UC Riverside Undergraduate Research Journal

Lineage-specific gene expansions may allow insects to adapt and diverge functional traits. The Hansen lab’s chromosomal assembly of the sap-sucking potato psyllid (Bactericera cockerelli) previously identified three rapidly evolving genes associated with protease expression. The current study further analyzed whether or not plant diet and insect life stage might impact protease expression. We fed insects differ- ent plant diets of either potato or tomato at two insect life stages (2nd instar and young adult) to test for differences in insect protease gene expression. First, RNA extractions were conducted, followed by quantitative PCR (qPCR). The study used the Δ-Δ Ct method to analyze the relative comparison of gene expression between two genes and the ANOVA test to determine if there is a relationship between the changes in gene expression. Preliminary data revealed a significant difference between the host plant diets potato and tomato for 2nd instar nymphs for two of the three candidate genes. This project begins laying the foundation for iden- tifying the function of species-specific protease genes that are evolving rapidly in the insect, and ultimately these genes may be involved in host plant adaptation.