LAUSR

To elucidate the role of catalase (CAT) in Heortia vitessoides Moore, which is one of the most destructive defoliating pests in Aquilaria sinensis (Loureiro) Sprenger forests, a CAT gene (HvCAT) was identified in the transcriptome of adult H. vitessoides. Sequence analyses indicated that HvCAT encodes a protein containing 507 amino acids, including a proximal active site sequence (FXRERIPERVVHAKGXGA), heme-ligand sequence (RLFSYNDTX), heme-binding residues (H73, S112, N146, F151, F159, R352, and Y356), and NADPH-binding residues (P149, H192, Y196, G199, R201, N211, H233, K235, I300, W301, P302, H303, Q442, and L445). A phylogenetic analysis indicated that CAT from lepidopteran species could be assigned to one well-supported cluster. Regarding its stage- and tissue-specific expression profiles, HvCAT was expressed at high levels in fifth-instar larvae, fat body of larvae, and abdomen of adults. Furthermore, when fifth-instar larvae were exposed to thermal stress at 35, 37, and 39 °C, hydrogen peroxide and malondialdehyde content significantly increased. HvCAT mRNA was upregulated when the larvae were exposed to temperatures of 31, 33, 35, 37, and 39 °C. The enzymatic activity of HvCAT was significantly elevated following thermal stress (35 and 37 °C). After the knockdown of HvCAT by double-stranded RNA interference, the expression of thioredoxin peroxidase (Tpx) increased, whereas that of copper zinc superoxide dismutase (Cu/ZnSOD) decreased. Additionally, knocking down HvCAT transcripts in fifth-instar larvae resulted in accelerated death following thermal stress at 35 °C. In summary, the results suggest that HvCAT plays a major role in the thermotolerance of H. vitessoides.