Zhang Lujun, Li Zhixin, Fan Renchun, Wei Bo, Zhang Xiangqi
State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Int J Mol Sci. 2016 Jul 19;17(7):1115. doi: 10.3390/ijms17071115.
The Roegneria of Triticeae is a large genus including about 130 allopolyploid species. Little is known about its high-molecular-weight glutenin subunits (HMW-GSs). Here, we reported six novel HMW-GS genes from R. nakaii and R. alashanica. Sequencing indicated that Rny1, Rny3, and Ray1 possessed intact open reading frames (ORFs), whereas Rny2, Rny4, and Ray2 harbored in-frame stop codons. All of the six genes possessed a similar primary structure to known HMW-GS, while showing some unique characteristics. Their coding regions were significantly shorter than Glu-1 genes in wheat. The amino acid sequences revealed that all of the six genes were intermediate towards the y-type. The phylogenetic analysis showed that the HMW-GSs from species with St, StY, or StH genome(s) clustered in an independent clade, varying from the typical x- and y-type clusters. Thus, the Glu-1 locus in R. nakaii and R. alashanica is a very primitive glutenin locus across evolution. The six genes were phylogenetically split into two groups clustered to different clades, respectively, each of the two clades included the HMW-GSs from species with St (diploid and tetraploid species), StY, and StH genomes. Hence, it is concluded that the six Roegneria HMW-GS genes are from two St genomes undergoing slight differentiation.
小麦族鹅观草属是一个大属，包含约130个异源多倍体物种。关于其高分子量谷蛋白亚基（HMW-GSs）的了解甚少。在此，我们报道了来自 Nakaii 鹅观草和阿拉善鹅观草的6个新型HMW-GS基因。测序表明，Rny1、Rny3和Ray1具有完整的开放阅读框（ORFs），而Rny2、Rny4和Ray2含有框内终止密码子。这6个基因均具有与已知HMW-GS相似的一级结构，但也表现出一些独特特征。它们的编码区明显短于小麦中的Glu-1基因。氨基酸序列显示，这6个基因均为y型中间型。系统发育分析表明，来自具有St、StY或StH基因组的物种的HMW-GSs聚集在一个独立的分支中，与典型的x型和y型簇不同。因此，Nakaii鹅观草和阿拉善鹅观草中的Glu-1位点是进化过程中一个非常原始的谷蛋白位点。这6个基因在系统发育上分为两组，分别聚集到不同的分支中，两个分支中的每一个都包括来自具有St（二倍体和四倍体物种）、StY和StH基因组的物种的HMW-GSs。因此，可以得出结论，这6个鹅观草HMW-GS基因来自两个正在经历轻微分化的St基因组。
