Transcriptome and Expression Analysis of Glycerol Biosynthesis-Related Genes in Glenea cantor Fabricius (Cerambycidae: Lamiinae)

<i>Glenea cantor</i> Fabricius (Cerambycidae: Lamiinae) is an important pest that damages kapok trees in Southeast Asia with a wide adaptability to temperature. Glycerol is a protectant and energy source for insects in low-temperature environments. However, glycerol biosynthesis-related genes at the molecular level are limited in <i>G. cantor</i>. In this study, the supercooling points and freezing points at different stages were measured, and the cold hardiness of male and female pupae significantly differed. Moreover, a full-length transcriptome of <i>G. cantor</i> was established; glycerol kinase (GK) and glycerol-3-phosphate dehydrogenase (GPDH) genes, which are related to glycerol metabolism, were identified, with a special focus on their expression profiles. A total of 24,476 isoforms stemmed from the full-length transcriptome, along with 568 lncRNAs, 56 transcription factor (TF) families, and 1467 alternative splicing (AS) events. The KEGG pathway enrichment analysis revealed that the isoforms associated with AS were enriched primarily in glycerolipid and glycerophospholipid metabolism. In total, three GK genes and one GPDH gene were identified, and GcGK1 and GcGK3 presented differential sex expression during the pupal stage, which may play a role in thermal adaptability. This study provides a valuable transcriptional database of <i>G. cantor</i> and helps to elucidate the function of glycerol in the thermal adaptation mechanism of longhorn beetles.