The Salicylic Acid Signaling Pathway Plays an Important Role in the Resistant Process of Brassica rapa L. ssp. pekinensis to Plasmodiophora brassicae Woronin

Clubroot disease, caused by Plasmodiophora brassicae Woronin infection, leads to significant yield and economic losses in cruciferous vegetables. However, the molecular mechanism underlying the interaction between P. brassicae and Chinese cabbage (Brassica rapa L. ssp. pekinensis) remains unknown. In this study, two-dimensional electrophoresis was used to screen differentially expressed proteins (DEPs) in clubroot-diseased and control roots of Chinese cabbage. A total of 21 DEPs changed by more than twofold in the diseased roots, of which 16 were successfully identified using matrix-assisted laser desorption/ionization-time of flight/mass spectrometry. Quantitative real-time polymerase chain reactions’ analysis showed that most of the 16 candidate genes had the consistent transcription and protein level expression. Gene ontology analysis revealed that 10 out of 16 candidate genes responded to stimulus. Two of these genes were involved in the salicylic acid (SA) signaling pathway. The content of SA and the expression of genes in the SA signaling pathway were altered in the diseased roots and disease resistance increased after SA treatment. Thus, the interactions between Chinese cabbage and P. brassicae stimulate the SA signaling pathway. Our findings may contribute to improving clubroot resistance in Chinese cabbage.