Transcriptome Analysis of a Highly Resistant Chinese Cabbage Variety in Response to Plasmodiophora brassicae during Early and Late Stages of Root Hair Infection

摘要

Plasmodiophora brassicae (P. brassicae) is widely distributed in the field. To understand the early and late defense responses induced by P. brassicae infection in Brassica rapa, RNA-Seq was used to perform high-throughput transcriptome analysis of roots of a highly resistant Chinese cabbage variety that does not form root galls. There are totally 153 and 99 differentially expressed genes (DEGs) between inoculated and healthy roots at 4 and 10 days post inoculation (dpi), respectively. The functions of the DEGs were annotated. Data showed that most DEGs were involved in metabolic processes, cell wall modification, peroxidase activity, signal transduction and defense. There were 71 DEGs associated with plant–pathogen interactions, including genes associated with hormone signalling, pathogenesis, peroxidase, oxidoreductase, chitinase, cell wall modification, and trehalose biosynthetic and metabolic processes. The expression levels of resistance proteins and pathogenesis-related (PR) genes mediated by salicylic acid (SA) were high in the inoculated roots, especially at 4 dpi, suggesting that SA signalling during early infection was important for resistance to P. brassicae in this highly resistant Chinese cabbage variety. These results provide theoretical basis for studying the molecular mechanism of clubroot resistance.