Microbial consortia inoculants differently shape ecophysiological and systemic defence responses of field-grown grapevine cuttings

Despite microbe-based products for grapevine protection and growth improvement are available, only a few of them contain microbes directly isolated from vine tissues. Here, a collection of endophytic bacterial isolates obtained from grapevine woody tissues was used for producing an ad-hoc inoculum. Bacterial isolates were tested in biocontrol assays against some of the main grapevine pathogens and the seven most performing as biological control agents were selected for a consortium development (SynCom). Before putting them in field, a group of cuttings was inoculated with the developed SynCom, whereas a second one was inoculated with a commercial consortium formed by a mixed inoculum of arbuscular mycorrhizal fungi (AMF) and a rhizosphere Bacillus coagulans bacterial strain (B). After the transplanting in field, eco-physiological parameters were monitored, and samples for biochemical and molecular analyses were collected at the end of the experiment. Integration of physiological data with metabolite and transcriptome profiles have been performed. Results showed that the SynCom slowed down photosynthesis, suggesting a reallocation of energy towards defence pathways. Conversely, the AMF+B treatment led to more balanced physiological performances. Metabarcoding analysis revealed that SynCom-treated plants had a significantly lower abundance of wood-decay pathogens than control or AMF+B plants. Collectively, our findings provide information useful for enabling microbial inoculation exploitation with a refined awareness.