Depth structures the community of arbuscular mycorrhizal fungi amplified from grapevine (Vitis vinifera L.) roots

The diversity of arbuscular mycorrhizal fungi (AMF) associating with grapevines has been determined previously, yet little is known of how the community in roots is shaped by depth in the soil or where roots occur in different management zones of the vineyard (vine row versus alley). The influence of depth, management zone, and time of year on the community of AMF in grape roots was examined. I also tested the potential influence of the alley vegetation on AMF in grapevines by comparing the taxa amplified from roots of other plants retrieved from the alley surface soil to those from grapevines growing in the same zone. Depth shaped the AMF community in grapevine roots more than the management zone based on dissimilarity among all grapevine samples. Time of the growing season did not, although AMF taxa richness was greater in grapevine roots collected in late summer (veraison) than it was in late spring (bloom). The number of abundant AMF taxa in grapevine roots from the uppermost soil depth in the vine row was substantially lower in late spring than in late summer, and this was related to high soil nitrate in late spring. The alley vegetation comprised primarily grass, and clover plants harbored a different AMF community in roots than did intermingled grapevine roots. The change in the AMF community in a single perennial host (grape) that occurred with depth in this study resulted from a shift among common taxa as opposed to the appearance of unique taxa in the subsoil.