engleski

A novel methyltransferase from the intracellular pathogen Plasmodiophora brassicae methylates salicylic acid

The obligate biotrophic pathogen Plasmodiophora brassicae causes clubroot disease in Arabidopsis thaliana which is characterised by large root galls. Salicylic acid (SA) production is a defence response in plants, and its methyl ester is involved in systemic signalling. P. brassicae seems to suppress plant defence reactions, but knowledge of how this is achieved is scarce. Here, we profile the changes in SA metabolism during Arabidopsis clubroot disease and show that P. brassicae possesses a methyltransferase (PbBSMT) that is involved in SA methylation. The accumulation of SA and emission of methylated SA (MeSA) were observed in P. brassicae-infected Arabidopsis 28 days after inoculation. There is evidence that MeSA is transported from infected roots to the upper plant. Analysis of the Atbsmt1 mutant indicated that the Arabidopsis SA methyltransferase was not responsible for alterations in clubroot symptoms. The PbBSMT protein has a predicted signal sequence indicating that it might be secreted into the host cells. The PbBSMT gene is maximally transcribed when SA production is highest. By heterologous expression and enzymatic analyses we confirmed that PbBSMT can methylate SA, benzoic and anthranilic acids. Taken together, our results suggest that PbBSMT participates in metabolising SA in Arabidopsis.

Arabidopsis thaliana; clubroot disease; methyltransferase; salicylic acid; Plasmodiophora brassicae

nije evidentirano