Linkage relationships of ten powdery mildew resistance genes on barley chromosome 5

Abstract

The linkage relationships between 10 powdery mildew resistance genes positioned in or closely linked to, Ml-a or Ml-k loci on barley chromosome 5 were examined. No recombination was obtained between the Ml-a genes examined. The genes Ml-a(Ar) and Ml-a(Rul) were shown to be different from the 11 previously identified Ml-a genes and it is proposed that they be called Ml-a12 and Ml-a13 respectively. An additional gene was discovered in barley line ‘Is0 20R’ and is named Ml-a14. The gene symbols Ml-k and Ml-a4 appear to represent an identical gene in the Ml-k locus and it is suggested that only the symbol Ml-k be used in future. The gene Ml-(Ru2) was found to be inherited independently of the genes Ml-a and Ml-k. Linkage estimates between gene Ml-k and seven Ml-a genes ranged from 5.4 to 10.6 per cent recombination.