Improving Clubroot Resistance of Cabbage Cultivar 'xiyuan 4' by Foreground Marker Assisted Selection and Whole-Genome Re-Sequencing Background Assisted Selection.

Cabbage is severely threatened by clubroot disease worldwide. To improve the clubroot resistance of cabbage, clubroot resistance from ‘9LQ18-5’ was introgressed into the susceptible parent ‘F416’ of commercial cabbage variety ‘Xiyuan 4’. During the backcrossing program, clubroot resistant individuals were selected by CCR1 and CCR2 markers, whereas the background of backcrossing progenies was detected by whole genome re-sequencing in BC3F1 individuals. Among them, 21 − 9 with the highest recurrent parent genomic recovery (83.93