Pathogen corruption and site-directed recombination at a plant disease resistance gene cluster.
The Pc locus of sorghum (Sorghum bicolor) determines dominant sensitivity to a host-selective toxin produced by the fungal pathogen Periconia circinata. The Pc region was cloned by a map-based approach and found to contain three tandemly repeated genes with the structures of nucleotide binding site-leucine-rich repeat (NBS-LRR) disease resistance genes. Thirteen independent Pc-to-pc mutations were analyzed, and each was found to remove all or part of the central gene of the threesome. Hence, this central gene is Pc. Most Pc-to-pc mutations were associated with unequal recombination. Eight recombination events were localized to different sites in a 560-bp region within the approximately 3.7-kb NBS-LRR genes. Because any unequal recombination located within the flanking NBS-LRR genes would have removed Pc, the clustering of cross-over events within a 560-bp segment indicates that a site-directed recombination process exists that specifically targets unequal events to generate LRR diversity in NBS-LRR loci.
Nagy
Ervin D
ED
Department of Genetics, University of Georgia, Athens, Georgia 30602, USA.
Bennetzen
Jeffrey L
JL
D001203:Ascomycota / Q000472:pathogenicity*; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D015723:Gene Library; D015321:Gene Rearrangement; D017343:Genes, Plant; D007113:Immunity, Innate; D005810:Multigene Family; D016297:Mutagenesis, Site-Directed; D010935:Plant Diseases / Q000235:genetics*; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D045868:Sorghum / Q000235:genetics / Q000378:metabolism
D018744:DNA, Plant