Variations in Hd1 proteins, Hd3a promoters, and Ehd1 expression levels contribute to diversity of flowering time in cultivated rice

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Yasuyuki Takahashi, Kosuke M. Teshima, Shuji Yokoi, Hideki Innan, Ko Shimamoto
Proceedings of the National Academy of Sciences, 2009, 106(11): 4555-4560  DOI: 10.1073/pnas.0812092106;      追溯原文......本站官方QQ群:62473826
cereal; florigen; natural variation; photoperiod; polymorphism

Rice is a facultative short-day plant, and molecular genetic studies have identified the major genes involved in short-day flowering. However, the molecular mechanisms promoting the diversity of flowering time in cultivated rice are not known. We used a core collection of 64 rice cultivars that represent the genetic diversity of 332 accessions from around the world and studied the expression levels and polymorphisms of 6 genes in the short-day flowering pathway. The RNA levels of Heading date 3a (Hd3a), encoding a floral activator, are highly correlated with flowering time, and there is a high degree of polymorphism in the Heading date 1 (Hd1) protein, which is a major regulator of Hd3a expression. Functional and nonfunctional alleles of Hd1 are associated with early and late flowering, respectively, suggesting that Hd1 is a major determinant of variation in flowering time of cultivated rice. We also found that the type of Hd3a promoter and the level of Ehd1 expression contribute to the diversity in flowering time and Hd3a expression level. We evaluated the contributions of these 3 factors by a statistical analysis using a simple linear model, and the results supported our experimental observations.

Hd1蛋白、Hd3a基因启动子和Ehd1表达水平的差异引起栽培稻中抽穗期的多样性

水稻是一个不严格的短日照植物,分子遗传学研究已经鉴定出了控制短日照下抽穗的主要基因。但是控制栽培稻抽穗期多样性的分子机制并不清楚。我们从世界范围内收集了64份水稻核心种质代表了332个水稻遗传多态品种,检测了短日照下水稻抽穗通路中6个基因的表达和多态性。编码开花激活因子的Hd3a的RNA水平与抽穗期高度相关,同时调节Hd3a表达的主要因子Hd1的也具有高度多态性。有功能的Hd1等位基因和没有功能的等位基因分别对应早抽穗和晚抽穗,表明Hd1是决定这些水稻品种抽穗期多样性的主要因子。我们还发现Hd3a启动子的类型和Ehd1的表达水平也与抽穗期的多样性和Hd3a的表达水平有关。通过简单线性模型的统计分析方法,我们评估了这3个因子在决定抽穗期多样性中的贡献程度,得到的结果支持了我们的实验结果。
结果:Hd3a的表达水平与栽培稻的抽穗期高度相关;Hd3a启动子区和编码编码区中的核酸多态性;Ehd1和OsMADS51的核酸多态性; Hd1的核酸多态性;Hd1等位基因的多样性与抽穗期的关系;控制水稻抽穗期多样性的其他因子;抽穗期的线性模型分析和栽培稻中Hd3a的表达水平。


基因列表
  抽穗期基因 Hd1
  早穗基因 Ehd1
  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