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A Novel Capsicum Gene Inhibits Host-Specific Disease Resistance to Phytophthora capsici

May 2013 , Volume 103 , Number  5
Pages  472 - 478

Gregory Reeves, Ariadna Monroy-Barbosa, and Paul W. Bosland

First and third authors: Department of Plant and Environmental Sciences, New Mexico State University, Las Cruces, NM 88003; and second author: Clause Seed Co., 5820 Research Way, Immokalee, FL 34142.

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Accepted for publication 20 December 2012.

A novel disease resistance inhibitor gene (inhibitor of P. capsici resistance [Ipcr]), found in the chile pepper (Capsicum annuum) variety ‘New Mexico Capsicum Accession 10399’ (NMCA10399), inhibits resistance to Phytophthora capsici but not to other species of Phytophthora. When a highly P. capsici-resistant variety was hybridized with NMCA10399, the resultant F1 populations, when screened, were completely susceptible to P. capsici for root rot and foliar blight disease syndromes, despite the dominance inheritance of P. capsici resistance in chile pepper. The F2 population displayed a 3:13 resistant-to-susceptible (R:S) ratio. The testcross population displayed a 1:1 R:S ratio, and a backcross population to NMCA10399 displayed complete susceptibility. These results demonstrate the presence of a single dominant inhibitor gene affecting P. capsici resistance in chile pepper. Moreover, when lines carrying the Ipcr gene were challenged against six Phytophthora spp., the nonhost resistance was not overcome. Therefore, the Ipcr gene is interfering with host-specific resistance but not the pathogen- or microbe-associated molecular pattern nonhost responses.

Additional keywords: host resistance, susceptibility factor.

© 2013 The American Phytopathological Society