Cloning and Diversity Analysis of TaHKT2;2 in Hexaploid Wheat.

In order to study the roles of members of HKT gene family in wheat, TaHKTl; 2 was isolated by using homologous cloning strategy and screening genomic BAC library. TaHKTl-, 2 genes were mapped on chromosomes 7A, 7B and 7D, named as TaHKTl-, 2-7A, TaHKTl; 2-7B, and TaHKTl-, 1-1D, respectively. TaHKTl; 2 and TaHKTl; 1 had the same genetic structure, composed of three exons and two introns, and formed a cluster with TaHKTl; 1 on the phylogenetic tree of plant HKT transporters. The coding sequences of TaHKTl-, 1-1A, TaHKTl; 1-7B, and TaHKTl; 1-1D were 1 602, 1 602 and 1 596 bp long, respectively, but TaHKTl; 1-7D cDNA sequence was not isolated by RT-PCR in eight wheat varieties. The natural diversity of TaHKTl; 2 genes was analyzed by cloning and sequencing from 12 wheat varieties. The results showed that TaHKTl;2-7A was found to be more diverse than TaHKTl; 1-1B and TaHKTl; 1-1D. Only a few bases changed in the alleles of TaHKTl; 2 genes in wheat. No amino-acid natural variation lay in the P-loops of deduced protein sequences of all alleles of TaHKTl; 2 in 12 wheat varieties. The identity of coding sequences was much higher than that of 5' flanking regions of TaHKTl; 2 genes. TaHKTl; 2 might be selected over the course of wheat domestication and belonged to domestication gene. [ABSTRACT FROM AUTHOR]