Progress toward less susceptible grapevines to vector-borne diseases

Abstract

Grapevine diseases pose a major threat to viticulture worldwide, causing substantial yield losses and jeopardizing the long-term sustainability of vineyard systems. They are caused by a wide range of pathogens with contrasting epidemiologies. Airborne pathogens, such as many fungi, can often be managed through direct chemical control, mainly based on fungicide applications. However, this strategy depends heavily on chemical inputs and is increasingly challenged by environmental, economic, and societal constraints.

In contrast, many of the most destructive grapevine diseases are caused by vector-borne pathogens, including viruses, bacteria, and phytoplasmas, some of which are quarantine organisms, such as Xylella fastidiosa and the Flavescence dorée phytoplasma. In these pathosystems, disease development depends on a complex tripartite interaction between the host plant, the pathogen, and a biological vector, mainly hemipteran insects and nematodes. Unlike airborne pathogens, direct control of the pathogen itself is generally not feasible. Current management strategies therefore focus on removing infected plants to limit inoculum sources and reducing pathogen spread through vector control, most often using insecticides or nematicides. However, chemical control of vectors raises significant concerns related to resistance development, non-target effects, and increasingly stringent regulatory restrictions. As a result, the sustainable management of vector-borne grapevine diseases remains a major challenge.

An alternative and promising strategy is the development of resistant, or at least less susceptible, grapevine varieties. Nevertheless, this approach faces several limitations, including quarantine regulations that restrict experimental work and the inability to culture some agents in vitro. Moreover, breeding for resistance to vector-borne pathogens is particularly complex and time-consuming due to the involvement of multiple biological partners, difficulties in phenotyping, and the long generation time of grapevine. Resistance may target either the pathogen itself—as illustrated by recent advances in resistance to X. fastidiosa—or the vector, as exemplified by the Nemadex rootstock, which confers resistance to the nematode Xiphinema index, the vector of Grapevine fanleaf virus.

This presentation will provide an overview of current research efforts and strategies aimed at developing grapevine varieties resilient to complex, vector-borne disease threats.