High-throughput sequencing reveals tuber mustard genes responsive to Plasmodiophora brassicae in the early stage of infection

Tuber mustard is a kind of Brassica crop, swollen stem of this crop is the material of mustard pickle, which has high economic value. Clubroot is a serious disease of brassicaceae plants, causing huge losses every year. Although some clubroot resistant cultivars of tuber mustard were bred, the mechanism by which tuber mustard responds to the pathogen Plasmodiophora brassicae needs to be elucidated. Morphologic and cytological changes of tuber mustard roots were observed during the pathogenetic process, and 72 h after inoculation was found to be the key stage of the interaction between the root of tuber mustard and the pathogen. A transcriptome sequencing was performed using the roots inoculated and mock-inoculated by P. brassicae at 72 h. A total of 2294 up -regulated and 6533 down-regulated genes were identified, and the expression levels of 11 differentially expressed genes were verified by qPCR. Genes related to MAPK signaling pathway-plant, plant hormone signal transduction, phenylpropanoid biosynthesis, nitrogen metabolism, ABC transporters, plant-pathogen interaction were involved in tuber mustard response to infection by P. brassicae. After the pathogen inoculation, among the differentially expressed genes, most of the PR1 like genes were upregulated, while most of BAK1 like genes, MAPK like genes, SUMM2 like genes, JAZ like genes, and NPR1 like genes were downregulated. The miRNA sequencing results showed that miR160a-5p, miR319a, miR395i, miR400 and their relative targets were nega-tively co-expressed, which might be involved in the regulation of tuber mustard response to the pathogen. This study is helpful for further studying the functions of tuber mustard genes during P. brassicae infection.