Resistance Induction in Plants by a Brassinosteroid-Containing Extract of Lychnis viscaria L.

Abstract

Abstract Resistance inducing effects of an extract of Lychnis viscaria L. seeds, containing different brassinosteroids (BR), were investigated. Application of aqueous solutions in concentrations from 0.5 to 10 mg/l (dry wt. of extract) resulted in an enhanced resistance of tobacco, cucumber and tomato to viral and fungal pathogens of up to 36% compared with water-treated control plants. No direct anti-fungal effects in mycelium growth assays with Phytophthora infestans could be observed. After treatment and inoculation with powdery mildew a stimulation of different PR-proteins (ca. + 20% for peroxidase, + 30% for chitinase and up to + 68% for β-1,3-glucanase) in cucumber was found. A chitinase in gel-electrophoresisassay showed a stronger induction of a distinct isoform under the same conditions. Time course of peroxidase induction and changes of apoplastic protein patterns revealed by SDS-PAGE indicated an earlier triggering of defence responses after plant-extract treatment and pathogen attack, probably being responsible for the increased resistance. Involvement of the brassinosteroids in the plant extract is discussed to elicit or mediate the activation of defence-mechanisms.