| Abstract: | ![]()
Clubroot is a prevailing soil-borne disease affecting rapeseed production worldwide. However, few clubroot resistant rapeseed accessions were available for breeding. Identification and introgression of new clubroot resistant genes from closely related species by distant hybridization is an effective strategy. In the present study, 9 radish（Raphanus sativus L., 2 n=18, RR） lines resistant to Plasmodiophora brassicae pathotype 4 were used as donors to transfer clubroot resistance into a susceptible rapeseed（Brassica napus L., 2 n=38, AACC） line by distant hybridization combined with embryo rescue. Nine intergeneric crosses were made but only 1（411 × 93039） produced F1 plants both from embryo rescue and natural seed-setting. Authenticity of triploid F1 hybrids（2 n= 28, ACR） were verified by flower color, cytological observation and molecular marker analysis, and 2 genuine F1 hybrids were identified. After chromosome doubling, these synthetic allohexaploid plants（2 n=56, AACCRR） became partially fertile（pollen viability rate = 35%） and were backcrossed with rapeseed parent to generate a BC1 population（2 n=47, AACCR）. Totally 178 BC1 plants were obtained, of which the majority（96.1%） were resistant to clubroot. These backcrossing progenies could be used for the breeding of new rapeseed varieties resistant to clubroot. |
