Endophytic Beauveria bassiana activates expression of defence genes in grapevine and prevents infections by grapevine downy mildew Plasmopara viticola

Abstract

Fungal entomopathogens like Beauveria bassiana (Ascomycota: Hypocreales) are known as antagonists of insects with multiple functional and ecological roles, and have attracted increased attention as biocontrol agents in integrated pest management programmes. For some crop plants, it has been proven that endophytic B. bassiana, besides its entomopathogenic habit, can provide protection against plant pathogens or limit their damaging effects. However, for grapevine, limited knowledge is available on the influence of endophytic B. bassiana on fungal pathogens and about the mechanisms underlying putative protection effects. This study assessed the protective potential of endophytic B. bassiana against grapevine downy mildew Plasmopara viticola in greenhouse experiments. Three and seven days after a B. bassiana treatment, potted grapevine plants were inoculated with P. viticola and the evolving disease severity was assessed. Disease severity was significantly reduced in B. bassiana‐treated plants compared to control plants, depending on the age of leaves. Furthermore, a microarray and an RT‐qPCR analysis were performed to work out fundamental aspects of genes involved in the interaction between grapevine and B. bassiana. The results indicate an up‐regulation of diverse defence‐related genes in grapevine as a response to endophytic establishment of B. bassiana. Thus, endophytic establishment of an entomopathogenic fungus such as B. bassiana in grapevine plants would represent an alternative and sustainable plant protection strategy, with the potential for reducing pesticide applications in viticulture.