小麦CO-like基因TaCO9的克隆及分析

CO蛋白(CONSTANS)是光周期途径中重要的调控因子,为了从普通小麦中进一步挖掘COlike基因,利用同源克隆的方法得到与大麦HvCO9基因同源的小麦TaCO9基因。结果表明,在冬性品种西农889中,初步克隆得到TaCO9基因的三个同源序列,分别命名为TaCO9-1、TaCO9-2、TaCO9-3。其cDNA序列全长均为870bp,开放阅读框为1 977bp,编码289个氨基酸,含有CO-like蛋白家族典型的CCT结构域,但不含B-box结构域;而在春性品种中发现TaCO9-1序列的第二外显子区域有6个碱基的插入,利用中国春缺-四体材料将该序列定位于小麦的1A染色体,命名为TaCO9-1A。系统发育分析表明,TaCO9蛋白与水稻Ghd7及大麦HvCO9位于同一分支。空间结构分析表明,其CCT结构域的NF-YA2区域较为保守,而该区域与CCAAT box互作相关。本研究克隆得到的TaCO9基因可能是小麦CO-like基因家族的新成员,与大麦HvCO9基因的结构相似,可作为新的小麦光周期候选基因加以研究利用。

Cloning and Analysis of CO-like Gene TaCO9 from Wheat (Triticum aestivum L.)

To isolate CO-like gene in wheat, the homologous cloning method was used to isolate the related gene based on the sequence of HvCO9 in barely. Here a novel gene TaCO9 that encoding a CO-like protein was cloned from hexaploid wheat (Triticum aestivum L.). There were three homologous genes of TaCO9 in winter wheat cultivar Xinong889 and the cDNAs of the three genes were 870bp in length, encoding 289 amino acids composed of CCT domain, but not the B-box domain. A 6 bp insertion in the second exon was detected in a spring wheat variety, Ningchun 4, and a marker based on the divergence in the downstream sequence of intron specialized in the inserted sequence was developed. Using this maker and Chinese Spring nulli-tetrasomic lines, the mutant TaCO9 gene in Ningchun4 was located on wheat chromosome 1A, named as TaCO9-1A. A phylogenetic analysis showed that the TaCO9 protein was classified into the same branch of the CO-like tree such as Ghd7 protein in rice and HvCO9 protein in barely, which were all negative regulators of flowering. As a novel member of CO-like family in wheat, TaCO9 is similar to HvCO9 and expected to be a candidate gene for photoperiod research in wheat.