Can the grapevine microbiome drive the suppression of grapevine trunk disease?

Abstract

Grapevine trunk diseases, caused by several fungal species, are among the most destructive vine diseases in New Zealand and other grape-growing regions of the world. The control of the diseases is problematic and, currently, there is no approved fungicide for their eradication. This situation has informed the need to seek alternative ways, including a sustainable biological control approach, for the management of the diseases. Therefore, the goal of the current study is to identify taxa present in the grapevine microbiome that contribute to plant health. In some New Zealand vineyards, observations have revealed vines that remain healthy within a background of trunk disease. These vines are termed ‘disease escape’ vines, to represent their apparent health under heavy disease pressure. Recent research on grapevine microbiome has shown that endophytes from these ‘disease escape’ plants could contribute to disease suppression. Putative disease escape vines have been identified in vineyards in three New Zealand vineyard regions, Hawke’s Bay, Marlborough and Waipara. The vines were identified based on their location in a diseased area, maturity, lush canopy and absence of trunk disease symptoms such as cankers, stunted shoots and cupped/chloritic leaves. Trunk core samples were taken from these and neighbouring symptomatic vines using a sterilised 4-mm drill bit. The total fungal and bacterial communities of healthy and diseased samples will be identified and compared using both culture-independent DNA metabarcoding and culture-dependent approaches whereby the samples will be plated on different agar to isolate culturable endophytes. Using the results of the metabarcoding analysis, members of the taxa which correlate with significantly reduced abundance of trunk disease pathogens will be retrieved from the culture collection and evaluated in planta. The results of the research will provide an understanding of the roles (if any) the vine’s microbiome plays in the suppression of grapevine trunk disease.