Cao Ling, Wang Sheng, Zhao Lihua, Qin Yuan, Wang Hong, Cheng Yan
State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Center for Genomics and Biotechnology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
Plants (Basel). 2021 Nov 9;10(11):2418. doi: 10.3390/plants10112418.
Protein ubiquitination is important for the regulation of meiosis in eukaryotes, including plants. However, little is known about the involvement of E2 ubiquitin-conjugating enzymes in plant meiosis. Arabidopsis UBC22 is a unique E2 enzyme, able to catalyze the formation of ubiquitin dimers through lysine 11 (K11). Previous work has shown that mutants are defective in megasporogenesis, with most ovules having no or abnormally functioning megaspores; furthermore, some mutant plants show distinct phenotypes in vegetative growth. In this study, we showed that chromosome segregation and callose deposition were abnormal in mutant female meiosis while male meiosis was not affected. The meiotic recombinase DMC1, required for homologous chromosome recombination, showed a dispersed distribution in mutant female meiocytes compared to the presence of strong foci in WT female meiocytes. Based on an analysis of F1 plants produced from crosses using a mutant as the female parent, about 24% of female mutant gametes had an abnormal content of DNA, resulting in frequent aneuploids among the mutant plants. These results show that UBC22 is critical for normal chromosome segregation in female meiosis but not for male meiosis, and they provide important leads for studying the role of UBC22 and K11-linked ubiquitination.
蛋白质泛素化对于包括植物在内的真核生物减数分裂的调控至关重要。然而，关于E2泛素结合酶在植物减数分裂中的作用却知之甚少。拟南芥UBC22是一种独特的E2酶，能够通过赖氨酸11（K11）催化泛素二聚体的形成。先前的研究表明，突变体在大孢子发生过程中存在缺陷，大多数胚珠没有大孢子或大孢子功能异常；此外，一些突变植株在营养生长方面表现出明显的表型。在本研究中，我们发现突变体雌性减数分裂过程中染色体分离和胼胝质沉积异常，而雄性减数分裂未受影响。与野生型雌性减数分裂细胞中强烈的焦点存在相比，同源染色体重组所需的减数分裂重组酶DMC1在突变体雌性减数分裂细胞中呈分散分布。基于对以突变体为母本杂交产生的F1植株的分析，约24%的突变体雌性配子DNA含量异常，导致突变植株中频繁出现非整倍体。这些结果表明，UBC22对雌性减数分裂中正常的染色体分离至关重要，但对雄性减数分裂则不然，它们为研究UBC22和K11连接的泛素化作用提供了重要线索。
