Sulfated macroalgal polysaccharides lambda-carrageenan and iota-carrageenan differentially alter Arabidopsis thaliana resistance to Sclerotinia sclerotiorum

摘要

We examined the effect of macroalgal polysaccharides iota- and lambda-carrageenan, which differ in sulfation, on Arabidopsis resistance to the necrotropic fungal pathogen Sclerotinia scleortiorum. Pretreatment of Arabidopsis with highly sulfated lambda-carrageenan induced resistance to S. sclerotiorum resulting in smaller leaf lesions; by contrast, the less sulfated iota-carrageenan enhanced susceptibility. lambda-carrageenan induced resistance correlated with increased expression of jasmonic acid related genes AOS, PDF1.2 and PR3. Further, lambda-carrageenan increased the oxalase oxidase activity in planta. The l-carrageenan induced resistance in the salicylic acid deficient mutant ics1, but did not rescue the susceptibility of jar1 plants suggesting that lambda-carrageenan induced resistance is independent of salicylic acid. The difference in the bioactivity of carrageenans is due, at least partly, to differences in the degree of sulfation