Identification and Characterization of Crr1a, a Gene for Resistance to Clubroot Disease (Plasmodiophora brassicae Woronin) in Brassica rapa L.

Abstract

Clubroot disease, caused by the obligate biotrophic protist Plasmodiophora brassicae Woronin, is one of the most economically important diseases of Brassica crops in the world. Although many clubroot resistance (CR) loci have been identified through genetic analysis and QTL mapping, the molecular mechanisms of defense responses against P. brassicae remain unknown. Fine mapping of the Crr1 locus, which was originally identified as a single locus, revealed that it comprises two gene loci, Crr1a and Crr1b. Here we report the map-based cloning and characterization of Crr1a, which confers resistance to clubroot in Brassica rapa. Crr1aG004, cloned from the resistant line G004, encodes a Toll-Interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat (TIR-NB-LRR) protein expressed in the stele and cortex of hypocotyl and roots, where secondary infection of the pathogen occurs, but not in root hairs, where primary infection occurs. Gain-of-function analysis proved that Crr1aG004 alone conferred resistance to isolate Ano-01 in susceptible Arabidopsis and B. rapa. In comparison, the susceptible allele Crr1aA9709 encodes a truncated NB-LRR protein, which lacked more than half of the TIR domain on account of the insertion of a solo-long terminal repeat (LTR) in exon 1 and included several substitutions and insertion-deletions in the LRR domain. This study provides a basis for further molecular analysis of defense mechanisms against P. brassicae and will contribute to the breeding of resistant cultivars of Brassica vegetables by marker-assisted selection.Data deposition The sequence reported in this paper has been deposited in the GenBank database (accession no. AB605024).

Transcriptome Analysis of Arabidopsis thaliana in Response to Plasmodiophora brassicae during Early Infection

“…The response of some receptor kinase genes to P. brassicae infection has been reported (Ueno et al, 2012; Hatakeyama et al, 2013). We also found that many receptor kinase genes are differentially expressed at 24 and 48 hpi (Figure S7).…”

Genome resequencing and comparative variome analysis in a Brassica rapa and Brassica oleracea collection

“…Further studies reported the phenomenon of sub-genome dominance among the three sub-genomes in Brassica s 8,9 , and found that the biased distribution of small RNA-targeted TEs plays an important role in this phenomenon 11,12 . Furthermore, the release of the genome sequences has also contributed to the mapping, cloning and functional studies of agronomic genes in Brassica crops, such as two clubroot resistance genes 13,14 , two blackleg resistance genes 15,16 , as well as two key genes regulating the time of flowering 17–19 . The availability of these reference genomes also made it possible to build variome datasets by resequencing populations of B. rapa and B. oleracea , to investigate domestication of the diverse morphotypes.…”

Discovery of clubroot-resistant genes in Brassica napus by transcriptome sequencing

“…Manzanares-Dauleux et al (2000) mapped clubroot-resistant gene Pb-Bn1 on the linkage group using DH group from the hybrid between B. napus Darmor-bzh and Yudal. By using map-based cloning technology, Hatakeyama et al (2013) identified gene Crr1, which encodes a TIR-NBS-LRR protein, with clubroot-resistance function.…”