Sixty Million Years in Evolution of Soft Grain Trait in Grasses: Emergence of the Softness Locus in the Common Ancestor of Pooideae and Ehrhartoideae, after their Divergence from Panicoideae
Sixty Million Years in Evolution of Soft Grain Trait in Grasses: Emergence of the Softness Locus in the Common Ancestor of Pooideae and Ehrhartoideae, after their Divergence from Panicoideae
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DOI：
10.1093/molbev/msp076
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发表时间：
2009-07-01
影响因子：
10.7
通讯作者：
Chalhoub, Boulos
中科院分区：
文献类型：
--
作者：
Charles, Mathieu;Tang, Haibao;Chalhoub, Boulos
玉米、高粱、水稻和麦草(禾本科)是世界上最重要的粮食作物，表现出不同的“谷粒胚乳结构”。这一特性在小麦中得到了广泛的研究，因为它在决定小麦籽粒产品质量方面起着关键作用。小麦硬度(Ha)基因座的GSP-1、PINA和PinB基因编码的籽粒软化蛋白-1和Puroindoline A和B(籽粒贮藏蛋白)是小麦籽粒软硬性状的主要决定因素。通过比较小麦、蕨类、水稻和高粱的Ha同源区域的基因组序列，探讨了禾本科植物籽粒胚乳质地的起源和进化。结果表明，Ha-like基因在小麦和短柄蕨中存在，而在高粱中不存在。水稻中存在一种类似Ha的基因的截断残留物。对这些草种基因组的共性分析表明，在通过全基因组复制产生的70My的平行Ha区中，只有一个含有Ha类基因。与禾本科牧草储粮蛋白基因的比较基因组分析和进化比较表明，在禾本科(Triticeae和Brachypodieae部落)和Ehrhartoideae(水稻)的共同祖先中出现了一个祖先类Ha基因，作为醇溶蛋白基因家族的新成员，它们与Panicoideae(高粱)的分歧在60-50my之间。随后，它在埃哈托亚科消失了。反复出现的重复、缺失和/或截断独立发生，似乎是草类基因进化的特征。类Ha基因在小麦等小麦中获得了新的功能，为软粒表型奠定了基础。在一些小麦品种中，这些基因的丢失反过来导致硬胚乳种子。
Together maize, Sorghum, rice, and wheat grass (Poaceae) species are the most important cereal crops in the world and exhibit different "grain endosperm texture." This trait has been studied extensively in wheat because of its pivotal role in determining quality of products obtained from wheat grain. Grain softness protein-1 and Puroindolines A and B (grain storage proteins), encoded by Ha-like genes: Gsp-1, Pina, and Pinb, of the Hardness (Ha) locus, are the main determinants of the grain softness/hardness trait in wheat. The origin and evolution of grain endosperm texture in grasses was addressed by comparing genomic sequences of the Ha orthologous region of wheat, Brachypodium, rice, and Sorghum. Results show that the Ha-like genes are present in wheat and Brachypodium but are absent from Sorghum bicolor. A truncated remnant of an Ha-like gene is present in rice. Synteny analysis of the genomes of these grass species shows that only one of the paralogous Ha regions, created 70 My by whole-genome duplication, contained Ha-like genes. The comparative genome analysis and evolutionary comparison with genes encoding grain reserve proteins of grasses suggest that an ancestral Ha-like gene emerged, as a new member of the prolamin gene family, in a common ancestor of the Pooideae (Triticeae and Brachypoidieae tribes) and Ehrhartoideae (rice), between 60 and 50 My, after their divergence from Panicoideae (Sorghum). It was subsequently lost in Ehrhartoideae. Recurring duplications, deletions, and/or truncations occurred independently and appear to characterize Ha-like gene evolution in the grass species. The Ha-like genes gained a new function in Triticeae, such as wheat, underlying the soft grain phenotype. Loss of these genes in some wheat species leads, in turn, to hard endosperm seeds.