Evaluation of Nucleotide Diversity of Waxy B Gene in some of Wild and Cultivated Wheat

Improving the quality of bread wheat is an important issue. It has attracted the attention of many researchers over the years, and in recent decades, various methods have been developed to evaluate this goal. One of the most important goals in wheat breeding programs is to improve the quality of wheat bakery. Waxy proteins that responsible for the expression of GBSS enzyme in wheat that control the ratio of amylose to amylopectin in starch, These proteins in hexaploid wheat are controlled by three genes, Wx-D1, Wx-B1, Wx-A1 and those have a key role in quality of wheat flour. The goal of this study was to investigate the nucleotide diversity of Wx-B1 gene in wild and crop cultivars and also to investigate the phylogenetic relationships between wheat and their ancestors based on waxy genes.

In the present study, the phylogenetic relationships of the waxy B gene in 34 samples including 4 species of Aegilops genus and 28 cultivars of wheat and 2 species of wild wheat were evaluated using PCR and sequencing techniques  in Ilam university.

Sequences alignment results of Wx-B-seq1 and Wx-B-seq2 genes showed there are very high conserved regions between crop and wild wheat, although in some regions there is single nucleotide diversity between crop and wild wheat. The results of similarity matrix of Wx-B-seq1 showed the highest distance was related to Sardari cultivar and the lowest distance was related to Aegilops.umbellulata sample. The similarity matrix of the Wx-B-seq2 gene showed this gene did not change much in crop cultivars except Shahi cultivar, while the two wild wheat samples T.boeticum and T.dicoccooides showed a very large genetic distance compared to the crop cultivars. The results of the substitution matrix estimation based on the maximum likelihood method for Wx-B-seq1 and Wx-B-seq2 genes showed the highest and lowest contributions of nucleotide substitution are purine and pyrimidine, respectively. Also, UPGMA clustering results for Wx-B-seq1 and Wx-B-seq2 genes divided the samples into two and three main groups, respectively.

The overall results show that the diversity observed in wild samples and The ancestors of crop wheat can be a good candidate for further studies to determine whether these changes will lead to protein content or not.