Comparative genomic analysis of sequences around the Rdr1 locus in resistant and susceptible rose genotypes.

摘要

Sequence analysis of the locus carrying the Rdr1 gene conferring resistance to the black spot disease in roses was conducted. A 204-b and 249-b sequence from the resistant Rosa multiflora and susceptible Rosa rugosa loci, respectively, were compared to understand the mechanism involved in the diversification of the Rdr1 gene cluster. Sequence similarity between the nine Rdr1 paralogues of R. multiflora and 11 orthologues of R. rugosa up to 99% was observed. In some cases the similarity was higher among the Rdr1 orthologues than among the paralogues. Recombination, gene conversion and point mutation events were detected within the Rdr1 orthologues. The analysis showed that similar R gene diversifying mechanisms would take place in woody perennial rose plants as already indicated for herbaceous annuals. In relation to the R genes in annual plants, recent duplications might have generated the Rdr1 gene cluster in rose plants.