Cyst nematodes are parasitic roundworms of plant roots that cause severe yield and quality loss in many agricultural systems. In the US, the soybean cyst nematode is the most serious pathogen problem in soybean production. Only very limited control options for these plant pathogens exist and further research into their biology is needed to uncover novel control targets. In order for cyst nematodes to be successful, they need to be able to completely change their host plant at the cellular and physiological level. At the heart of these changes are massive alterations of plant gene expression patterns under the control of the nematode, i.e., these plant parasites are able to reprogram plant cells for their own benefit. It is unknown how cyst nematodes are able to do this, but the investigators will use the model plant Arabidopsis and the beet cyst nematode to explore a new mechanism that they have shown to be involved in cyst nematode parasitism, namely the effects of plant microRNAs (miRNAs), which are powerful regulators of gene expression. The investigators will characterize four miRNAs that they have shown to be active at the site of nematode infection and they will identify additional regulatory RNAs. As a result, the scientific community will gain understanding of cyst nematode parasitism and, more importantly, this project will identify potential avenues to interfere with cyst nematode parasitism with the goal to engineer crop plants that are resistant, which would eliminate billions of dollars in yield loss world-wide. Broader impacts are the training of young scientists as well as an involvement of high school teachers who will produce a training video module on cyst nematodes, which will be an eye-opening teaching tool for students of all backgrounds.