种子脱水快、耐脱水是宜机收玉米品种的关键特性。在种子成熟过程中,ABA通过调控胁迫响应蛋白合成,促进种子脱水耐性形成。申请人发现,在玉米ABA缺失突变体vp5(脱水慢)种子中,多种LEA蛋白含量明显比野生型Vp5(脱水正常)种子中低,说明LEA蛋白的积累受ABA调控。但ABA调控LEA蛋白积累的机制并不十分清楚。本项目以vp5、Vp5种子为材料,分析种子发育过程中ABA含量的动态变化和脱水耐性获得的进程;在转录组和蛋白质组水平上系统研究成熟过程中LEA mRNA和蛋白的变化规律,分析LEA mRNA起始表达和LEA蛋白起始合成时ABA的阈值;通过离体、活体实验,验证ABA的效应;鉴定与种子脱水耐性相关的关键LEA蛋白,研究其组织、亚细胞定位,分析其行使功能的场所和转运途径。预期结果对于解析LEA蛋白积累的分子机制具有重要作用,为通过分子调控LEA蛋白合成培育耐脱水玉米品种提供依据。

Fast and high desiccation tolerance of maize seeds is vital to the mechanized harvesting of maize production. During maize seed maturation and desiccation, abscisic acid (ABA) promotes the formation of seed desiccation tolerance by regulating various protein syntheses, e.g. late embryogenesis abundant (LEA) proteins. In previous research, the applicant found that the accumulation patterns of LEA proteins in maize mutant vp5 seeds were much lower than that in wild-type Vp5. The mutant vp5 seeds contain much lower ABA amounts and display a slower desiccation during maturation compared to Vp5 seeds. However, it is largely unclear regarding the mechanism underlying the accumulation of LEA proteins regulated by ABA. In this proposed project, with vp5 and Vp5 seeds (embryos) at different stages as experimental materials, we will 1) analyze the dynamic changes of moisture and ABA content and their correlation during seed maturation; 2) find more LEA proteins/genes induced by ABA in seeds on the proteome and transcriptome levels; 3) determine the moisture and ABA thresholds for inducing the initiation of the synthesis of LEA proteins/genes; 4) study the change of LEA genes/proteins with the presence of exogenous ABA or its inhibitor; 5) determine the subcellular localization of these LEA proteins by immune electron microscopy. The expected results will play important roles in resolving the mechanism underlying the accumulation of LEA proteins regulated by ABA. The realization of this project will provide theoretical and applied basis for molecular breeding of maize cultivars with fast and high tolerance of seed dehydration.