Gao Chenhao, Qi Shuanghui, Liu Kaige, Li Dong, Jin Changyu, Duan Shaowei, Zhang Meng, Chen Mingxun
College of Agronomy, Northwest A&F University, Yangling, Shaanxi 712100, China.
College of Agronomy, Northwest A&F University, Yangling, Shaanxi 712100, China.
Biochem Biophys Res Commun. 2017 Apr 22;486(1):124-129. doi: 10.1016/j.bbrc.2017.03.011. Epub 2017 Mar 8.
Previous studies have shown that DNA topoisomerase Iα (AtTOP1α) has specific developmental functions during growth and development in Arabidopsis thaliana. However, little is known about the roles of DNA topoisomerases in the closely related and commercially important plant, rapeseed (Brassica napus). Here, the full-length BnTOP1α-1 coding sequence was cloned from the A2 subgenome of the Brassica napus inbred line L111. We determine that all BnTOP1α paralogs showed differing patterns of expression in different organs of L111, and that when expressed in tobacco leaves as a fusion protein with green fluorescent protein, BnTOP1α-1 localized to the nucleus. We further showed that ectopic expression of BnTOP1α-1 in the A. thaliana top1α-7 mutant fully complemented the early flowering phenotype of the mutant. Moreover, altered expression levels in top1α-7 seedlings of several key genes controlling flowering time were restored to wild type levels by ectopic expression of BnTOP1α-1. These results provide valuable insights into the roles of rapeseed DNA topoisomerases in flowering time, and provide a promising target for genetic manipulation of this commercially significant process in rapeseed.
先前的研究表明，DNA拓扑异构酶Iα（AtTOP1α）在拟南芥的生长发育过程中具有特定的发育功能。然而，对于与拟南芥亲缘关系密切且具有重要商业价值的植物油菜（甘蓝型油菜）中DNA拓扑异构酶的作用，人们却知之甚少。在此，从甘蓝型油菜自交系L111的A2亚基因组中克隆出了全长BnTOP1α-1编码序列。我们确定，所有BnTOP1α旁系同源基因在L111的不同器官中表现出不同的表达模式，并且当作为与绿色荧光蛋白的融合蛋白在烟草叶片中表达时，BnTOP1α-1定位于细胞核。我们进一步表明，BnTOP1α-1在拟南芥top1α-7突变体中的异位表达完全互补了该突变体的早花表型。此外，通过BnTOP1α-1的异位表达，控制开花时间的几个关键基因在top1α-7幼苗中的表达水平变化恢复到了野生型水平。这些结果为油菜DNA拓扑异构酶在开花时间方面的作用提供了有价值的见解，并为油菜这一具有重要商业意义的过程的遗传操作提供了一个有前景的靶点。
