Effect of rootstock diversity and grafted varieties on the structure and composition of the grapevine root mycobiome

Background Grapevine is associated with various microorganisms, forming an holobiont. The age of the grapevine and the effect of several declines on the root mycobiota was already studied.AimsGrapevine is an heterografted plant with two different genotypes coexisting, the one from the rootstock and the one from scion. We studied both the effect of rootstock genotype and the grafting of a grape variety on the grapevine root mycobiota. Methods The experiment was carried out in a conservatory vineyard in Burgundy (France) made of two collections: one with rootstocks grown as ungrafted and one with several grape varieties grafted onto the 5C or SO4 rootstocks. Physico-chemical properties were characterized. Soil and roots were sampled to analyse fungal communities with a metabarcoding approach using ITS and LSU as targets and specific of fungi and arbuscular mycorrhizal fungi, respectively. Results Whatever the rootstock, a core mycobiota was associated with roots. In addition, part of root mycobiota is influenced either by the rootstock or by the scion or by the soil. The genetic background could not be fully explored, but it could have a role in the differential recruitment of microorganisms. Conclusion Further studies should focus on both rootstock and scion part, independently and crosswise, in order to better understand the mechanisms involved in specific root microbial interactions within the grapevine holobiont, and to provide a better response to the health and environmental problems affecting grapevines.