Quantitative Trait Locus Mapping of Clubroot Resistance and <i>Plasmodiophora brassicae</i> Pathotype Banglim-Specific Marker Development in <i>Brassica rapa</i>

• Main Authors: Su Ryun Choi, Sang Heon Oh, Sushil Satish Chhapekar, Vignesh Dhandapani, Chang Yeol Lee, Jana Jeevan Rameneni, Yinbo Ma, Gyung Ja Choi, Soo-Seong Lee, Yong Pyo Lim
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: International Journal of Molecular Sciences
• Subjects: clubroot disease; resistance mapping; quantitative trait loci (QTL); marker; <i>Brassica rapa</i>
• Online Access: https://www.mdpi.com/1422-0067/21/11/4157

Clubroot resistance is an economically important trait in Brassicaceae crops. Although many quantitative trait loci (QTLs) for clubroot resistance have been identified in <i>Brassica</i>, disease-related damage continues to occur owing to differences in host variety and constant pathogen variation. Here, we investigated the inheritance of clubroot resistance in a double haploid population developed by crossing clubroot resistant and susceptible lines “09CR500” and “09CR501”, respectively. The resistance of “09CR500” to <i>Plasmodiophora brassicae</i> pathotype “Banglim” was controlled as a single dominant gene, with the segregation of resistance and susceptibility being nearly 1:1. <i>PbBrA08^Banglim</i> was identified as having a logarithm of odds value of 7.9–74.8, and a phenotypic variance of 26.0–97.1% with flanking marker “09CR.11390652” in A08. After aligning QTL regions to the <i>B. rapa</i> reference genome, 11 genes were selected as candidates. <i>PbBrA08^Banglim</i> was located near <i>Crr1</i>, <i>CRs</i>, and <i>Rcr9</i> loci, but differences were validated by marker analysis, gene structural variations, and gene expression levels, as well as phenotypic responses to the pathotype. Genotyping using the “09CR.11390652” marker accurately distinguished the Banglim-resistance phenotypes in the double haploid population. Thus, the developed marker will be useful in <i>Brassica</i> breeding programs, marker-assisted selection, and gene pyramiding to identify and develop resistant cultivars.