A nucleotide sequence linked to the vrs1 locus for studies of differentiation in cultivated barley (Hordeum vulgare L.).

A PCR-amplified DNA, cMWG699, is linked to the vrs1 (formerly v) locus controlling 2- and 6-rowed spikelets. Restriction analysis of the amplified DNA of 65 varieties from Europe, America, and East Asia revealed 3 alleles, named types K, A and D. Two-rowed varieties were mostly of type K allele, and 6-rowed varieties were mostly of type A allele. The type D allele was found only in three 6-rowed varieties. Sequence comparison of these alleles revealed that the type A allele is more closely related to the type K allele than to the type D allele. The sequence analysis also suggested that the types A and D alleles diverged earlier than when 6-rowed barley arose. On the assumption that 2-rowed barleys were the ancestors of 6-rowed barley, 6-rowed barleys with types A and D alleles probably differentiated from 2-rowed barleys with type A and D alleles, respectively, by independent mutations on the vrs1 locus.