified 10 MsEIN3/EIL genes from the M. sativa genome (cv. Zhongmu No.1), which were classified into three clades based on phylogenetic analysis. The conserved structural domains of the MsEIN3/EIL genes include motifs 1, 2, 3, 4, and 9. Gene duplication analyses suggest that segmental duplication (SD) has played a significant role in the expansion of the MsEIN3/EIL gene family throughout evolution. Analysis of the cis-acting elements in the promoters of MsEIN3/EIL genes indicates their potential to respond to various hormones and environmental stresses. We conducted a further analysis of the tissue-specific expression of the MsEIN3/EIL genes and assessed the gene expression profiles of MsEIN3/EIL under various stresses using transcriptome data, including cold, drought, salt and abscisic acid treatments. The results showed that MsEIL1, MsEIL4, and MsEIL5 may act as positive regulatory factors involved in M. sativa's response to abiotic stress, providing important genetic resources for molecular design breeding. CONCLUSION:This study investigated MsEIN3/EIL genes in M. sativa and identified three candidate transcription factors involved in the regulation of abiotic stresses. These findings will offer valuable insights into uncovering the molecular mechanisms underlying various stress responses in M. sativa.

Plants must cope with diverse environmental stresses during growth and development, among which drought is one of the most concerning global threats. Recent studies have shown that the disassembly of the microtubule cytoskeleton plays an essential role during ABA-induced stomatal closure in response to drought stress. To facilitate studies on the mechanisms of ABA-induced microtubule rearrangement during stomatal closure, we describe procedures for observing guard cells treated with ABA, visualizing the microtubule cytoskeleton in guard cells, and their subsequent quantitative analysis. We include both representative images and the quantification results to illustrate these experiments.

Drought stress triggers abscisic acid (ABA) signaling in guard cells and induces stomatal closure to prevent water loss in land plants. Stomatal movement is accompanied by reorganization of the cytoskeleton. Cortical microtubules disassemble in response to ABA, which is required for stomatal closure. However, how ABA signaling regulates microtubule disassembly is unclear, and the microtubule-associated proteins (MAPs) involved in this process remain to be identified. In this study, we show that OPEN STOMATA 1 (OST1), a central component in ABA signaling, mediates microtubule disassembly during ABA-induced stomatal closure in Arabidopsis thaliana. We identified the MAP SPIRAL1 (SPR1) as the substrate of OST1. OST1 interacts with and phosphorylates SPR1 at Ser6, which promotes the disassociation of SPR1 from microtubules and facilitates microtubule disassembly. Compared with the wild type, the spr1 mutant exhibited significantly greater water loss and reduced ABA responses, including stomatal closure and microtubule disassembly in guard cells. These phenotypes were restored by introducing the phosphorylated active form of SPR1. Our findings demonstrate that SPR1 positively regulates microtubule disassembly during ABA-induced stomatal closure, which depends on OST1-mediated phosphorylation. These findings reveal a specific connection between a core component of ABA signaling and MAPs.

Germination of aged seeds may be associated with specific metabolic changes. The objective of this study was to examine physiological and metabolic alterations before and after germination of control and aged oat (Avena sativa) seeds. The activity of antioxidant enzymes and the level of storage compounds were measured in the embryo and endosperm at 0, 4, 16, and 32 h of imbibition for control seeds and 0, 4, 16, 32, and 60 h of imbibition for medium vigor seeds after artificially accelerated aging; metabolomic changes were determined in embryos at 16 and 32 h of seed imbibition. In aged oat seeds, superoxide dismutase activity and catalase activity increased in the late imbibition stage. The content of soluble sugars decreased significantly in the later stages of imbibition, while the content of proteins increased in 32 h of seed imbibition eventually producing mannitol and proline. The mobilization of fat in deteriorated seeds was mainly through the sphingolipid metabolic pathway generated by cell growth-promoting dihydrosphingosine-1-phosphate. Ascorbic acid, avenanthramide and proline levels increased significantly at 60 h of imbibition, playing an important role in the germination of aged oat seeds.

种子使植物能够在恶劣的环境条件下生存,将遗传信息从亲代传递给下一代.种子活力是农业中的一个重要性状,直接影响田间出苗率和作物产量.然而,由于种子老化,种子活力在贮藏过程中下降.为了有效地保护基因资源,减少由于种子老化给农业生产带来的巨大经济损失,有必要探究种子老化的机制,以便了解种子老化的起因以及老化过程中发生的一系列重要事件.在种子贮藏过程中,高温高湿是加速种子老化的两个主要因素.活性氧(ROS)引起的氧化损伤是主要原因.ROS可导致蛋白质损伤、脂质过氧化、染色体端粒结构异常和DNA损伤引起的各种细胞成分损伤.此外,ROS还诱导细胞程序性死亡,导致种子老化.种子在吸胀初期会对一些损伤进行修复,但是,如果对关键结构造成巨大损伤,就会导致修复失败,种子永久失去活力,无法在相对较短的时间内正常发芽.种子老化的确切机制尚未得到全面研究.基于此,本研究主要综述了种子老化过程中ROS的产生以及清除途径、ROS对生物大分子的影响、染色体端粒系统对种子老化的响应以及种子耐老化相关基因的研究进展,并提出了展望.这对了解种子老化的原因以及种子老化机制的解析具有重要意义.

