BACKGROUND Photoperiod and/or thermo-sensitive male sterility is an effective pollination control system in crop two-line hybrid breeding. We previously discovered the spontaneous mutation of a partially male sterile plant and developed a thermo-sensitive genic male sterile (TGMS) line 373S in Brassica napus L. The present study characterized this TGMS line through cytological observation, photoperiod/ temperature treatments, and genetic investigation. RESULTS Microscopic observation revealed that the condensed cytoplasm and irregular exine of microspores and the abnormal degradation of tapetum are related to pollen abortion. Different temperature and photoperiod treatments in field and growth cabinet conditions indicated that the fertility alteration of 373S was mainly caused by temperature changes. The effects of photoperiod and interaction between temperature and photoperiod were insignificant. The critical temperature leading to fertility alteration ranged from 10 °C (15 °C/5 °C) to 12 °C (17 °C/7 °C), and the temperature-responding stage was coincident with anther development from pollen mother cell formation to meiosis stages. Genetic analysis indicated that the TGMS trait in 373S was controlled by one pair of genes, with male sterility as the recessive. Multiplex PCR analysis revealed that the cytoplasm of 373S is pol type. CONCLUSIONS Our study suggested that the 373S line in B. napus has a novel thermo-sensitive gene Bnmst1 in Pol CMS cytoplasm background, and its fertility alteration is mainly caused by temperature changes. Our results will broaden the TGMS resources and lay the foundation for two-line hybrid breeding in B. napus.

中文翻译：

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甘蓝型油菜热敏性雄性不育系373S花药结构的细胞学观察和遗传研究。

背景技术光周期和/或热敏雄性不育是作物两系杂交育种中的有效授粉控制系统。我们之前发现了部分不育植物的自发突变，并在甘蓝型油菜中开发了热敏性不育雄性不育系（TGMS）373S。本研究通过细胞学观察，光周期/温度处理和遗传研究对这种TGMS系进行了表征。结果显微镜观察发现，小孢子的胞浆浓缩和不规则外ine以及绒毡层的异常降解与花粉流产有关。田间和生长箱条件下不同的温度和光周期处理表明373S的肥力变化主要是由温度变化引起的。光周期以及温度和光周期之间的相互作用的影响不明显。导致生育力改变的临界温度范围从10°C（15°C / 5°C）到12°C（17°C / 7°C），并且温度响应阶段与花粉母细胞的花药发育同时发生形成到减数分裂阶段。遗传分析表明，373S的TGMS性状受一对基因控制，雄性不育为隐性。多重PCR分析显示373S的细胞质为pol型。结论我们的研究表明，甘蓝型油菜中的373S系在Pol CMS细胞质背景中具有一个新的热敏基因Bnmst1，其繁殖力的改变主要是由温度变化引起的。我们的研究结果将拓宽TGMS的资源，并为甘蓝型油菜两系杂交育种奠定基础。