Zebra Chip is an invasive disease of potato which can cause yield losses of up to 90% on infected fields. The disease is caused by the phloem-limited bacteria Candidatus Liberibacter solanacearum (Lso), which is transmitted by a potato psyllid Bactericera cockerelli. Candidatus Phytoplasma solani (Pso) is another phloem-limited bacterium that causes Stolbur Phytoplasma, and is transmitted by leaf hoppers. Both bacterial pathogens can infect a broad host range and cause disease on various Solanaceae (potato, tomato, pepper) and several vegetables (a.o. carrot, celery). So far, the disease control has been limited to the control of the vector, which involves the application of high amounts of neonicotinoids. B. cockerelli is considered an A1 quarantine pest by the European and Mediterranean Plant Protection Organization (EPPO), and as a primary vector for Lso, causes significant economic losses. Pso is already a problem in East / Southern Europe, and carrot-infecting haplotypes of Lso occur in Spain. Considering that these invasive diseases are spreading fast over the world, it is of high importance to start identifying resistance against Lso and Pso. Plant resistance against the Lso / Pso bacteria themselves has not yet been explored. These pathogens are not easy to work with as they cannot be cultivated in vitro yet and the psyllid requires strict quarantine conditions, thus, we propose to exploit an effectoromics approach by which we can circumvent both issues. In a first step, we will study the effector repertoire of Lso, Pso, and related species with bioinformatics as well as microscopy and functional studies to get insight in the role of the effectors in pathogenicity. Then, we will generate a library of selected effectors and screen these on our collection of wild Solanum species for mounting defense responses. After identifying the genotypes that respond to effectors, we will generate segregating populations and map the resistance genes. Subsequent resistance gene enrichment (RenSeq), and/or bulk segregant RNAseq (BSRSeq) with long read sequencing techniques will lead to molecular markers and ultimately to isolating the resistance genes. We will verify our results by testing selected effector-responding wild Solanum plants as well as potato cultivars transformed with the resistance genes under quarantine conditions for resistance to Lso, and Pso. At the end of this project, we will have identified resistance genes against Zebra Chip Disease and Stolbur, with molecular markers ready that can be used to start breeding resistant cultivars to prevent further damage to the potato.

This project aims to identify genetic sources, resistance genes and molecular markerss that can be used to breed for resistance against Zebra Chip Disease and Stolbur Phytoplasma in potato

This project will lead to healthier plants, reduced environmental impact from fungicides and a more sustainable potato production

This project wille contribute to obtaining cultivars wit natural resistance to Zebra Chip and Stolbur.