拟斯卑尔脱山羊草属物种中高分子量麦谷蛋白亚基的新变异体与进化及小麦育种的关系
Novel variants of HMW glutenin subunits from Aegilops section Sitopsis species in relation to evolution and wheat breeding.
作者信息
Jiang Qian-Tao, Ma Jian, Wei Yu-Ming, Liu Ya-Xi, Lan Xiu-Jin, Dai Shou-Fen, Lu Zhen-Xiang, Zhao Shan, Zhao Quan-Zhi, Zheng You-Liang
机构信息
Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
出版信息
BMC Plant Biol. 2012 May 30;12:73. doi: 10.1186/1471-2229-12-73.
BACKGROUND
High molecular weight glutenin subunits (HMW-GSs), encoded by the genes at Glu-1 loci in wheat and its related species, are significant in the determination of grain processing quality. However, the diversity and variations of HMW-GSs are relatively low in bread wheat. More interests are now focused on wheat wild relatives in Triticeae. The genus Aegilops represents an important germplasm for novel HWM-GSs and other useful genes for wheat genetic improvement.
RESULTS
Six novel Glu-1 alleles and HMW-GSs were identified and characterized from three species of Aegilops section Sitopsis (S genome). Both open reading frames (ORFs) and promoter regions of these Glu-1 alleles were sequenced and characterized. The ORFs of Sitopsis Glu-1 genes are approximately 2.9 kb and 2.3 kb for x-type and y-type subunits, respectively. Although the primary structures of Sitopsis HMW-GSs are similar to those of previously reported ones, all six x-type or y-type subunits have the large fragment insertions. Our comparative analyses of the deduced amino acid sequences verified that Aegilops section Sitopsis species encode novel HMW-GSs with their molecular weights larger than almost all other known HMW-GSs. The Glu-1 promoter sequences share the high homology among S genome. Our phylogenetic analyses by both network and NJ tree indicated that there is a close phylogenetic evolutionary relationship of x-type and y-type subunit between S and D genome.
CONCLUSIONS
The large molecular weight of HMW-GSs from S genome is a unique feature identified in this study. Such large subunits are resulted from the duplications of repetitive domains in Sitopsis HMW-GSs. The unequal crossover events are the most likely mechanism of variations in glutenin subunits. The S genome-encoded subunits, 1Dx2.2 and 1Dx2.2* have independent origins, although they share similar evolutionary mechanism. As HMW-GSs play a key role in wheat baking quality, these large Sitopsis glutenin subunits can be used as special genetic resources for wheat quality improvement.
背景
由小麦及其近缘物种中Glu-1位点的基因编码的高分子量谷蛋白亚基（HMW-GSs），在决定谷物加工品质方面具有重要意义。然而，面包小麦中HMW-GSs的多样性和变异性相对较低。目前更多的研究兴趣集中在小麦族的野生近缘种上。山羊草属是小麦遗传改良中新型HWM-GSs和其他有用基因的重要种质资源。
结果
从山羊草属拟斯卑尔脱组（S基因组）的三个物种中鉴定并表征了六个新的Glu-1等位基因和HMW-GSs。对这些Glu-1等位基因的开放阅读框（ORFs）和启动子区域进行了测序和表征。拟斯卑尔脱组Glu-1基因的ORFs，x型和y型亚基分别约为2.9 kb和2.3 kb。尽管拟斯卑尔脱组HMW-GSs的一级结构与先前报道的相似，但所有六个x型或y型亚基都有大片段插入。我们对推导氨基酸序列的比较分析证实，山羊草属拟斯卑尔脱组物种编码新型HMW-GSs，其分子量大于几乎所有其他已知的HMW-GSs。Glu-1启动子序列在S基因组中具有高度同源性。我们通过网络和NJ树进行的系统发育分析表明，S基因组和D基因组的x型和y型亚基之间存在密切的系统发育进化关系。
结论
本研究鉴定出S基因组HMW-GSs的大分子量是一个独特特征。这种大亚基是由拟斯卑尔脱组HMW-GSs中重复结构域的重复产生的。不等交换事件是谷蛋白亚基变异最可能的机制。S基因组编码的亚基1Dx2.2和1Dx2.2* 虽然具有相似的进化机制，但有独立的起源。由于HMW-GSs在小麦烘焙品质中起关键作用，这些大的拟斯卑尔脱组谷蛋白亚基可作为小麦品质改良的特殊遗传资源。
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