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.
We have successfully transferred a transgene (16D10-RNAi) into the model plant Arabidopsis thaliana and cultivated potato cv. Desiree. This transgene increases plant resistance against the plant-parasitic nematode Meloidogyne chitwoodi, thus directly relating to sub-objective 1.B. of the in-house project, " 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". Preliminary findings show that nematode infection and reproduction are reduced by 60% or more. We have also transferred the 16D10-RNAi gene into potatoes with other genetic backgrounds (cv. Russet Burbank, cv. Umatilla, PA99N82-4) and are currently regenerating whole transgenic plants for further studies and resistance screening assays. At present, we are screening several dozen putative transformants by PCR and Southern hybridization to confirm the transgenic nature of the plants. Transgenic plants are maintained in tissue culture and under greenhouse conditions and will be subjected to nematode infection in the greenhouse.
This research is important because it will aid in developing a new source of resistance against root-knot nematodes and provide an alternative to costly and potentially harmful pesticide applications.