Introgression of clubroot resistance into an elite pak choi inbred line through marker-assisted introgression breeding

摘要

Clubroot is a soilborne disease that severely infects cruciferous species. Pak choi (Brassica rapa subsp. chinensis) is an economically important cruciferous crop cultivated throughout the world. However, no clubroot-resistant germplasms have been identified in pak choi to date. To improve disease resistance, we used marker-assisted selection (MAS) to introgress the clubroot resistance (CR) trait from the CCR13685' Chinese cabbage (B.rapa subsp.pekinensis) inbred line into an elite pak choi inbred line, GHQ11021'. Genetic analysis of F-2 and BC1 progeny showed that CR of CCR13685' was controlled by a single dominant gene. We designed nine candidate sequence-characterized amplified region markers, K-1 to K-9, based on two molecular markers linked to the CR gene. We found that K-3 co-segregated with CR and an inoculation test confirmed that K-3 could be used for MAS. Two introgression lines, BC3-1-4 and BC3-2-18, were developed using K-3 for foreground selection. These lines displayed the same phenotypic properties as GHQ11021', but were highly resistant to clubroot, indicating that the CR gene of CCR13685' had been successfully introduced into pak choi.