玉米核雄性不育基因msg1的精细定位及其花药败育机理研究

Genic male sterility is a heritable phenomenon caused by mutated nuclear genes, resulting in male sterility but female fertility. Genic male sterility (‘ms’ for short) has long been overlooked due to limitations of its application in maize breeding. Only a few ms genes have been cloned in maize by now, however, these genes consistently cause abnormality in earlier stages of anther development. Due to the lack of ms mutants during later stages of anther development, none of ms genes of these stages have been cloned. Consequently, the molecular mechanisms for later stage sterility have not been revealed in maize so far. In the course of maize breeding, we identified a natural male sterile line msg1 showing normal anther development until the large vacuolated pollens arise. msg1 has the latest abortive stage among the ms mutants identified so far. We are aiming to fine map msg1 and identify candidate genes for msg1 based on the fine mapping data and gene expression data. The critical stages of msg1 sterility will be revealed through the cytological studies of msg1 and its near-isogenic line. We will also identify the key genes involved in anther development through RNA-Seq of the anthers of msg1 and its near-isogenic line. Finally, the mechanisms of msg1 anther sterility will be uncovered, which will provide some clues for deciphering the molecular mechanisms of pollen abortion during later stages of anther development in maize.

核雄性不育是由细胞核内基因突变导致的雄性败育但雌性可育的遗传现象。长期以来，由于核雄性不育系在玉米育种中的应用受限，玉米核雄性不育的研究没有受到重视。目前玉米中仅克隆到少数几个核不育基因，且这几个基因导致的雄性败育都发生在花药发育早期。由于玉米花药晚期败育突变体的缺失，至今尚未克隆到玉米花药晚期败育基因，花药晚期败育的分子机理也知之甚少。本课题组在玉米育种过程中筛选到一个自然雄性不育突变体msg1，其败育发生在小孢子大液泡化之后，是目前玉米中发现的败育时期最晚的核雄性不育系。本项目拟对msg1基因进行遗传作图和精细定位，结合基因表达数据和候选基因功能预测，锁定目的基因；并对msg1及其近等基因系的花药发育过程进行细胞学观察，确定msg1败育的关键时期；然后对败育关键时期的花药进行转录组测序，发掘花药发育关键基因，解析msg1花药败育机理，为揭示玉米花药晚期败育的分子机理提供依据。