Six different nematode genes were identified as potential targets for gene silencing. Selection was based on data mined from Caenorhabditis elegans (a free-living nematode) RNAi database and preliminary hairy root assays performed in our laboratory. Each of six genes are required for either the overall fitness of the nematode or required for the proper development of their offspring. Silencing vectors were created last funding cycle and were distributed to the Co-PIs at the four institutions.

The soybean transformations with the six RNAi vectors were initiated and are still underway. Several independent transformation experiments have been performed at each location and are in various stages of selection and regeneration. Some of the transformation experiments were recently initiated and are currently under selection. Other experiments that were initiated earlier in the year have yielded putative events testing positive for the transgene and have been regenerated into plants. To date we have recovered putative transgenic events from all six vectors and identified at least three PCR positive events from each vector. Although plant regeneration is still occurring for these events, we have recovered plants from four of our vector constructions. These plants, a total of nineteen separate events, are being grown to maturity in greenhouses. Once these plants have matured the seeds will be shipped to Kansas State University for evaluations in SCN bioassays.

In addition to the production of transgenic events we have also collected three different populations of nematodes in Kansas and used PCR to amplify the genes used in this study. Specifically, we have sequenced gene regions selected from our vector constructions. Three of the genes have been sequenced for these three populations and we have observed that these genes have high homology (98-100%) in the regions we have searched. This observation is critical as sequence homology among the different populations provides additional data that the constructs have an equal chance to be effective on all of these nematode populations.