意大利蜜蜂幼虫防御素Defensin-2在吡虫啉胁迫下的表达分析

防御素在昆虫免疫抵抗农药危害中具有重要作用，但蜜蜂防御素Defensin在幼虫抵御吡虫啉毒性中的作用鲜有报道。生物信息学鉴定意大利蜜蜂Apis mellifera ligustica防御素Defensin-2，分析其在吡虫啉暴露下蜜蜂幼虫中的表达模式，探讨其在幼虫抵御吡虫啉中的作用。生物信息学方法分析Defensin-2的氨基酸序列特征、功能域、高级结构、互作靶标、系统进化聚类关系；RT-qPCR分析幼虫口服暴露吡虫啉后Defensin-2基因的表达特征。结果显示，Defensin-2蛋白由104个氨基酸残基组成，相对分子质量为11.9 kDa，等电点PI为8.54，具有信号肽和跨膜结构域。多重序列比对显示Defensin-2属于防御素样超家族。系统进化分析表明，Defensin-2聚类于蜜蜂家族；RT-qPCR分析表明，在半致死浓度吡虫啉暴露下，Defensin-2基因在24 h时显著上调表达后在72 h时下调表达，但在环境浓度吡虫啉暴露后72 h，Defensin-2表达量呈显著上调。Defensin-2可能在意大利蜜蜂幼虫抵御吡虫啉毒性中发挥着重要作用。

Expression analysis of defensin Defensin-2 of Apis mellifera ligustica larvae under imidacloprid stress

Defensin plays an important role in insect immunity against pesticide toxicity, but its role in bee larval resistance to imidacloprid is rarely reported. To bioinformatically identify the defensin Defensin-2 from honey bee Apis mellifera ligustica, analyze its expression pattern and explore its role in larval exposed to imidacloprid. Bioinformatics methods were used to analyze the amino acid sequence characteristics, functional domain, protein structure, interaction target, and phylogenetic clustering relationship of defensin-2. RT-qPCR was used to analyze the expression pattern of defensin-2 gene in larvae after oral exposure to imidacloprid. Defensin-2 protein consists of 104 amino acid residues and was predicted to had a molecular mass of 11.9 kDa and a theoretical PI of 8.54, with a signal peptide and a transmembrane domain. Multiple sequence alignment and phylogenetic analysis showed that defensin-2 clustered in the Hymenoptera honeybee family and could be classified into the defensin-like superfamily. RT-qPCR analysis showed that defensin-2 gene expression was significantly up-regulated at 24 h and then down-regulated expression at 72 h under the semi-lethal concentration of imidacloprid exposure. However, defensin-2 expression was significantly up-regulated at 72 h after ambient concentrations of imidacloprid exposure. Defensin-2 may play an important role in protecting against imidacloprid toxicity in A.mellifera ligustica larvae.