Identification and expression characterization of a WRKY transcription factor affecting squalene synthesis in Camellia oleifera

Abstract WRKY-like transcriptional regulators are widely involved in physiological processes such as growth and development, metabolic regulation and environmental response. In this study, we obtained six CoWRKY transcription factors by yeast one-hybrid screening library with reference to the Camellia oleifera genome sequence, using squalene synthase gene (CoSQS) as bait. AOS (Antibody Optimization System) analysis showed that CoWRKY15 had the highest interactions with a confidence level of 0.9026. Bioinformatics analysis showed that CoWRKY15 encodes 346 amino acid residues, was a basic hydrophilic protein, did not contain a transmembrane region, contained one WRKY conserved structural domain and one C2H2 zinc finger structural domain. and belonged to class 2 of the WRKY gene family, and had the closest genetic distance of 0.5564 to the homologous protein of Panax quinquefolius PqWRKY1. The results of prokaryotic expression showed that the CoWRK15 protein with a size of 38.3 kD was successfully induced by adding a final concentration of 0.5 mM ITPG for 4 h at 37℃. The results of subcellular localization showed that CoWRKY15 functioned in the nucleus. The results of CoWRKY15 promoter analysis showed that 8 out of 14 cis-elements with annotatable functions were related to the light response, indicating that the expression of CoWRKY15 was strongly affected by light. The correlation analysis of CoWRKY15 expression and squalene content in Camellia oleifera seed kernels treated under different light quality conditions showed a significant positive correlation.