Identification of isolate-specific resistance QTLs to phytophthora root rot using an intraspecific recombinant inbred line population of pepper (Capsicum annuum)

• Published in: Plant pathology 2012-02, Vol.61 (1), p.48-56
• Main Authors: Truong, H. T. H., Kim, K. T., Kim, D. W., Kim, S., Chae, Y., Park, J. H., Oh, D. G., Cho, M. C.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Classical genetics, quantitative genetics, hybrids; common QTL; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Genetics of eukaryotes. Biological and molecular evolution; isolate; isolate-specificity; Phytopathology. Animal pests. Plant and forest protection; Phytophthora capsici; resistance genes
• ISSN: 0032-0862; 1365-3059
• DOI: 10.1111/j.1365-3059.2011.02483.x

Quantitative trait loci (QTL) for resistance to phytophthora root rot caused by Phytophthora capsici were investigated using two Korean P. capsici isolates and 126 F8 recombinant inbred lines derived from a cross of Capsicum annuum line YCM334 (resistant parent) and local cv. Tean (susceptible parent). The experimental design was a split plot with two replications. Highly significant effects of pathogen isolate, plant genotype, and genotype × isolate were detected. QTL mapping was performed using a genetic linkage map covering 1486·6 cM of the pepper genome, and consisted of 249 markers including 136 AFLPs (Amplified Fragment Length Polymorphisms), 112 SSRs (Simple Sequence Repeats) and one CAPS (Cleaved Amplified Polymorphic Sequence). Fifteen QTLs were detected on chromosomes 5 (P5), 10 (P10), 11 (P11), Pb and Pc using two data processing methods: percentage of wilted plants (PWP) and relative area under the disease progress curves (RAUDPC). The phenotypic variation explained by each QTL (R2) ranged from 6·0% to 48·2%. Seven QTLs were common to resistance for the two isolates on chromosome 5 (P5); six were isolate‐specific for isolate 09‐051 on chromosomes 10 (P10) and Pc, and two for isolate 07‐127 on chromosomes 11 (P11) and Pb. The QTLs in common with the major effect on the resistance for two isolates explained 20·0–48·2% of phenotypic variation. The isolate‐specific QTLs explained 6·0–17·4% of phenotypic variation. The result confirms a gene‐for‐gene relationship between C. annuum and P. capsici for root rot resistance.