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.