Identification of Oryza sativa’s Awn Development Regulatory Gene Orthologs in Triticinae Accessions

Abstract

Information on the genetic control of awn development in bread wheat is currently limited to the identification of three genes that suppress awnedness, Hd, B1, and B2, and no promoters have yet been identified. Another Gramineae species, Oryza sativa, has more than ten genes involved in awn morphogenesis. This article presents results of the wheat genome sequence analysis for the search of genes orthologous to the known awn development regulators in rice, TOB1, ETT2, and DL. Using bioinformatic methods, three genes, TaTOB1, TaETT2, and TaDL, are identified in the bread wheat genome; their location is defined on the chromosomes of the second, third, and fourth homoeologous groups, respectively. The polymorphisms between homoeoalleles of the genes located on subgenomes A, B, and D are described. Identified polymorphisms include variation in the length of exons and introns in all the three genes, variation in the number of exons and introns for the TaETT2 gene homoeoalleles, inversion of TaDL-B homoeoallele relative to the TaDL-A and TaDL-D, and inversion of TaETT2-B and TaETT2-D relative to TaETT2-A. With the PCR method using primers designed for the TaTOB1 gene sequence, the homoeoalleles of this gene were identified in the genomes Au, Ab, B, G, D, SSh, M, U, and T in diploid, tetraploid, and hexaploid wheat species. The marker potential of two pairs of primers for the TaTOB1 gene for the study into the genome structure of the introgressive wheat lines in relation to this gene is shown.