Divergent functions of the GAGA-binding transcription factor family in rice 

First author: Rong Gong; Affiliations: Huazhong Agricultural University (华中农业大学): Wuhan, China

Corresponding author: Sibin Yu (余四斌)

OsGBPs are a small family of four genes in rice (Oryza sativa L.) that function as transcription factors recognizing the GAGA motif; however, their functions in plant growth and development remain unclear. Here we report the functions of OsGBPs in plant growth and grain development. Knock-down and knock-out of OsGBP1 promoted seedling growth and enhanced grain length, whereas overexpression of OsGBP1 exhibited the opposite effect on seedling growth and grain length, indicating that OsGBP1 repressed grain length and seedling growth. In addition, overexpression of OsGBP1 led to delayed flowering time and suppressed plant height. OsGBP1 could regulate OsLFL1 expression through binding to the (GA)12 element of its promoter. In contrast, OsGBP3 induced grain length and plant height. Grain length and plant height were decreased in OsGBP3RNAi lines and were increased in OsGBP3 overexpression lines. We also found a synergistic effect (协同效应) of these two genes on grain width and plant growth. RNAi of both OsGBP1 and OsGBP3 resulted in severe dwarfism (侏儒), compared with RNAi of a single gene. These results suggest the presence of functional divergence of OsGBPs in the regulation of grain size and plant growth; these results enrich our understanding of the roles of GAGA-binding transcription factors in the regulatory pathways of plant development.

OsGBPs是一类水稻中较小的基因家族，仅含4个成员，其主要作为识别GAGA基序的转录因子实现功能。然而，这些基因在植物生长和发育中的作用还不清楚。本文报道了OsGBPs基因在植物生长和籽粒发育中的作用。敲低或敲除OsGBP1基因均会促进水稻的生长，增长籽粒的长度，而过表达OsGBP1基因则会得到相反的表型，表明OsGBP1基因会抑制植株的生长及籽粒的发育。另外，过表达OsGBP1基因还会导致植株的晚花表型，并且抑制植株的高生长。OsGBP1基因可以通过结合到OsLFL1基因启动子区的(GA)12元件从而调控OsLFL1基因的表达。相反，OsGBP3基因会诱导籽粒的长度和植株的高度。OsGBP3RNA干扰的植株中，籽粒长度和植株高度有所降低，而在OsGBP3过表达的植株中则有所提升。作者还发现了这两个OsGBPs基因在籽粒宽度和植株生长上存在协同效应。同时对OsGBP1和OsGBP3基因进行RNA干扰会导致严重的植物矮小，比只干扰其中一个基因表型来得更加强烈。本文的研究结果显示OsGBPs基因在调控籽粒大小和植株生长上存在功能的分化，进一步加深了我们对于GAGA结合转录因子在植物发育的调控通路上所扮演的重要作用。

通讯：余四斌 (http://cpst.hzau.edu.cn/info/1012/3344.htm)

研究方向：水稻新种质创建、基因发掘与分子育种。

doi: 10.1111/tpj.13837

Journal: the plant journal

First Published date: 05 March, 2018

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