The fungal endophyte community in grapevines (Vitis vinifera L.)

Abstract

Grapevine trunk diseases (GTDs), caused by a complex of fungi, limit both vineyard productivity and longevity. However, the factors that affect latency of these pathogens in the grapevine trunks is still poorly understood including the interaction between different grapevine fungal endophytes. This study aimed to compare the fungal endophyte community in young and mature Sauvignon blanc vines, both symptomatic and asymptomatic for GTD, using culture-dependent and high-resolution culture-independent approaches. Samples were taken from nine vineyards in the Marlborough region. The samples encompassed 60 mature vines (>10 years old) and 30 young vines (<9 years old), with each age group consisting of equal numbers of apparently healthy and symptomatic vines. Trunk cores were taken from each vine using a sterilised 4-mm drill bit after removing the bark with a knife. Three samples were taken from each vine: a sample from within the canker; at the margin; and beyond the canker in symptomatic vines, with samples taken from similar positions in the asymptomatic vines. For the culture-dependent study, samples were plated onto three different agars and a collection of approximately 2000 endophytic fungi recovered. Taxonomic identification using morphology and DNA sequence information has identified over 40 fungal genera. The results showed that trunk microbiota was dominated (85%) by species of the genera Alternaria, Aureobasidium, Diplodia, Epicoccum, Phaeomoniella, Eutypa, Botrytis and Cladosporium. The abundance of fungal genera was affected by trunk age where Eutypa was dominant in old vineyards and symptomatic vines. The same set of samples were also used for Illumina sequencing of the ITS1 region. These data are currently being analysed and will be compared with the culturable fungal community. This study has produced new baseline information on fungal endophytes in Sauvignon blanc vines and further work will determine the impact of these microbial communities on the latency of GTDs.