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QTL Mapping of Fruit Rot Resistance to the Plant Pathogen Phytophthora capsici in a Recombinant Inbred Line Capsicum annuum Population

May 2014 , Volume 104 , Number  5
Pages  479 - 483

R. P. Naegele, H. Ashrafi, T. A. Hill, S. Reyes Chin-Wo, A. E. Van Deynze, and M. K. Hausbeck

First and sixth authors: Department of Plant, Soil and Microbial Sciences, Michigan State University East Lansing 48824; and second, third, fourth, and fifth authors: Seed Biotechnology Center, University of California, Davis 95616.

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Accepted for publication 14 October 2013.

Phytophthora capsici is an important pepper (Capsicum annuum) pathogen causing fruit and root rot, and foliar blight in field and greenhouse production. Previously, an F6 recombinant inbred line population was evaluated for fruit rot susceptibility. Continuous variation among lines and partial and isolate-specific resistance were found. In this study, Phytophthora fruit rot resistance was mapped in the same F6 population between Criollo del Morelos 334 (CM334), a landrace from Mexico, and ‘Early Jalapeno’ using a high-density genetic map. Isolate-specific resistance was mapped independently in 63 of the lines evaluated and the two parents. Heritability of the resistance for each isolate at 3 and 5 days postinoculation (dpi) was high (h2 = 0.63 to 0.68 and 0.74 to 0.83, respectively). Significant additive and epistatic quantitative trait loci (QTL) were identified for resistance to isolates OP97 and 13709 (3 and 5 dpi) and 12889 (3 dpi only). Mapping of fruit traits showed potential linkage with few disease resistance QTL. The partial fruit rot resistance from CM334 suggests that this may not be an ideal source for fruit rot resistance in pepper.

© 2014 The American Phytopathological Society