气孔是植物响应外源信号,与环境进行水分和气体交换的门户.由外源信号引起的保卫细胞微丝骨架动态变化在气孔运动中发挥重要作用,但是具体的精确调节机制仍不清楚.微丝结合蛋白家族(ABPs)是微丝动态组装最直接的调控者,它们的作用不容忽视.本文运用反向遗传学,以微丝结合蛋白—加帽蛋白(CP)β-亚基(CPB)突变体cpb-3为实验材料,探究其在壳梭孢素(FC)诱导气孔开放中的作用.结果发现:离体叶片干燥3 h,cpb-3突变体的叶片失水率为63.45％,明显高于野生型的48.99％.气孔开度测量及激光共聚焦显微镜观察发现,cpb-3突变体的气孔开放程度以及微丝动态重排对FC分子更敏感.气孔开度相比野生型增大了 20％(P＜0.05),含辐射状微丝排布的保卫细胞数量比例增幅达到58.3％,比对照组高出18.5％.此外,非损伤微测技术记录保卫细胞Ca2+、K+等跨膜运输动态,FC处理下,cpb-3突变体保卫细胞中Ca2+外流速度升至212.86 pmol cm-2ss-1,野生型仅为68.76 pmol cm-2s-1,明显快于野生型.且K+内流也有相同表现.综上表明,微丝加帽蛋白CP的β亚基CPB可能通过调节保卫细胞微丝骨架动态重排以及离子流动,在FC诱导的气孔运动中发挥重要的作用.

Regulation of stomatal movement is critical for plant adaptation to environmental stresses. The microtubule cytoskeleton undergoes disassembly, which is critical for stomatal closure in response to abscisic acid (ABA). However, the mechanism underlying this regulation largely remains unclear. Here we show that a ubiquitin-26S proteasome (UPS)-dependent pathway mediates microtubule disassembly and is required for ABA-induced stomatal closure. Moreover, we identify and characterize the ubiquitin E3 ligase MREL57 (MICROTUBULE-RELATED E3 LIGASE57) and the microtubule-stabilizing protein WDL7 (WAVE-DAMPENED2-LIKE7) in Arabidopsis and show that the MREL57-WDL7 module regulates microtubule disassembly to mediate stomatal closure in response to drought stress and ABA treatment. MREL57 interacts with, ubiquitinates and degrades WDL7, and this effect is clearly enhanced by ABA. ABA-induced stomatal closure and microtubule disassembly are significantly suppressed in mrel57 mutants, and these phenotypes can be restored when WDL7 expression is decreased. Our results unravel UPS-dependent mechanisms and the role of an MREL57-WDL7 module in microtubule disassembly and stomatal closure in response to drought stress and ABA.

Regulation of cortical microtubule reorganization is essential for plant cell survival under high salinity conditions. In response to salt stress, microtubules undergo rapid depolymerization followed by reassembly to form a new microtubule network that promotes cell survival; however, the upstream regulatory mechanisms for this recovery response are largely unknown. In this study, we demonstrate that ethylene signaling facilitates salt stress-induced reassembly of cortical microtubules in Arabidopsis (Arabidopsis thaliana). Microtubule depolymerization was not affected under salt stress following the suppression of ethylene signaling with Ag+ or in ethylene-insensitive mutants, whereas microtubule reassembly was significantly inhibited. ETHYLENE-INSENSITIVE3, a key transcription factor in the ethylene signaling pathway, was shown to play a central role in microtubule reassembly under salt stress. In addition, we performed functional characterization of the microtubule-stabilizing protein WAVE-DAMPENED2-LIKE5 (WDL5), which was found to promote ethylene-associated microtubule reassembly and plant salt stress tolerance. These findings indicate that ethylene signaling regulates microtubule reassembly by up-regulating WDL5 expression in response to salt stress, thereby implicating ethylene signaling in salt-stress tolerance in plants.

Proper regulation of seed germination is essential for the successful propagation of a plant. The transcription factor ABSCISIC ACID INSENSITIVE5 (ABI5) of the abscisic acid (ABA) signaling pathway plays a central role in the inhibition of seed germination. ABI5 is precisely regulated by the core ABA signaling components and multiple other factors. However, the complex regulatory network of ABI5 remains largely unknown. In this study, we determined the biochemical interaction between ABI5 and the BRINSENSITIVE1 (BRI1)-EMS-SUPPRESSOR1 (BES1) transcription factor of the brassinosteroid (BR) signaling pathway, as well as the function of BES1 regulating ABI5 during seed germination in Arabidopsis. BES1 directly interacts with ABI5 both in vitro and in vivo. The bZIP domain of ABI5, which is responsible for DNA binding, is critical for ABI5 binding to BES1. The interaction of BES1 with ABI5 significantly suppressed the binding of ABI5 to the promoter regions of downstream genes, which resulted in their reduced expression and consequently facilitated seed germination. This study shed new light on the coordination of multiple signaling pathways during seed germination. In particular, BES1 directly binds to ABI5, which interferes with its transcriptional activity and suppresses ABA signaling output.