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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #191683
Title: MAPPING AND CHARACTERIZATION OF THE SORGHUM PC GENE: A HOST RESISTANCE GENE CORRUPTED TO ASSIST INFECTION BY A FUNGAL NECROTROPH

Author
item NAGY, E - UNIVERSITY OF GEORGIA
item LEE, T - PURDUE UNIVERSITY
item CHENG, C - PURDUE UNIVERSITY
item Dunkle, Larry

Submitted to: Maize Genetics Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/2006
Publication Date: 3/9/2006
Citation: Nagy, E.D., Lee, T.C., Cheng, C.P., Dunkle, L.D. 2006. Mapping and characterization of the sorghum pc gene: a host resistance gene corrupted to assist infection by a fungal necrotroph. Maize Genetics Conference Abstracts.p. 132.

Interpretive Summary:

Technical Abstract: Several pathogenic fungi secrete phytotoxins that selectively affect specific host plant genotypes. Although our understanding of plant-microbe interactions has increased tremendously in recent years, little is known about host-selective toxin resistance genes in plants. In contrast to the ‘gene-for-gene’ type resistance genes, which are structurally similar to each other, the known toxin resistance genes are highly variable in their genetic properties. The pc gene confers resistance against root and crown rot in sorghum caused by the soil-borne fungus PERICONIA CIRCINATA. The Pc gene is genetically unstable, generating recessive toxin-resistant alleles (pc) at a meiotic rate of about 1 in 4000. A high-density genetic map including the Pc locus was constructed using an RFLP marker and 18 newly generated PCR-based markers. The Pc gene was confined to a 0.9 cM segment, corresponding to about 100 kb on the physical map. This region was sequenced and seven gene candidates were identified. Isogenic wild type and Pc to pc mutant sorghum lines were screened using single stranded conformational polymorphism (SSCP) to detect mutations in the gene candidates. The SSCP analysis revealed a decrease in the copy number of a tandem duplicated NBS-LRR gene in the pc mutant lines as compared to the wild type lines. All other genes were identical between the isogenic lines. Frequent unequal recombinations resulting in copy number variations have been reported for other tandem duplicated NBS-LRR genes. The data suggest that the loss of functional NBS-LRR gene copies provides peritoxin resistance in sorghum. These findings suggest a novel virulence strategy, wherein plant pathogens exploit the host defense system to disrupt and invade plant tissues.