QTL Analysis for Resistance to Phytophthora Blight (Phytophthora capsici Leon.) Using an Intraspecific Doubled-Haploid Population of Capsicum annuum
Sugita. T Sugimura. Y Nagata. R Yamaguchi. K Kinoshita. T Yuji. K Kawasaki. S Todoroki. A
Breeding Science ; 2006 [Vol.56] Pages:137-145
Abstract
A doubled-haploid (DH) population (n = 176) obtained by anther culture of an F1 hybrid between a line susceptible to Phytophthora capsici K9-11 (Capsicum annuum L.) and a line resistant to P. capsici AC2258 (C. annuum L.) was inoculated with P. capsici. QTL analysis of the resistance was performed using a linkage map consisting of 16 linkage groups (LGs), covering a total distance of 1100.5 cM. Three QTLs were detected on LG1, LG6 and LG7. The QTL with the highest LOD score, detected on LG7, explained 82.7% of the phenotypic variance with a LOD score of 67.02. This QTL was designated as Phyt-1. The nearest marker was an AFLP marker, M10E3-6. The second QTL, designated as Phyt-2, was found on LG1. It explained 6.4% of the phenotypic variance with a LOD score of 2.54. The nearest RAPD marker was RP13-1. The other QTL, designated as Phyt-3, which was found on LG6, explained 5.6% of the phenotypic variance with a LOD score of 2.20. The nearest AFLP marker was M9E3-11. It was confirmed that the lines with a high resistance could be efficiently selected by using two markers, M10E3-6 and RP13-1, simultaneously. The presence of both Phyt-1 and Phyt-2 under homozygous conditions may enable to breed resistant cultivars of sweet pepper. The molecular markers identified in the present study could be useful for marker-assisted selection (MAS) in order to breed sweet pepper cultivars with a high resistance to P. capsici using AC2258 as a source of resistance genes.
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