Genetic Mapping of Resistant Genes in Brassica pekinensis Against Plasmodiophora brassicae Race 6

Abstract

Inbred lines of Chinese cabbage KU-101 (resistant line against Plasmodiophora brassicae race 6) and CS-113 (susceptible line) were crossed and their progeny lines F1, BC1F1, F2, and F3 were produced for the construction of the genetic linkage map of P. brassicae race 6- resistant Brassica campestris ssp. pekinensis genome. Restriction fragment length polymorphism (RFLP) was applied to compare between parents and their F2 progenies with a total of 192 probes and 5 restriction enzymes. The constructed RFLP map covered 1,104 cM with a mean distance between genetic marker of 8.0 cM, and produced 10 linkage groups having 121 genetic loci. The loci of P. brassicae race 6 (CR6)-resistant Brassica genome were determined by interval mapping of quantitative trait loci (QTL), which resulted from bioassay using the same race of the fungi in F3 population. Resistant loci were estimated in numbers 1 (G1) and 3 (G3) linkage groups. In the regression test, G1 had a value of 4.8 logarithm of odd (LOD) score, while G3 had values of 4.2-7.2. Given these results, the location of the CR6-resistant loci within the Brassica genome map can now be addressed.