A Characterization of a Cool Climate Organic Vineyard’s Microbiome

The microbiome, an influential factor affecting plant health and growth, is attracting increasing interest with respect to wine grape production. The purpose of this study was to characterize the microbiome (fungi and bacteria) of the soil, cover crop roots and grape (Vitis spp.) roots across rootstock and depth in a cool climate, organic vineyard. The cover crop consisted of a fescue (Festuca sp.) grass, while grape roots were sampled from ‘New York Muscat,’ a cool climate hybrid, across three root types (ungrafted, ‘3309C’ and ‘Riparia Gloire’) at three root depths (0–15, 15–30 and 30–50 cm). The grape root microbiome was more specialized, with fewer observed amplicon sequence variants (ASVs), for both bacteria (16S) and fungi (ITS) than found in the cover crop and the surrounding soil. Grape roots were dominated by bacterial genera Pseudomonas , Niastella and Rhizobium; most prominent fungal genera were Plectosphaerella, Trichosporon and Ilyonectria. While no correlations were found between alpha diversity metrics and soil parameters, Pseudaleuria RA was correlated with Mn, Fe and Na levels. Soil depth explained a small portion of bacterial, but not fungal, variance and taxonomic composition. Rootstock type explained a portion of both bacterial and fungal variance and taxonomic composition, substantiating the role of host plant genetics in the development of the grape root microbiome. This is the first characterization of the grape root microbiome in a cool climate Canadian vineyard.