Functional complexity of Parthenium beetle, Zygogramma bicolorata (Pallister) under thermal-stress conditions: Insights from Gene Ontology

Abstract

We analyzed protein expression profiles in Parthenium beetles exposed to cold (15 °C), optimal (25 °C), and heat (35 °C) temperatures. The beetle is an effective biocontrol agent against the invasive Parthenium weed. We identified 620 proteins under cold stress, 334 proteins at the optimal temperature, and 603 proteins under heat stress, with 181 proteins common to all three temperature conditions. Compared to the 106 proteins expressed at the optimal temperature, 196 proteins were overexpressed under cold stress, while 180 proteins were overexpressed under heat stress. Under cold stress, significant Gene Ontology (GO) terms for molecular functions included pyridoxal phosphate binding, pyrophosphatase activity, and RNA helicase activity. Enriched cellular component terms were trans-Golgi network transport vesicle, endosome, and small ribosomal subunit. Biological processes emphasized small molecule biosynthesis, protein refolding, and carbohydrate metabolism. Under heat stress, significant GO terms for molecular functions involved proton transmembrane transporter activity, poly-A binding, and oxidoreductase activity. Cellular component terms included cytosol, coated vesicle, and nucleosome. Biological processes highlighted regulation of cellular stress response, primary active transmembrane transport, and heterochromatin formation. These findings reveal distinct protein sets and associated functions under thermal stress, providing insights into the beetle’s molecular mechanisms of thermal adaptation. The enriched GO terms indicate activation of different molecular pathways in response to cold and heat stress, involving various metabolic, transport, and stress response processes.