1a. Objectives (from AD-416):
Identify nematode genes important in the parasitism process. Produce potatoes that interfere with parisitism process, reducing damage and lowering the need to use fumigants. Use knowledge gained to understand the nematode-plant interaction that leads to success for the nematode and how to interfere with that.
1b. Approach (from AD-416):
Gene products that are expressed and secreted by the nematode will be traced back to their genes. Interfering RNA's directed at thwarting these genes will be inserted in the plant in expression cassettes. When a nematode invades and starts to change the cellular environment of the root to suit its developmental and reproductive needs, one or more of the genes behind this process will be partially or completely nullified leading to nematode developmental and reproductive failure.
3. Progress Report:
Root-knot nematodes are a significant threat to potato production. Current control measures are extremely limited and largely rely on costly pesticide applications. In order to develop new sustainable control strategies, the goal of this project is to disrupt the molecular interactions between the nematode and its host plant. To this end, we deactivated a root-knot nematode-specific gene that is essential for parasitic success by plant-mediated RNA interference (RNAi). In 2013, we generated transgenic RNAi potato lines from different cultivars (cv. Desiree, Russet Burbank and an advanced breeding line). Using infection assays under growth chamber and greenhouse conditions we found that these transgenic RNAi lines show a dramatic increase in root-knot nematode resistance in roots and tubers. Both symptom formation (galls) and nematode reproduction as measured by number of eggs produced were decreased by 50% or more. Importantly, the potato lines tested were resistant against a range of root-knot nematode races that are able to overcome a native resistance gene found in potato. Ongoing experiments are testing how stable this resistance is under different temperature regimes and during tuber storage. Taken together, this project is a significant advance for root-knot nematode management strategies in potato and could dramatically reduce production costs by reducing the need for fumigant and non-fumigant pesticides, thereby increasing farm productivity. This project falls within project Potato Germplasm Enhancement through Trait Discovery, Genetic Evaluation and Incorporation (5354-21220-010-00D) and addresses Sub-objective 1.B.: “Develop germplasm with resistance to pests and diseases, establishing effective and efficient screening protocols, determining range of expression, inheritance, heritability, and discover molecular markers, while mapping genetic factors where possible and useful.”