Research On The Interaction Mechanism Of Salicylic Acid And Chinese Cabbage Plasmodiophora Brassicae

Salicylic acid (SA) defense signaling pathway plays an important role in defense mechanisms of plant-pathogen interactions. This study based a pathogenesis-related proteins found from Chinese cabbage root infected by plasmodiophora bacteria. We studied the relationship between salicylic acid signaling pathway and clubroot fungus infection of Chinese cabbage. It provides clues for the molecular mechanisms of Chinese cabbage-Plasmodiophora bacteria interactions. The main results are as follows:1. The primers were designed based on cDNA of differently expressed proteins. Then the expression of inoculated and non-inoculated cDNA was detected by real-time quantitative PCR. The results showed that most of these differently expressed proteins had the same trend in transcription and protein levels, such as the G17, G16, G15 are up-regulated expression after infected by Plasmodiophora bacteria, while F24, G7, G1, G4, G8, G6, G9 are down-regulated expression.2. Six differently expressed proteins verified by real-time quantitative PCR were selected to be analyzed. Their expression was detected in different stages after plasmodiophora bacteria infection, the results showed that G15 and G17 are up-regulated expressed significantly.3. KEGG analysis showed that G15 was involved in plant-pathogen interaction and plant hormone signaling pathway, and the NCBI blastp comparison found G15 has some homology with PR-1 in Arabidopsis, but has the highest homology with CAP of Arabidopsis, suggesting that G15 must be a PR-1 like protein, and was named as BRACAP. The G15 promoter analysis showed that a SA binding site was located the promoter region, which further confirmed that the proteins involved in SA signal transduction pathways.4. Microscopic observation showed salicylic acid can induce Chinese cabbage to prevent plasmodiophora bacteria spores to infect the root hairs, disease survey results show high concentrations of SA will lead to plant death, but 10μmol/L SA can produce the defense response to clubroot.5. The primers of reported SA defense signaling pathway-related genes were designed, Fluorescence quantitative PCR was used to real-time quantitative PCR analyze their response to plasmodiophora bacteria infection in Chinese cabbage, the results showed that the expression of most of these genes are changed, which indicated that SA defense signaling pathway must be induce in Chinese cabbage by plasmodiophora bacteria infection.