Induction of Defense-Related Responses and Suppression of Grey Mold in Grapevines Treated with Defense Response Signaling Mulecules

Abstract

The induction of defense responses in grapevines to fungal pathogens was studied on leaves of the cultivars 'Campbell Early' and 'Kyoho' which were treated with ethephon, hydrogen peroxide (H ₂O ₂), methyl jasmonate (MeJA), and salicylic acid (SA). Applying the chemicals resulted in an increase in expression of several defense-related genes and accumulation of stilbene compounds and gamma-aminobutyric acid (GABA). The expression of plant defense-related genes such as catalase (Cat),chalcone synthesis (CHS),chitinase-like protein (CLP),flavonol synthase gene (FLS),glutathione-S-transferase (GST),stilbene synthase (STSY),and thaumatin-like protein (TLP),as well as signal transduction-related genes including lipoxygenase (LOX),was variously induced by the treatments in both cultivars. Additionally, cell wall modification-related genes such as polygalacturonase-inhibiting protein (PGIP)and proline rich protein (PRP2)were slightly upregulated by treatment with signaling molecules in both 'Campbell Early' and 'Kyoho'. Stilbenoid glucosides, including trans-and cis-piceid, accumulated to high concentrations in grapevines that were subjected to chemical treatment. The concentration of GABA in leaves increased following pretreatment with all of the signaling molecules tested. Additionally, pretreatment with signaling molecules resulted in reduced lesion size after inoculation of leaves with Botrytis cinerea. These results indicate that plant signaling molecules can be used to elicit a resistance responses against infection by pathogens in grapevine and might offer a tool to manage certain diseases.