Identifying and characterizing Verticillium resistance in potato
Soil-borne Verticillium species cause vascular wilt diseases on a wide range of plant species, including economically important crops. Potato early dying disease, or Verticillium wilt, can cause severe losses on potato yield and quality, especially since symptoms often remain confused with senescence and tolerant plants allow accumulation of inoculum in the soil. So far, Verticillium wilt is being controlled by environmentally harmful soil fumigants. In this project, we aim to identify and characterize genetic resistance against Verticillium in wild Solanum accessions. We will exploit a functional effectoromics breeding strategy, combined with modern sequencing technologies. By expressing proteins secreted by the pathogen (effectors), we will detect the corresponding resistance genes in Solanum plants based on specific defence responses in functional assays. With the available Verticillium genome sequence, knowledge on effectors and in house expertise on sequencing strategies such as resistance gene enrichment sequencing and derivatives thereof, the isolation of new resistance genes from these sources is straightforward. In parallel to the effector assays, we will subject wild Solanum plants to diseases trials and optimize a diagnostic assay for Verticillium. This effector-assisted breeding project will lead to the identification of resistant sources, molecular markers and resistance genes against Verticillium in potato. These results will enable the involved companies to breed for novel varieties that are resistant to Verticillium wilt.
The project will contribute to Priority 44: 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’.
In this project, a number of key technologies belonging to MMIP ST2 “Biotechnology and Breeding”, priority 44 are applied, such as: innovative breeding methods (effector-assisted breeding, a functional genomics strategy that targets new resistance genes by high throughput in planta assays); modern phenotyping techniques, e.g. functional screens with effectors and modern disease phenotyping on whole plants using the facilities from the Netherlands plant eco-phenotyping centre (NPEC); genome technologies, e.g. RenSeq (Resistance gene enrichment sequencing), RLP/KSeq (receptor-like protein/kinase enrichment sequencing) and modern methods for (SNP) marker development and genotyping; bioinformatics & big data, e.g. RNAseq and comparative genomics for effector-prediction and resistance gene identification.
The project will also contribute to Priority 4 and help the development of potato cultivars with a natural resistance to Verticillium and a cropping system in which fungicide use is reduced.
Breeding potato cultivars with a natural resistance means that the project will contribute to mission A (circular agriculture), especially MMIP A2 (Gezonde, weerbare bodem, planten en teeltsystemen, bestand tegen zowel abiotische (klimaatbestendig) als biotische stress) for the soil-borne pathogen Verticillium. Our project will lead to healthier plants, reduced environmental impact from fungicides and a more sustainable potato production. With the obtained knowledge and genes, it might be possible also to tackle the Verticillium problems in other crops such as strawberry and tomato. By helping the development of potato cultivars with resistance to Verticillium, the project will also contribute to mission D (valued, healthy and safe food).
Effector-assisted breeding, an innovative breeding method that targets new resistance genes was started for Verticillium in potato. In the first two years of the project, we will generate Verticillium effectors and screen them for responses on our collection of wild Solanum species. These in planta assays with effectors are based on recognition of effectors by immune receptors or resistance genes. In parallel, we will explore the wild Solanum plants by routine disease tests and by using modern phenotyping techniques, e.g. by disease assessment of whole plants using the facilities from the Netherlands plant eco-phenotyping centre (NPEC). From identified resistant genotypes, segregating populations are being generated and during the second and third year, genetic mapping of the resistance is performed by making use of genome technologies. This will lead to genetic markers that can be used for breeding, and for cloning the resistance genes in the fourth year.
A project meeting was held on 23 September 2021, with a presentation of the first results, and a short report was sent to the four participating companies.