Construction of genetic linkage map and QTL analysis of Phytophthora infestans resistant gene Ph-2 in tomato.

In this paper,a set of 260 F2 progeny was obtained by crossing the Phytophthora infestans resistant cultivar W.Va 700(Solanum lycopersicum var.cerasiforme) carrying Ph-2 gene(resistant to race T1) with the susceptible cultivar line 04957(S.lycopersicum) for constructing the genetic map,and plants were inoculated using Phytophthora infestans T1 for disease resistance identification.The results showed that the resistance to race T1 was in accordance with normal distribution,and the resistance of Ph-2 gene was quantitative character:A genetic map with 12 linkage groups was constructed by RAPD,SSR and AFLP methods.The map covered 1 154.85 cM map distance,the average map distance was 9.47 cM.Five QTL(quantitative trait loci),designed as QPh2-1,QPh2-2,QPh2-3 and QPh2-4,were linked to Ph-2 gene in the third linkage group.The explainable phenotypic variation of them were 26.95%,16.63%,16.24% and 6.69% respectively.QPh2-5 was detected on chromosome 1,it was 0.76 cM away from molecular marker OPK14,its explainable phenotypic variation was 33.87%.The genetic effects of QPh2-1 and QPh2-5 were additive and dominant seperately.