FT-like proteins induce transposon silencing in the shoot apex during floral induction in rice

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Shojiro Tamaki, Hiroyuki Tsuji, Ayana Matsumoto, Akiko Fujita, Zenpei Shimatani, Rie Terada, Tomoaki Sakamoto, Tetsuya Kurata, Ko Shimamoto
Proceedings of the National Academy of Sciences, 2015, 112(8): E901-E910  DOI: 10.1073/pnas.1417623112;      追溯原文......本站官方QQ群:62473826

Floral induction is a crucial developmental step in higher plants. Florigen, a mobile floral activator that is synthesized in the leaf and transported to the shoot apex, was recently identified as a protein encoded by FLOWERING LOCUS T (FT) and its orthologs; the rice florigen is Heading date 3a (Hd3a) protein. The 14-3-3 proteins mediate the interaction of Hd3a with the transcription factor OsFD1 to form a ternary structure called the florigen activation complex on the promoter of OsMADS15, a rice APETALA1 ortholog. However, crucial information, including the spatiotemporal overlap among FT-like proteins and the components of florigen activation complex and downstream genes, remains unclear. Here, we confirm that Hd3a coexists, in the same regions of the rice shoot apex, with the other components of the florigen activation complex and its transcriptional targets. Unexpectedly, however, RNA-sequencing analysis of shoot apex from wild-type and RNA-interference plants depleted of florigen activity revealed that 4,379 transposable elements (TEs; 58% of all classifiable rice TEs) were expressed collectively in the vegetative and reproductive shoot apex. Furthermore, in the reproductive shoot apex, 214 TEs were silenced by florigen. Our results suggest a link between floral induction and regulation of TEs.

在水稻茎端花诱导过程中,类FT蛋白诱导转座子沉默

高等植物中,花诱导是一个至关重要的发育步骤。最近研究表明,FT及其同源基因编码的蛋白,成花素,是一个可移动的花器官激活因子,在叶片中合成后转移到茎顶端,水稻中的成花素是Hd3a蛋白。14-3-3蛋白能够介导Hd3a与转录因子OsFD1互作,在水稻APETALA1同源基因OsMADS15的启动子上,形成三重结构的成花素激活复合物。但是一些关键信息,包括类FT蛋白、成花素激活复合物组件和下游基因的时空重叠性仍不清楚。我们研究证实,在水稻茎端的相同区域,Hd3a能够与其它成花素激活复合物成员以及转录靶基因共存。但是,利用野生型和成花素失活的RNAi植株的茎端组织进行RNA测序分析,表明有4379个转座因子(TEs,占水稻TEs中的58%)集中在营养生长和生殖生长的茎顶端表达。同时在生殖生长的茎顶端,214个TEs被成花素沉默。我们结果表明花诱导与TEs的调控存在一定联系。


基因列表
  成花素基因;抽穗期基因;生育期基因;光周期敏感基因;感光基因 Hd3a; FT
  MADS盒基因 OsMADS15; DEP