Abstract

Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) are beneficial microorganisms that improve plant stress tolerance, nutrition, and growth. It has been reported that AMF and PGPR may enhance the production of plant secondary metabolites, including volatile organic compounds (VOCs) that play a key role in the interaction of plants with the environment and are involved in defence mechanisms. The aim of this study was to determine the effects of AMF and PGPR on plant growth and on volatile metabolome in V. vinifera cv. Cabernet Sauvignon and cv. Sangiovese leaf tissue. Two experiments were set up in order to know the effect of AMF and PGPR on grapevine VOCs. Grapevines were inoculated with AMF (Funneliformis mosseae IMA1/Rhizophagus sp. MCO1) or the PGP rhizobacterium Streptomyces sp. SOI7. All microbial inocula promoted plant growth. Additionally, AMF strongly affected total VOC concentration, increasing up to 84% in leaf tissue compared to control plants. Interestingly, AMF modified the levels of specific VOCs synthesised in different anabolic pathways, that have been related to plant defence or water stress. AMF increased elicitors such as (E)–2–hexenal, geraniol, benzaldehyde and methyl salicylate in V. vinifera cv. Cabernet Sauvignon and cv. Sangiovese leaf tissue. In addition, a significant reduction of C13–norisoprenoids was detected in mycorrhizal treatments of both cultivars, indicating conserved responses of grapevine to mycorrhizal colonisation. By contrast, Streptomyces sp. SOI7 increased specific volatile terpenoids but did not affected total VOC content. The knowledge of the effects of AMF and PGPR on grapevine VOCs may contribute to an integrated and sustainable management of vineyards.