Water-soluble proteins of mature barley endosperm: genetic control, polymorphism, and linkage with β-amylase and spring/winter habit.

Water-soluble proteins (WSP-2 and WSP-3) and β-amylase (β-AMY-1) were extracted from mature endosperms of 44 spring and 39 winter barley genotypes. The protein and enzyme isoforms were separated in isoelectric focusing gels with a pH gradient of 4-6.5. The Wsp-3 and β-Amy-1 loci were located to chromosomes 4H using the wheat/barley chromosome addition lines. Segregation analysis of F2 and doubled haploid populations showed Wsp-2 and β-Amy-1 to be tightly linked, with a map distance of 11 cMorgans. Isoforms of WSP-2 possessed similar pIs to that of WSP-3 and overlapping bands were observed in the gels. These bands segregated independently in F2 and doubled haploid populations, implying two unlinked genes. All three loci were found to be polymorphic: two alleles were detected at the Wsp-2 locus, three at Wsp-3 and two at β-Amy-1. The frequency of alleles at all three loci was found to be different in winter and spring genotypes. Spring genotypes possessed a wider range of phenotypes than winter genotypes. Spring and winter genotypes could be distinguished on the basis of WSP-3 and β- AMY-1 phenotypes. The linkage between Wsp-3 and β-Amy-1 loci and genes controlling spring/winter habit on chromosome 4H is discussed. It is concluded that Wsp-3 and β-Amy-1 can be used as genetic markers for spring/winter habit in barley genetic research and breeding.