Specific Genes Identified in Pathotype 4 of the Clubroot Pathogen Plasmodiophora brassicae

Clubroot is an important disease of cruciferous crops caused by Plasmodiophora brassicae, and pathotypes are classified based on the response of differential hosts. This study was conducted to identify genetic markers able to differentiate pathotypes. Differential expression of genes between pathotype 4 (P4) and pathotype 7 (P7) was assessed according to transcriptome data of molecular marker screening. Among the pathotypes (P2, P4, P5, P7, P9, P10, and P11) tested, six genes were exclusive to P4, dividing the isolates into three types: PBRA_003263 and PBRA_003268 were present in all P4 isolates, PBRA_000003/Novel512 were found in a type of P4 (P4-1), and Novel137/PBRA_005772 were found in another P4 type, P4-2. Amplicons for all six genes were produced for only one isolate, which we named P4-3. This study is the first to establish a molecular identification system for P4 the, predominant pathotype in China. The genes identified might serve as molecular markers for differentiation of P4 from other pathotypes and may also distinguish different types of P4.

Characterization of Five Molecular Markers for Pathotype Identification of the Clubroot Pathogen Plasmodiophora brassicae

Clubroot disease is an important disease on cruciferous crops caused by Plasmodiophora brassicae infections. The pathotypes have been classified based on the reactions of differential hosts. However, molecular markers of particular pathotypes for P. brassicae are limited. In this study, we found five genetic markers in association with different pathotypes. Different gene expression patterns among different pathotypes (P4, P7, P9, and P11) were assayed according to the transcriptome data. The assay indicated that molecular markers PBRA_007750 and PBRA_009348 could be used to distinguish P11 from P4, P7, and P9; PBRA_009348 and Novel342 could distinguish P9 from P4, P7, and P11; and PBRA_008439 and Novel342 could represent a kind of P4. Polymerase chain reaction cycles ranging from 25 to 30 were able to identify the predominant pathotype in general. Therefore, these molecular markers would be a valuable tool to identify and discriminate pathotypes in P. brassicae population.