Filamentous fungi as biocontrol agents in olive (Olea europaea L.) diseases: mycorrhizal and endophytic fungi

Abstract

Olive (Olea europaea) is a crop of great agronomic, economic and cultural interest for the Mediterranean Basin, although the increase in world demand for olive oil is expanding its cultivation by other countries in the southern hemisphere. The main olive pathogens include bacteria (Pseudomonas savastanoi pv. savastanoi, Xylella fastidiosa), fungi (Colletotrichum spp., Verticillium dahliae, Fusarium spp. Rhizoctonia solani), oomycetes (Phytophthora spp.) and nematodes (Meloidogyne spp.). To combat these pathogens, different biocontrol strategies have been developed with bacteria and yeasts, although its capacity for establishment in the field entails several difficulties. In this sense, filamentous fungi represent an efficient and effective alternative in the control of the different pathogens of the olive tree. The present review compiles all the studies existing so far in the biocontrol of these pathogens through the use of mycorrhizal and endophytic filamentous fungi, making a separate section for the genus Trichoderma due to the special interest that their use has generated. The mechanisms used by these fungi include competition for space and nutrients, parasitism, antibiosis or activation of the plant's defensive responses, among others.