Detection of single nucleotide polymorphisms in 24 kDa dimeric α-amylase inhibitors from cultivated wheat and its diploid putative progenitors

Seventeen new genes encoding 24 kDa family dimeric α-amylase inhibitors had been characterized from cultivated wheat and its diploid putative progenitors. And the different α-amylase inhibitors in this family, which were determined by coding regions single nucleotide polymorphisms (cSNPs) of their genes, were investigated. The amino acid sequences of 24 kDa α-amylase inhibitors shared very high coherence (91.2%). It indicated that the dimeric α-amylase inhibitors in the 24 kDa family were derived from common ancestral genes by phylogenetic analysis. Eight α-amylase inhibitor genes were characterized from one hexaploid wheat variety, and clustered into four subgroups, indicating that the 24 kDa dimeric α-amylase inhibitors in cultivated wheat were encoded by multi-gene. Forty-five cSNPs, including 35 transitions and 10 transversions, were found, and resulted in a total of ten amino acid changes. The cSNPs at the first site of a codon cause much more nonsynonymous (92.9%) than synonymous mutations, while nonsynonymous and synonymous mutations were almost equal when the cSNPs were at the third site. It was observed that there was Ile105 instead of Val105 at the active region Val104-Val105-Asp106-Ala107 of the α-amylase inhibitor by cSNPs in some inhibitors from Aegilops speltoides, diploid and hexaploid wheats.