Molecular cloning of PbSTKL1 gene from Plasmodiophora brassicae expressed during clubroot development

Infection of crucifers by the obligate plant pathogen Plasmodiophora brassicae Woron. results in the formation of clubroot disease in these plants. Plasmodiophora brassicae gene expression during disease development was studied by differential display analysis of total RNA extracted from the roots of Chinese cabbage inoculated with the pathogen. In a series of experiments, 30 differentially expressed bands of cDNA were detected, and the expression of clone no. 17 was confirmed in clubbed roots. Southern blot analysis showed that this clone was a single-copy gene in the P. brassicae genome. Putative amino acid sequence analysis of the full-length cDNA of clone no. 17 (4.6 kb, designated PbSTKL1) revealed a serine/threonine kinase-like domain at the C-terminal region and a coiled-coil structure in the middle region of the putative protein. PbSTKL1 expression increased strongly beginning 30 days after inoculation and was coincident with resting spore formation.