玉米温敏不育相关基因ZmTMS5的功能研究及玉米新型温敏不育系的定向创制

Benefiting form significant heterosis, commercial hybrid maize is widely used. Producing hybrid maize seeds requires emasculation to prevent self-pollination. Nowadays, emasculation in hybrid maize seed production is still performed by hands or machines. This process is costly, inefficient, and is not easy to completely remove the functional pollen grains. Male sterility lines do not require emasculation and therefore are ideal female lines for hybrid seed production. Male sterility includes cytoplasmic male sterility (CMS) and genic male sterility (GMS). Cytoplasmic male sterility (CMS) was firstly used for hybrid maize. But In 1970s, the outbreak of corn southern leaf blight almost completely destroyed maize CMS-T lines in USA. And after that, CMS lines were rarely used. So, GMS lines, especially photoperiod-sensitive GMS (PGMS) lines and temperature-sensitive GMS (TGMS) lines, are in a great need for hybrid maize seed production. In a recent study, researchers found that mutation of thermosensitive genic male sterile 5 (tms5) in rice causes the TGMS trait in most GMS lines, which were widely utilized in hybrid rice seed production. Investigating the function of its homolog gene ZmTMS5 in maize might be able to help us to generate maize TGMS lines. In this project, using genome editing technology, we will create ZmTMS5 mutation in maize. Through the investigation of ZmTMS5 mutant lines, we attempt to answer three questions in this project. Firstly, Is ZmTMS5 mutation able to cause TGMS trait in maize? Secondly, does ZmTMS5 share conserved function with OsTMS5? Thirdly, does ZmTMS5 mutation have commercial value in maize genetic breeding?

由于玉米杂种优势显著，商用的玉米种子多数是杂交种。但玉米的杂交制种过程中普遍采用人工或机械去雄，费时费力且很难保证杂交种的纯度。将雄性不育系材料用于杂交制种，可能是解决这一问题的重要途径。雄性不育系分为胞质雄性不育系和核雄性不育系两大类。上世纪小斑病爆发造成T型胞质不育系材料的大面积受灾，所以胞质雄性不育系材料已很少用于玉米杂交制种。所以，我们急需研制出适用于生产的核雄性不育系材料。近期研究发现，水稻两系杂交育种中，多数常用的核雄性不育系材料的不育性状是由OsTMS5基因缺失突变造成的，所以在玉米中研究其同源基因ZmTMS5的功能将有助于我们创制玉米温敏雄性不育系材料。本项目拟通过基因组编辑技术在玉米基因组中定点突变ZmTMS5，完成以下三方面研究：①验证ZmTMS5突变体是否在高温下造成花粉败育；②解析ZmTMS5在玉米中的作用机理；③评估ZmTMS5突变体应用于玉米制种的可行性。

由于玉米杂种优势显著，商用的玉米种子多数是杂交种。但玉米的杂交制种过程中普遍采用人工或机械去雄，费时费力且很难保证杂交种的纯度。将雄性不育系材料用于杂交制种，可能是解决这一问题的重要途径。水稻两系杂交育种中，多数常用的核雄性不育系材料的不育性状是由OsTMS5基因缺失突变造成的，所以在玉米中研究其同源基因ZmTMS5的功能将有助于我们创制玉米温敏雄性不育系材料。本项目通过基因组编辑技术对玉米基因组中ZmTMS5进行了定点突变。观察发现，敲除ZmTMS5仅仅影响玉米花粉的发育及花粉的传播，表现为高温下，花粉不育，不易散粉；但是对玉米其他器官的发育，尤其是雌穗的发育及育性。上述实验证明，敲除ZmTMS5能够创制玉米温敏不育材料，该材料在玉米杂交育种发面具备潜在的应用价值。