Allelic variation and geographical patterns of prolamins in the USDA-ARS Khorasan wheat germplasm collection

Abstract

Khorasan wheat, Triticum turgidum ssp. turanicum (Jakubz), is an ancient cultivated wheat possessing several characteristics that may be useful for durum wheat improvement. In this paper, the allelic variation of prolamins, principal determinants of pasta quality, has been studied in 77 accessions from the USDA-ARS germplasm collection. Some prolamin subunits difficult to identify by standard electrophoretic methods were analyzed by molecular and proteomic techniques. These analyses allowed identifying unambiguously the subunits combination HMW-GS 7+16 (usually mistaken for 13+16) and the 13+8 (HMW-GS) not found so far in wheat. In total, 22 different genotypes were found for the entries from 21 countries analyzed. Prolamin alleles related to good quality in durum wheat have been identified. Also, new allelic variants were identified at almost all the loci, providing a new source of genetic variability with a potential use in breeding. Two geographical distribution patterns of prolamin alleles, with contrasting differences in pasta quality, were detected: one for the Southwest of Asia, and other for the Mediterranean zone. Seven accessions, mainly from Ethiopia and not included in any of those two groups, were rather unique. The results obtained in this study can help to select breeding material and in a more efficient use of the collection. © Crop Science Society of America.