Induction of resistance in barley against Erysiphe graminis f.sp. hordei by free cutin monomers
1996
Schweizer, P. | Jeanguenat, A. | Whitacre, D. | Metraux, J.P. | Mosinger, E.
Enzymatic degradation of plant cuticles at sites of fungal attack may release free cutin monomers. The hypothesis that free cutin monomers are signals for the activation of plant defence reactions was tested in the interaction of barley with the fungal pathogen Erysiphe graminis f.sp. hordei. Topical spray application of cutin monomers partially protected leaves of a highly susceptible barley cultivar against E. graminis, the plants being challenge-inoculated 1-3 days after the application. The degree of protection obtained by the C18 family of cutin monomers equaled protection obtained by the biological inducer E. graminis f.sp. tritici. Microscopic inspection of infection sites indicated enhanced resistance in barley epidermal cells to fungal penetration. Although the cutin monomers tested did not induce a number of defence-related barley genes, protection was eliminated by inhibiting host transcription with cordycepin, suggesting the involvement of inducible host reactions in the observed protection. Two-dimensional display of in vitro translation products from barley mRNA revealed the accumulation of one cutin monomer-induced mRNA, the same mRNA also being induced by pathogen attack. The data are compatible with a model that includes cutin monomers as signal molecules for the induction of disease resistance in barley.
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