Plant defence via bio-stimulant or antimicrobial peptides application

The management of fungal and bacterial plant diseases mostly relies on chemical control and specifically on the application of copper-based products and/or synthetic fungicides that can determine negative effects on the environment and on the health of growers and consumers. Therefore, searching for new sustainable alternatives to chemical control is crucial. A promising low-impact method for controlling plant diseases is the activation of plant defence mechanisms by treating with natural elicitors or antimicrobial compounds. For example, yeasts contain molecules perceived by plant cell receptors as elicitors and thus able to activate the plant immune response. In this research we evaluated and compared the efficacy of different extracts from the yeast Saccharomyces cerevisiae for their capacity to induce grapevine tolerance to the fungal pathogen Botrytis cinerea, the causal agent of the grey mould disease. Experiments included the combined application of drought stress and B. cinerea infection, and the expression analysis of molecular markers related to water stress and pathogenesis.Trichogin GA IV is a non-ribosomal antimicrobial short peptide naturally produced by the fungus Trichoderma longibrachiatum. Its antimicrobial activity resides in the ability to insert into phospholipidic membranes and form water-filled pores, thus perturbing membrane integrity and permeability. With the aim of developing new sustainable biopesticides, we designed modified trichogin analogs, containing one to three Gly-to-Lys substitutions, to increase water-solubility and antimicrobial activity against plant pathogens. By in vitro and in vivo bioassays, we identified at least two peptide analogs of trichogin effective in reducing Fusarium Head Blight and powdery mildew of wheat and tomato bacterial speck disease under controlled conditions.