Gene expression and functional analysis of silk gland-specific UGT gene in moths

The corn earworm (Helicoverpa zea) is a major agricultural pest devouring numerous economically important plants. Recently, a genomic analysis of the corn earworm identified 45 different UGT genes. Uridine diphosphate glycosyltransferase (UGT) is a multigene family of enzymes responsible for catalyzing glycosylation of small hydrophobic molecules. These enzymes participate in the detoxification of xenobiotics and biotransformation of endobiotics, where glucose conjugation increases the water solubility of lipophilic aglycone compounds. Utilizing quantitative and real-time PCR, we discovered a UGT gene, UGT34, being exclusively expressed in the larval silk glands. Further investigation showed UGT34 to be generally expressed at all larval instar levels and largely expressed in the middle and posterior subsegments of the silk glands. Additionally, the soybean looper (Chrysodeixis includens) was analyzed and found to have similar gene expression patterns, implying that UGT34 may play an important role in the silk glands of moths. To determine the function of UGT34, RNA interference (RNAi) was conducted, but revealed to be unsuccessful. Going forward, we plan to utilize the CRISPR-Cas9 gene editing technique to knock out the UGT34 gene. Single guide RNA (sgRNA) has been designed to induce the non-homologous end joining (NHEJ) pathway for the production of random insertions or deletions at the target site. This technique will allow us to better understand UGT34’s role and overcome the obstacles we faced using RNAi. Altogether, the present study implies that UGT34 may play an important role in silk glands, yet its molecular and physiological function needs to be determined by further study.