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Updated: Jul 2, 2026

High-Throughput Identification of Resistance to Pseudomonas syringae pv. Tomato in Tomato using Seedling Flood Assay
Published on: March 10, 2020
Pathogen corruption and site-directed recombination at a plant disease resistance gene cluster
Ervin D Nagy1, Jeffrey L Bennetzen
1Department of Genetics, University of Georgia, Athens, Georgia 30602, USA.
Abstract:
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.
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