Jiangsu Provincial Key Laboratory of Crop Genetics and Physiology, Yangzhou University, Yangzhou, 225009, China.
Guizhou Rapeseed Institute, Guizhou Academy of Agricultural Sciences, Guiyang, 550008, China.
Plant Cell Rep. 2019 May;38(5):545-558. doi: 10.1007/s00299-019-02385-2. Epub 2019 Jan 31.
Abnormal tapetum degradation and anther development in cytoplasmic male sterility SaNa-1A are the main reasons for the anther abortion. SaNa-1A is a novel cytoplasmic male sterility (CMS) line of Brassica napus derived from somatic hybrids of B. napus-Sinapis alba, and SaNa-1B is the corresponding maintainer line. Ultrastructural comparison between developing anthers of sterile and maintainer lines revealed abnormal subcellular structure of pollen mother cells (PMCs) in the CMS line. The PMC volume and size of nucleus and nucleolus in the CMS line were smaller than those in the maintainer line. The abnormal tapetum cell development and delayed tapetum degradation inhibited microspore development. Finally, anther abortion in the CMS line occurred. Physiological and biochemical analyses of developing anthers and mitochondria revealed that over-accumulation of reactive oxygen species (ROS) in the SaNa-1A and deficiency in antioxidant enzyme system aggravated the oxidization of membrane lipids, resulting in malondialdehyde (MDA) accumulation in anthers. High MDA content in the CMS line was toxic to the cells. ROS accumulation in SaNa-1A also affected anther development. Abnormal structure and function of terminal oxidase, which participates in the electron transport chain of mitochondrial membrane, were observed and affected the activity of cytochrome c oxidase and FF-ATPase, which inhibited ATP biosynthesis. Proline deficiency in SaNa-1A also affected anther development. Few hybridization signals of programmed cell death (PCD) in tetrads of SaNa-1A were identified using TdT-mediated dUTP Nick-End Labeling assay. PCD was not obvious in tapetum cells of SaNa-1A until the unicellular stage. These results validated the cytological differences mentioned above, and proved that abnormal tapetum degradation and anther development in SaNa-1A were the main reasons for the anther abortion.
异常的绒毡层降解和花药发育是雄性不育 SaNa-1A 花药败育的主要原因。SaNa-1A 是一种新型甘蓝型油菜细胞质雄性不育（CMS）系，来源于甘蓝型油菜-白芥体细胞杂种，SaNa-1B 是其对应的保持系。不育系和保持系发育花药的超微结构比较表明，CMS 系花粉母细胞（PMC）的亚细胞结构异常。CMS 系 PMC 体积和核及核仁大小均小于保持系。绒毡层细胞发育异常和降解延迟抑制了小孢子发育，最终导致 CMS 系花药败育。发育中花药的生理生化分析和线粒体表明，SaNa-1A 中活性氧（ROS）的过度积累和抗氧化酶系统的缺乏加剧了膜脂的氧化，导致花药中丙二醛（MDA）的积累。CMS 系中高 MDA 含量对细胞有毒害作用。SaNa-1A 中 ROS 的积累也影响花药发育。参与线粒体膜电子传递链的末端氧化酶的异常结构和功能，影响细胞色素 c 氧化酶和 FF-ATPase 的活性，从而抑制 ATP 的合成。SaNa-1A 中脯氨酸的缺乏也影响花药发育。使用 TdT 介导的 dUTP 缺口末端标记法（TUNEL）在 SaNa-1A 的四分体中鉴定到很少的程序性细胞死亡（PCD）杂交信号。在 SaNa-1A 的绒毡层细胞中，PCD 直到单核期才变得明显。这些结果验证了上述细胞学差异，并证明 SaNa-1A 中异常的绒毡层降解和花药发育是花药败育的主要原因。
