Mapping genes of Solanum caripense involved in resistance to Phytophthora infestans, the causal agent of potato late blight
Trognitz. F Trognitz. B
Genetic Variation for Plant Breeding ; 2004 [Vol.] Pages:249-253
Abstract
Reciprocal, bi-parental cross progenies of Solanum caripense, a diploid (2n = 2x = 24), self-incompatible, non-tuberizing, wild herb occurring throughout the Andes from Bolivia to Costa Rica, were used for the construction of parental framework linkage maps. Unexpectedly, low levels of polymorphism were encountered. The map of crp-1 comprises in total 287 cM and contains 89 markers in 10 linkage groups, whereas the map of crp-4 spans a genetic distance of 310 cM distributed over 66 markers in 12 l inkage groups. Gene-specific markers detecting R gene analogs, a kinase similar to the tomato Pto gene, and a homolog of SGT1 were also mapped. Two QTLs associated with resistance were
located on the parental linkage maps by composite interval analysis of marker-trait associations. Within the cytoplasmic background of parent crp-4, a portion of the susceptible progenies carried the marker alleles for resistance at the position of the QTLs. This suggested that resistance may have been abrogated by an additional, independent nuclear factor that interacts with the cytoplasm of parent crp-4 to cause a susceptible phenotype. By single-marker analyses of marker-trait association, three additional marker loci independent of the QTLs were detected that significantly contributed to the resistance phenotype. S. caripense, a wild plant that has not been subjected to domestication and breeding should be a valuable source of resistance to late blight.
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