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Mechanisms, origin and heredity of Glu-1Ay silencing in wheat evolution and domestication

Luo, Guangbin, Song, Shuyi, Zhao, Liru, Shen, Lisha, Song, Yanhong, Wang, Xin, Yu, Kang, Liu, Zhiyong, Li, Yiwen, Yang, Wenlong, Li, Xin, Zhan, Kehui, Zhang, Aimin, Liu, Dongcheng
Theoretical and applied genetics 2018 v.131 no.7 pp. 1561-1575
Triticum aestivum, Triticum monococcum subsp. aegilopoides, Triticum monococcum subsp. monococcum, Triticum urartu, alleles, diploidy, domestication, evolution, glutenins, hexaploidy, inheritance (genetics), progeny, retrotransposons, stop codon, tetraploidy, wheat
KEY MESSAGE: Allotetraploidization drives Glu-1Ay silencing in polyploid wheat. The high-molecular-weight glutenin subunit gene, Glu-1Ay, is always silenced in common wheat via elusive mechanisms. To investigate its silencing and heredity during wheat polyploidization and domestication, the Glu-1Ay gene was characterized in 1246 accessions containing diploid and polyploid wheat worldwide. Eight expressed Glu-1Ay alleles (in 71.81% accessions) and five silenced alleles with a premature termination codon (PTC) were identified in Triticum urartu; 4 expressed alleles (in 41.21% accessions), 13 alleles with PTCs and 1 allele with a WIS 2-1A retrotransposon were present in wild tetraploid wheat; and only silenced alleles with PTC or WIS 2-1A were in cultivated tetra- and hexaploid wheat. Both the PTC number and position in T. urartu Glu-1Ay alleles (one in the N-terminal region) differed from its progeny wild tetraploid wheat (1–5 PTCs mainly in the repetitive domain). The WIS 2-1A insertion occurred ~ 0.13 million years ago in wild tetraploid wheat, much later than the allotetraploidization event. The Glu-1Ay alleles with PTCs or WIS 2-1A that arose in wild tetraploid wheat were fully succeeded to cultivated tetraploid and hexaploid wheat. In addition, the Glu-1Ay gene in wild einkorn inherited to cultivated einkorn. Our data demonstrated that the silencing of Glu-1Ay in tetraploid and hexaploid wheat was attributed to the new PTCs and WIS 2-1A insertion in wild tetraploid wheat, and most silenced alleles were delivered to the cultivated tetraploid and hexaploid wheat, providing a clear evolutionary history of the Glu-1Ay gene in the wheat polyploidization and domestication processes.