Conjoined partners: efficacy and side-effects of grafting and dsRNAs application on the microbial endophyte population of grapevine plants inoculated with two esca-related fungal pathogens

Grafting has been exploited since 7000 BC to enhance productivity, disease resistance and adaptability of cultivated plants to stressful conditions especially in woody crops such as grapevine (Vitis spp.). On the contrary, the application of sequence specific double-stranded RNAs (dsRNAs) to control fungal pathogens and insect pests has only been recently developed. The possibility to combine these approaches to enhance plant resilience, reducing the reliance on pesticides, offers new perspectives for a more sustainable agriculture. In this study, we assessed the potential of utilizing dsRNAs application to enhance resilience against esca-related wood fungal pathogens in grapevines, considering various rootstock-scion combinations. The results show that scion genotype modulates the rootstock ability to cope with the inoculated wood fungal pathogens, mainly by altering the efficacy to produce stilbene compounds. Additionally, we report the ability of dsRNAs to reduce the growth of the two inoculated esca-related fungal pathogens but not to completely stop their colonization. Furthermore, the microbiome of grape woods data clearly showed that, the scion genotypes (always belonging to Vitis vinifera species) is also able to influence the rootstockassociated microbiota, with a major effect on the fungal community. Lastly, adverse effects on nontarget microorganisms have been reported opening questions on the environmental fate and how dsRNAs can directly or indirectly affect the plant-associated microbial communities.