Research Molecular Biologist USDA-ARS/Invasive Insect Biocontrol and Behavior Lab
Enhancing the plants tolerance to chewing insects is an important goal to feeding an ever-increasing population. With the aim of breeding more insect resilient plants, researchers need to understand how expression of defense genes can be weaponized without loss of yield. While there has been an impressive increase in our understanding of how plants respond to infestation and the genes involved, there is clearly more work needed to define additional players in this response. Our lab has been studying C1-2i C2H2 zinc finger proteins (ZFP) in both potato and Arabidopsis. We have identified StZFP2 in potato, which when over-expressed results in lower larval weight of Manduca sexta in no choose feeding assays. To utilize T-DNA insertion lines in Arabidopsis from the Salk institute, we focused on Zat18 a StZFP2 homolog in Arabidopsis. This gene has two T-DNA insertion lines that result in either a knockout or a knockdown level of Zat18. Using qRT-PCR and RNA-Seq the genes responsive to infestation by Trichoplusia ni were identified in Col-0 and the two insertion lines. The knockout and knockdown lines have unique gene responses to each other and to the wildtype line Col-0. The levels of Zat18 are critical to the expression of downstream defense genes. While JA pathway genes were not altered by loss of Zat18, the knockdown line was significantly repressed in JA-Eth pathway genes PDF1.2 and PR4 compared with Col-0 and the Zat18 knockout line. The SA marker gene PR1 decreased upon infestation by 4h whereas Col-0 and knockout line did not change significantly. Several ABA pathway genes were repressed only in the knockdown line and not Col-0 or the knockout line. Suggesting that small but not a complete loss of Zat18 alters the infestation response.