RESUMO
Wheat is a widely cultivated crop and it is one of the major food sources worldwide. Among the various tools used to study diversity of wheat species, the internal transcribed spacer (ITS) assessment emerges to be the more appropriate approach. In the present study, we evaluated 15 genotypes of Iranian wheat cultivars (wild, native, and breed) using ITS gene sequences. Similarity matrices and dendrogram of phylogenic relationship were constructed using Mega ver6 software. We report the major nucleotide changes in the same position between diploid and hexaploid species. dN/dS ratio for diploid, tetraploid, and hexaploid species indicated a pure selection in the examined gene, with no key changes in the genes, and 91% ITS diversity within individual wheat was evident. The results suggest that as evolution moves forward, nucleotide changes are reduced so that only a few changes in nucleotides occur. ITS marker can distinguish different wheat genotypes at the genomic level and thus prove to be the most appropriate assessment tool for analyzing inter and intra-species relationships.