A barley gene family homologous to the maize rust resistance gene Rp1-D.

Many characterized plant disease resistance genes encode proteins which have conserved motifs such as the nucleotide binding site. Conservation extends across different species, therefore resistance genes from one species can be used to isolate homologous regions from another by employing DNA sequences encoding conserved protein motifs as probes. Here we report the isolation and characterization of a barley ( Hordeum vulgare L.) resistance gene analog family consisting of nine members homologous to the maize rust resistance gene Rp1-D. Five barley Rp1-D homologues are clustered within approximately 400 kb on chromosome 1(7H), near, but not co-segregating with, the barley stem rust resistance gene Rpg1; while others are localized on chromosomes 3(3H), 5(1H), 6(6H) and 7(5H). Analyses of predicted amino-acid sequences of the barley Rp1-D homologues and comparison with known plant disease resistance genes are presented.