Pathogen corruption and site-directed recombination at a plant disease resistance gene cluster

• Published in: Genome Research Vol. 18; no. 12; pp. 1918 - 1923
• Main Authors: Nagy, Ervin D, Bennetzen, Jeffrey L
• Format: Journal Article
• Language: English
• Published: United States Cold Spring Harbor Laboratory Press 01.12.2008
• Subjects: Ascomycota - pathogenicity; DNA, Plant - genetics; DNA, Plant - isolation & purification; Gene Library; Gene Rearrangement; Genes, Plant; Immunity, Innate; Letter; Multigene Family; Mutagenesis, Site-Directed; Periconia; Plant Diseases - genetics; Recombination, Genetic; Sequence Analysis, DNA; Sorghum; Sorghum - genetics; Sorghum - metabolism; Sorghum bicolor
• ISSN: 1088-9051; 1549-5469; 1549-5477
• DOI: 10.1101/gr.078766.108

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.