水稻长日抑制基因PhyB的多样性及区域适应性初探

Phy 是在长日照条件下抑制水稻开花的关键基因,但目前对水稻PhyB基因的遗传基础还不清楚,研究其分子遗传机制,对于培育光周期适应性广的品种以及扩大水稻种植区域具有重要意义。本研究选择78份亚洲栽培稻(34份籼稻和44份粳稻)及47份野生稻进行测序,对Phy B基因的核苷酸多态性、单倍型进行分析,计算籼稻、粳稻和野生稻的遗传多样性。结果表明,Phy B基因共有28个单倍型,其中有2个高频率的单倍型分别存在于2个栽培稻亚种中。从Network图可以看出栽培稻分为2组(A组和B组),A组栽培稻包括全部的籼稻和4个粳稻个体,B组栽培稻全是粳稻品种。亲缘地理学分析发现,A、B两组栽培稻具有明显不同的地理分布格局,且A组和B组开花时间差异显著,说明Phy B基因的2个高频率单倍型在2个栽培稻亚种中具有区域适应性,Phy B基因在栽培稻中具有明显的驯化信号,随着水稻种植区域的扩大,进化出适应不同地域特有的等位基因,导致开花时间对不同地区的区域适应性及多样性。

Genetic diversity and regional adaptability of long day suppression genes for PhyB in rice

Detailed knowledge of the molecular mechanisms of controlling flowering time will facilitate understanding the adaptation mechanism in cultivated rice and enable breeders to design appropriate genotypes for distinct preferences. Previous studies showed that PhyB suppress flowering in long day (LD) conditions, however, how the genetic variation of PhyB is associated with flowering time in different varieties in rice remains unknown. In this study, we sequenced 78 cultivated rice varieties (34 indica varieties and 44 japonica varieties) and 47 wild relatives of rice for PhyB. We obtained the following results: 28 haplotypes were detected among the 125 accessions, and there were two prevalent haplotypes which mainly existed in cultivated rice. The Network indicated that the cultivated rice could be divided into two groups (group A and group B), in which, group A included all indica individuals and 4 japonica individuals, and group B included the rest of japonica individuals. Further geographical analysis showed that group A and group B had distinct geographic distribution pattern, and the flowering time between group A and group B were significantly different. In addition, the genetic diversity result showed that wild rice population harbored higher genetic diversity than did the two cultivated subspecies (indica and japonica). Thus, we inferred that the two prevalent haplotypes existed in two cultivated subspecies are associated with regional adaptability. PhyB had obvious domestication signals in cultivated rice. It evolved specific alleles to adapt the day time suitable for flowering of rice varieties in different regions.