Grafting as a Sustainable Approach to Mitigate Potato Virus Y (C-To Strain) Infection in Local Tomato Ecotypes from the Campania Region

Abstract

Tomato (Solanum lycopersicum L.) is one of the most important solanaceous crops due to its economic and nutritional relevance. It hosts a wide range of plant pathogens, including a recombinant strain of potato virus Y (PVYC-to), which is considered one of the major threats in tomato cultivation. PVYC-to, a single-stranded RNA plant virus (family Potyviridae), mainly causes symptoms of mosaic, chlorosis, and vein necrosis in the leaves of horticultural crops, resulting in significant production losses. The ongoing evolution of viral strains, combined with the absence of natural resistance genes in commercial germplasm, requires the exploration of alternative management strategies, such as grafting, and the identification of resistant genetic resources within local biodiversity. This study aims to evaluate the response of five local tomato ecotypes (LTEs) from the Campania region—Corbarino, Giallo determinato da serbo, Pizzutello, San Marzano, and Vesuviano—to PVYC-to infection. The goal is to identify a naturally tolerant ecotype for use as a rootstock for commercial tomato varieties and expand the pool of resilient genetic resources against viral diseases. Visual symptom evaluation at 14 and 28 days post-inoculation (dpi), quantification of virus accumulation by qDot-blot, and thermal imaging analysis showed that all tested tomato ecotypes were susceptible to PVYC-to infection, although at different levels among the tested ecotypes. More specifically, Corbarino showed no significant changes in canopy temperature values, fewer symptoms, and reduced virus accumulation upon PVYC-to infection, compared to the other LTEs, and was therefore selected as a rootstock in subsequent experiments. The reduction in both symptom severity and viral RNA accumulation observed in grafted plants, combined with the mitigation of thermal stress in grafted scions, confirmed the efficacy of grafting as a viable management strategy and eco-friendly cornerstone for safeguarding regional agro-biodiversity against escalating viral pressures.