Verticillium Wilt Resistance in Solanaceous Crops: Genetic Resources, Grafting-Mediated Systemic Defense, and Implications for Productivity

Verticillium wilt, caused primarily by Verticillium dahliae and, in some hosts, V. albo-atrum, causes substantial yield losses in solanaceous crops. The disease is characterized by colonization of the vascular system, which can impair water transport and plant growth. Effective resistance therefore requires restricting vascular colonization while preserving vascular function and plant performance. Although considerable progress has been made in identifying resistance genes and defense responses, the molecular and physiological basis of Verticillium wilt resistance varies widely, and remains incompletely understood across solanaceous crops. Here, we summarize current knowledge of Verticillium wilt resistance in tomato, eggplant, potato, and pepper, focusing on vascular defense, immune signaling, lignification, and major resistance genes, loci, and quantitative genetic factors. We also discuss grafting-mediated resistance, highlighting resistant rootstocks and genetic resources, physiological and rhizosphere mechanisms of rootstock-mediated protection, and the potential roles of mobile signals in rootstock–scion communication. Furthermore, we examine the potential role of lignin remodeling as an interface between vascular defense and plant performance, while distinguishing disease-associated growth losses from potential defense-associated costs. We propose an integrative framework for evaluating resistance through pathogen restriction, vascular function, and agronomic performance, emphasizing that the relationships among these processes require further experimental validation. Finally, we outline future research priorities, including the identification and functional validation of resistance genes, quantitative assessment of vascular defense and its potential growth costs, and investigation of the causal contributions of grafting-associated signals and rhizosphere microbiomes. This review provides a framework for understanding Verticillium wilt resistance across solanaceous crops and highlights research priorities for developing durable resistance while maintaining crop productivity and quality.