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

Abstract

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.). In contrast, the application of sequence specific double-stranded RNAs (dsRNAs) to control fungal pathogens and insect pests has only been recently developed. The possibility of combining these approaches to enhance plant resilience, reducing reliance on pesticides, offers new perspectives for a more sustainable agriculture. In this study, we assessed the potential of utilizing dsRNAs to enhance resilience against esca-related wood fungal pathogens in grapevine, considering various rootstock-scion combinations. The results showed that the scion genotype modulates the ability of the rootstock to cope with the inoculated wood fungal pathogens, mainly by altering the efficacy of producing stilbene compounds. Additionally, we found that dsRNAs reduced the growth of two inoculated esca-related fungal pathogens but they did not completely stop their colonization. Furthermore, wood microbiome data showed that the scion genotype (always belonging to Vitis vinifera species) was also able to influence the rootstock-associated microbiota, with a major effect on the fungal community. Lastly, adverse effects on non-target microorganisms are reported, raising questions on the environmental fate of dsRNAs and how dsRNAs can directly or indirectly affect plant-associated microbial communities.

Keywords: Vitis vinifera; Endophyte community composition; RNA interference (RNAi); esca syndrome; grafting; microbiome; rootstock–scion interactions; wood fungal pathogens.