Arbuscular mycorrhizal fungi as a sustainable approach to improve grapevine fitness in a changing climate

Abstract

Increasing pressures from both biotic and abiotic stresses threaten grapevine health and vineyard productivity worldwide. Arbuscular mycorrhizal fungi (AMF) inoculants have been shown to offer a promising bio-based alternative to mitigate abiotic stress and pathogen attack by enhancing nutrient uptake, water relations, and plant defence mechanisms. The effectiveness of this relationship between organisms is dependent upon compatibility between AMF strains and grapevine rootstocks, especially under challenging environmental conditions.

In controlled greenhouse trials, three widely used rootstocks (Börner, SO4, Vinto) were inoculated with commercial AMF inoculants and subjected to well-watered versus drought treatments. The following key parameters were measured: root colonization rate, chlorophyll content (Dualex index), flavonoid and anthocyanin accumulation.

The findings demonstrate that colonization rates exhibited significant variation among rootstock–AMF combinations, underscoring that effective colonization is contingent on the specific pairing. For instance, Vinto attained 98.8 ± 1.4 % colonization under drought conditions, in contrast to 93.8 ± 3.2 % observed in its non-inoculated control. Under similar conditions, SO4 demonstrated a significant increase in flavonoid content, from 2.64 ± 1.60 to 5.71 ± 1.29 units, indicating an enhancement in antioxidant capacity of more than 100 %.

These findings underscore the importance of selecting compatible AMF–rootstock partnerships to confer resilience against both biotic and abiotic stresses. Identification of the most effective combinations will guide subsequent field validation and mechanistic studies, facilitating the integration of AMF into sustainable viticulture strategies.