To future-proof tomato production against increased disease pressure, this project will identify, characterize, and deploy novel, more durable genetic resistance genes against the fungal pathogen Fulvia fulva, which causes leaf mould disease of tomato.
Resistance to F. fulva in tomato has long relied on the use of Cf genes, which encode extracellular immune receptors that recognize secreted fungal effector proteins and mediate resistance through the activation of a so-called hypersensitive response (HR). A number of Cf resistance genes, originating from wild tomato relatives, has been cloned and is currently being used in resistance breeding. Unfortunately, all the current Cf genes are overcome by specific F. fulva strains harbouring mutations or deletions in the corresponding effector genes. Therefore, there is an urgent need for novel Cf genes that provide durable, broad-spectrum resistance against various races of the fungus. We have recently detected several novel Cf-Ecp genes from wild tomato relatives, which match more conserved F. fulva extracellular protein (Ecp) effector genes. In this project, we aim to clone these tomato Cf-Ecp genes and to predict their durability by editing the corresponding Ecp genes of F. fulva. Furthermore, we will study molecular interactions of Ecps and Cf-Ecps, by identifying their allelic variation and distribution, protein structure (predicted through AlphaFold) and protein-protein interactions, with the objective to develop a prediction model for facilitating the identification and exploration of novel Cf-Ecps in breeding for durable resistance to F. fulva.
The project combines effector biology, genomics, and AI-driven protein structure prediction to understand how fungal effector proteins function and how matching immune receptor genes can be used in breeding to achieve durable resistance. The project will deliver validated Cf-Ecp genes, advanced breeding materials, molecular markers and predictive tools for resistance breeding.

The objective of this project is to achieve durable resistance of tomato against infection by Fulvia fulva.

This project aligns strongly with the KIA Landbouw, Water en Voedsel (LWV) priority 2C: “Climate change & resilient cultivation”, addressing the urgent need for resilient crop production systems in the face of climate change. Specifically, our proposal contributes to plant resilience by developing durable genetic resistance to leaf mould disease of tomato caused by F. fulva, which is a major threat under increasingly humid and unstable growing conditions.

We have planned research activities that are structured into three Work Packages (WPs) to achieve the following expected results:
• Identification and validation of at least seven novel Cf-Ecp resistance genes from wild tomato species, using disease trials, genetic mapping, candidate resistance gene validation, and introgression of resistance into elite tomato backgrounds (WP1).
• Prediction and validation of the role in virulence of F. fulva Ecps matching Cf-Ecp resistance genes, by assessing Ecp contribution to fungal virulence through gene editing in F. fulva; and by protein structure prediction and validation of protein-protein interactions (WP2).
• Exploration of Ecp and Cf-Ecp diversity and developing a framework for predictive resistance breeding, by combining the findings of WP1 and WP2 and extending these with an Ecp/Cf-Ecp allelic variation study to accelerate the discovery and deployment of durable resistance genes (WP3).