关键词: 松毛虫赤眼蜂, 脂肪酸合酶, 滞育, 甘油三酯, RNA干扰

Abstract: 【Aim】 This study aims to clone the fatty acid synthase (Fas) gene of Trichogramma dendrolimi (TdFas) and analyze its regulatory role in diapause, so as to provide a new basis for diapause research of T. dendrolimi. 【Methods】 Based on the T. dendrolimi transcriptomic data, the full-length cDNA sequence of TdFas was cloned and analyzed by bioinformatics methods. RT-qPCR was used to detect its expression level in prepupae, pupae and adults of diapause and non-diapause individuals, and in prepupae during diapause induction and maintenance period and diapause termination period. The expression of TdFas was interfered by RNAi through soaking T. dendrolimi larvae in dsTdFas solution at the concentrations of 1 000, 2 000 and 3 000 ng/μL to explore its effects on the diapause rate and relative triglyceride content of T. dendrolimi. 【Results】 The full-length cDNA sequence of TdFas (GenBank accession number: OP146440) of T. dendrolimi was cloned and is 8 601 bp in length. The open reading frame of TdFas is 7 278 bp in length, encoding a putative protein of 2 426 amino acids with a typical β-ketoyl reductase domain of fatty acid synthase. The phylogenetic analysis results showed that Td-qPCR results showed that the expression levels of TdFas in diapause prepupae and diapause adults were significantly higher than those in non-diapause individuals, while that in diapause pupae was significantly lower than that in non-diapause individuals. The expression level of TdFas in diapause prepupae increased first and then decreased with time during diapause induction and maintenance period and diapause termination period, and was the highest on the 40th day of diapause induction and maintenance, and the 40th day of diapause termination, respectively. RNAi results showed that 3 000 ng/μL dsTdFas was optimal for silencing TdFas, and in the treatment with this concentration of dsTdFas, the diapause rate of T. dendrolimi (66.04%) was significantly lower than those in the blank control group (96.67%) and dsGfp negative control group (93.88%), and the relative triglyceride content in prepupae was also significantly reduced as compared to those in the two control groups. 【Conclusion】 TdFas of T. dendrolimi has been identified for the first time in this study, and may play an important role in diapause regulation of T. dendrolimi. This study provides a theoretical basis for further study of the mechanism of diapause regulation of T. dendrolimi.

Key words: Trichogramma dendrolimi, fatty acid synthase, diapause, triglyceride, RNA interference