A new α-gliadin gene family for wheat breeding: somatic introgression line II-12 derived from Triticum aestivum and Agropyron elongatum

Abstract

Ninety-five α-gliadin open reading frames were cloned and sequenced from the somatic hybrid wheat introgression line II-12 and its parents Triticum aestivum cv. Jinan177 (JN177) and Agropyron elongatum. Novel α-gliadin genes were found to originate via point mutation, unequal crossover or slippage of a parental gene, demonstrating that new genes could be rapidly created through somatic hybridization in a manner similar to that previously shown for high-molecular-weight glutenin subunits (HMW-GS) genes. The data reveal the composition and origin of the α-gliadin gene in II-12, showing that: (1) most were homologous to those of JN177; (2) a few were derived direct from A. elongatum; and (3) some new genes were created de novo. A particular quality attribute of interest was the presence or absence of celiac disease (CD) epitopes, which were found to be four times more common among α-gliadin genes from the parent wheat JN177 than in those from A. elongatum. Although four types of CD epitopes were found in introgression line II-12, the number of genes encoded CD epitopes was lower than in JN177 due to the occurrence of pseudogenes. We discuss the benefit of these α-gliadins to wheat breeding.