Marker-Assisted Pyramiding of Genes for Multilocular Ovaries, Self-Compatibility, and Clubroot Resistance in Chinese Cabbage (<i>Brassica rapa</i> L. ssp. <i>pekinensis</i>)

Abstract

Molecular marker-assisted gene pyramiding combined with backcrossing has been widely applied for crop variety improvement. Molecular marker identification could be used in the early stage of breeding to achieve the rapid and effective pyramiding of multiple genes. To create high-quality germplasm for Chinese cabbage breeding, multi-gene pyramiding for self-compatibility, multilocular, and clubroot resistance was performed through molecular marker-assisted selection. The results showed that self-compatibility and multilocular traits were controlled by a pair of recessive genes. Two flanking markers, sau_um190 and cun_246a, and marker Teo-1, based on the gene sequence related to multilocular ovaries, were used for multilocular ovary trait selection. Two flanking markers, SCF-6 and SC-12, and marker Sal-SLGI /PK1+PK4, based on the gene sequence, were used for self-compatibility selection. Two flanking markers, TCR74 and TCR79, closely linked to clubroot resistance gene CRb, were used as foreground selection markers. Based on Chinese cabbage genomic information, 111 SSR markers covering 10 chromosomes were applied for background selection. After multiple generations of selection, a multi-gene pyramided line from a BC4F2 population with self-compatibility, multilocular ovaries, and clubroot resistance was obtained with a high genomic background recovery rate. The improved pyramided line is expected to be utilized as a potential material in further breeding programs.

Keywords

• <i>Brassica rapa</i>
• gene pyramiding
• marker-assisted selection