Verticillium wilt in potato caused by Verticillium dahliae is a significant problem worldwide, especially in temperate regions. Disease control is complex because Verticillium is a soilborne pathogen with long-lived microsclerotia, and there are no curative treatments. So far, Verticillium wilt is being controlled by environmentally harmful soil fumigants, but these possibilities are limited for Dutch and European agriculture. In the Netherlands—one of the world’s major potato producers and exporters—Verticillium wilt is managed through an integrated crop management approach, including long-term crop rotation and the use of tolerant cultivars. However, because Verticillium species have a wide host range, and microsclerotia can continue to accumulate even in tolerant cultivars, these measures are often insufficient. Stronger and more targeted control strategies are therefore needed to effectively reduce soil inoculum and sustain productivity.
In this project, we aim to harness Verticillium effectors to identify and characterize novel resistance genes from wild potato relatives. We will profile V. dahliae effectors that are expressed during the infection process, from root attraction in the soil up to xylem colonization, and investigate their roles in virulence throughout the fungal life cycle. Then we subject a large collection of chosen V. dahliae effectors for functional effectoromics screens across a set of highly resistant wild Solanum species. This approach will enable the identification of avirulence genes that lead to recognition by previously uncharacterized resistance genes. In parallel, disease assays with diverse V. dahliae isolates will be conducted in selected resistant wild Solanum genotypes and derived mapping populations, with the goal of genetically mapping the resistance loci. Molecular markers developed during this phase will be valuable tools for marker-assisted selection in practical potato breeding. Subsequent fine-mapping and cloning efforts will lead to the molecular characterization of both the resistance genes and their corresponding avirulence effectors. This will provide critical insights into the resistance spectrum and durability of the newly identified resistance sources, supporting long-term strategies for sustainable potato cultivation.

In this project, we aim to identify and characterize novel resistance genes against Verticillium from wild potato relatives. Our approach is based on studying Verticillium effectors (Avr genes), and their functional screening on resistant potato genotypes that help to identify novel resistance (R) genes. By uncovering Avr–R gene pairs, we can accelerate the mapping and cloning of new R genes using functional assays in plants. Furthermore, knowledge of the corresponding Avr genes will provide valuable insight into the underlying resistance mechanisms, the spectrum of recognition, and the expected durability of the resistance. Molecular markers developed during the project will support marker-assisted selection in breeding programs, that can be used by partners in the project. Ultimately, the isolated R genes can be introduced into susceptible cultivars to develop Verticillium-resistant potatoes.

The project will help the development of potato cultivars with a genetic resistance to Verticillium based on a practical application of key technologies belonging to ST2 ‘Biotechnology and breeding’. The research will also contribute to program 2c, Resilient plant production on a healthy soil/substrate.

1. Verticillium effectors (Avr genes) of Verticillium and insight in their biological role
2. Molecular markers for resistance loci and genetic material for resistance breeding by partners
3. Resistance gene(s) against Verticillium with insight into the resistance spectrum and predicted durability
4. Cisgenic potato cultivars carrying the R gene