GhPHYB基因的基因组鉴定及进化分析

Genome-Wide Identification and Evolution Analysis of Upland Cotton PHYB Gene

摘要:

在陆地棉异源四倍体标准系TM-1基因组数据库中共鉴定获得2个PHYB基因，这2个基因分别分布在A10和D10亚基因组。利用生物信息学方法对这两个基因进行初步分析表明，棉花的PHYB具有其他植物PHYB相同的基序和结构域，不管是数目还是分部位置都比较一致；不同植物的PHYB氨基酸序列同源性比对及构建的进化树都显示棉花的PHYB同可可的在同源性和进化关系上都是最近，同水稻、玉米等单子叶植物的同源性及进化关系较低；基因结构的比对结果同样显示植物PHYB基因在进化上比较保守；棉花PHYB存在几十个可能磷酸化的位点，这些位点的磷酸化作用可能影响光敏色素的功能及其介导的信号通路；PHYB直系同源基因和旁系同源基因的K_a/K_s比值均小于1，说明这些基因在进化过程中受到纯化选择作用。本研究结果可为陆地棉PHYB基因的深入研究提供理论基础。

Abstract:

Two PHYB genes were identified from the genome sequence database of allotetraploid cotton（Gossypium hirsutum L. acc. TM-1）, which were found to be distributed on subgenome A10 and D10. The preliminary bioinformatic analysis indicated that the PHYB genes of upland cotton had the same motifs and domains with the PHYB genes in other plant species, and even the number and location of the motifs and domains of these PHYB genes were consistent. The PHYB amino acid sequence alignment and the phylogenetic tree constructed based on PHYB amino acid sequence of these plant species indicated that the two PHYB genes in upland cotton had higher homology and closer evolutionary relationships with cocoa（Theobroma cacao）, but lower similarity to PHYB genes in monocotyledonous plants, such as rice（Oryza saitva） and corn（Zea mays）. The comparison results of PHYB gene structure also showed that the plant PHYB gene was more conservative in evolution. The autophosphorylation of dozens of autophosphorylation sites in PHYB maybe essential for their function and plays a significant role in regulating phytochrome-mediated signal transduction pathways. The K_a/K_s values of orthologous and paralogous genes of PHYB were all less than 1, indicated that those genes mainly experienced purifying selection among evolution. The results of this paper would provide a theoretical basis on intensive study of Gossypium hirsutum PHYB genes.