Allelic Diversity of Hordein-Coding Loci Hrd A and Hrd B in Cultivated (Hordeum vulgare L.) and Wild (Hordeum spontaneum C. Koch) Barley from Jordan (as a Part of the Fertile Crescent)

Abstract

Starch gel electrophoresis was used to study polymorphism of hordeins encoded by the Hrd A and Hrd B loci in 34 local varieties of cultivated barley and 19 accessions of wild barley from Jordan. Thirty-two and 26 alleles for the Hrd A locus were identified in H. vulgare and H. spontaneum, respectively, and 42 and 32 alleles were detected for the Hrd B locus. Allelic frequencies of the Hrd A and Hrd B loci in cultivated barley varied within the range of 0.0029–0.2707 and 0.0029–0.1824, respectively, and within the range of 0.0105–0.1263 and 0.0105–0.0947 in wild barley. Six out of 52 alleles of Hrd A and four out of 70 alleles of Hrd В were common between Jordanian H. spontaneum and H. vulgare. Two of six common alleles of the Hrd A locus found in Jordanian wild and cultivated barley and one common allele of the Hrd В locus were discovered earlier among H. spontaneum accessions from Iran, Turkey, and Syria. However, three common alleles of Hrd A and three common alleles of Hrd В were detected only in Jordanian accessions of wild and cultivated barley. According to archaeological records, the earliest indications of barley utilization in Jordan appeared only in 6700 BC, whereas they were dated in Syria to 9000 BC and in Israel to 17 000 BC. We concluded that Jordan cannot be considered as domestication center of barley. At the same time, Jordanian H. spontaneum could have contributed some alleles of hordein-coding loci to the gene pool of H. vulgare owing to introgression resulting from spontaneous hybridization over the course of crop diffusion from the domestication center outward.