Fungal endophytes of wild and hybrid Vitis leaves and their potential for vineyard biocontrol.

Plants are colonized by diverse assemblages of fungal endophytes that have potential as biocontrol agents for a variety of crops, including grapevine. Although the diversity of symbionts can be very high in wild plants, the fungal endophytes of wild Vitis plants have not yet been investigated. We surveyed the fungal endophytes of 6 wild populations of Vitis riparia, as well as a cold-tolerant, hybrid grapevine in 5 vineyards (1 certified organic), using 454 pyrosequencing. We detected between 43 and 235 operational taxonomic units per sample, with the highest richness and diversity in the wild, the lowest in conventional vineyards, and intermediate levels in the organic vineyard. Wild plants supported a range of taxa not seen in the conventional vineyards, and vineyards were dominated by relatively few taxa. We also isolated fungi from the wild plants and tested them for their ability to inhibit pathogens of grapevine. Several wild isolates (e.g., Ramularia spp.) were strongly inhibitory to grapevine pathogens. We show that wild Vitis supports a distinct and highly diverse community of fungal endophytes and may represent a rich repository of potential vineyard biocontrol agents.