Cloning and molecular characterization of three members of the NBS-LRR subfamily located in the vicinity of the Co-2 locus for anthracnose resistance in Phaseolus vulgaris.
Co-2 is one of the R-genes against anthracnose identified in common bean. A RAPD marker, cloned as PvH20, was previously shown to contain 6 imperfect leucine-rich-repeats and to reveal a family of related sequences in the vicinity of the Co-2 locus. Using PvH20 as probe, a genomic clone and 2 partial cDNAs were isolated. DNA sequencing revealed that the 6.1 kb genomic fragment contains sequences encoding both NBS-LRR (ORF1) and kinase-like (ORF2) products. The 2 partial cDNAs (cD7 and cD8) belong to the NBS-LRR subfamily as do most of the resistance genes cloned to date. The LRR domain of ORF1 is interrupted by 2 stop codons suggesting that it corresponds to a non-functional member of the multigene family and ORF2 appears to be a kinase pseudogene. The 3 NBS-LRR polypeptides share a high level of amino acid identity and represent different members of a related family. By genetic mapping ORF1, cD7, and cD8 were found to span a genetic distance of 3 cM: cD8 maps at 2 cM from Co-2 and 3 cM from ORF1, cD7 maps at 1 cM from ORF1 and co-segregates with Co-2, thus cD7 might be a putative candidate for the Co-2 R-gene.
Creusot
F
F
Université Paris-Sud, CNRS UMR 8618, ORSAY, France. creusot@lovelace.infobiogen.fr
Macadré
C
C
Ferrier Cana
E
E
Riou
C
C
Geffroy
V
V
Sévignac
M
M
Dron
M
M
Langin
T
T
D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018744:DNA, Plant; D007887:Fabaceae / Q000235:genetics*; D017343:Genes, Plant; D000090263:Leucine-Rich Repeat Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D010946:Plants, Medicinal; D011506:Proteins / Q000235:genetics*
D018744:DNA, Plant; D000090263:Leucine-Rich Repeat Proteins; D011506:Proteins