Grapevines (Vitis vinifera L.) contain diverse communities of culturable fungi that differ between organic and standard management systems in New Zealand

Abstract

Grapevines contain a diverse community of microorganisms that includes pathogens and beneficial fungi. Some pathogenic fungi are causal agents of grapevine trunk disease (GTD) and are considered latent pathogens. For GTD, understanding of the factors affecting latency is lacking. The aim of this study was to describe the fungal endophyte community in vines of Sauvignon blanc that were symptomatic and asymptomatic for GTD and grown under standard and organic management practices. Samples were taken from 90 grapevines in nine vineyards in the Marlborough region, the largest winegrowing area in New Zealand. The samples encompassed 30 young vines (<9 years), 60 mature vines (>10 years) of which equal numbers were symptomatic (visual canker) and asymptomatic (no visual canker). Samples were collected from the trunk using a sterilized 4-mm drill bit after removing the bark by a knife. Three samples were taken from each vine, with samples from within the canker, at the margin and beyond the canker in symptomatic vines. Samples were plated onto a range of agars and a collection of approximately 2000 endophytic fungi recovered. Taxonomic identification using morphology and DNA sequence information has identified at least 42 genera. Trunk microbiota was dominated (85.25%) by species of the genera Alternaria, Aureobasidium, Diplodia, Epicoccum, Phaeomoniella, Eutypa, Botrytis, Cladosporium and Diaporthe. Differences in the taxa recovered into culture were observed between vines of different ages, symptomology and those under different management systems. For example, seven and six taxa were found exclusively in vines under conventional and organic management, respectively. This live collection will be complemented by further work using metabarcoding to characterise the complete fungal community and their relative abundance. This study has produced new baseline information on fungal endophytes in Sauvignon blanc and further work will determine the impact of these microbial communities on the latency of GTDs.