东方蜜蜂幼虫封盖信息素含量及生物合成通路

【目的】在蜜蜂中,甲基棕榈酸酯（MP）、甲基油酸酯（MO）、甲基亚油酸酯（ML）和甲基亚麻酸酯（MLN）是重要的封盖信息素成分,它们触发成年工蜂对幼虫的封盖行为。本研究旨在比较封盖信息素化学成分在不同封盖时期的东方蜜蜂（Apis cernana）工蜂与雄蜂幼虫体内的含量,并分析其在幼虫体内的生物合成通路,进一步探索蜜蜂幼虫与成年工蜂之间的信息素交流机制。【方法】以中华蜜蜂（Apis cernana cernana）为实验材料,分别取未封盖、正在封盖和已封盖的工蜂与雄蜂幼虫,利用GC/MS分析技术,比较4种封盖信息素成分在不同封盖时期的工蜂与雄蜂幼虫体内的含量;同时利用RNA-seq技术对不同封盖时期的工蜂与雄蜂幼虫进行转录组测序,分析其基因表达差异,并根据差异表达基因KEGG富集分析推测封盖信息素的生物合成通路。【结果】在工蜂幼虫中,4种封盖信息素成分在正在封盖和已封盖幼虫体内的含量均显著高于未封盖幼虫,其中MP和MO的含量均随幼虫日龄增长而显著增加,而ML和MLN的含量在正在封盖和已封盖幼虫体内差异不显著;在雄蜂幼虫中,4种信息素成分含量均随日龄增长而增加,且已封盖幼虫的信息素含量显著高于未封盖和正在封盖的幼虫。对工蜂与雄蜂3个封盖时期幼虫的基因表达量进行组间比较分析,分别从3个比较组中获得4 299和3 926个差异表达基因,并且在差异表达基因KEGG注释分析中分别获得152和130个KEGG通路。根据差异表达基因KEGG富集结果,推测出东方蜜蜂工蜂与雄蜂幼虫可能利用乙酰辅酶A合成MP、MO、ML和MLN的生物合成通路以及11个调控候选基因,并发现该生物合成通路与西方蜜蜂相同。【结论】东方蜜蜂工蜂幼虫与雄蜂幼虫在被封蜡盖的关键阶段增加了MP、MO、ML和MLN的释放量,进一步验证了它们是与蜜蜂封盖行为相关的信息素,并且推测这些信息素可能是在相关基因的调控下由乙酰辅酶A从头合成,而东方蜜蜂幼虫与西方蜜蜂幼虫可能利用相同的生物合成通路进行信息素的生物合成。

The Capping Pheromone Contents and Putative Biosynthetic Pathways in Larvae of Honeybees Apis cernana

【Objective】 In honeybees, methyl palmitate (MP), methyl oleate (MO), methyl linoleate (ML) and methyl linolenate (MLN) are important capping pheromone components, which trigger the capping behavior of adult workers. The objective of this study is to compare the contents of these four pheromone components in the larvae of workers and drones of Apis cernana at different capping stages, analyze their biosynthetic pathways, and to further explore the mechanism of pheromone communication between larvae and adult workers. 【Method】Using A. c. cernana as the experimental material, the larvae of workers and drones of prior to be capped, in the process of being capped and had been capped were collected for comparing the contents of these four pheromone components by using GC/MS. Simultaneously, RNA-seq was used for gene expression analysis, and the biosynthetic pathways were speculated based on KEGG enrichment of differential expressed genes. 【Result】In worker larvae, the contents of the four capping pheromone components were significantly higher at the capping and capped stage than those of the prior to be capped larvae, and the contents of MP and MO significantly increased with aging of the larvae, while the contents of ML and MLN were not significantly different between the capping and capped stage. Whereas in drone larvae, the contents of the four pheromone components were higher overall and increased with aging, and the content at capped stage was significantly higher than that at prior to be capped and capping. RNA-seq results showed that there were 4 299 and 3 926 differential expressed genes among the larvae groups of three stages of workers and drones, respectively. In addition, 152 and 130 KEGG pathways were obtained from the KEGG annotation analysis of the differential expressed genes, respectively. Furthermore, the possible de novo biosynthetic pathways were proposed for MP, MO, ML and MLN from acetyl-CoA, regulating under 11 related candidate genes, and these biosynthesis pathways were found to be similar to those of Apis mellifera. 【Conclusion】The release contents of MP, MO, ML and MLN were increased during the critical stage of capping in worker and drone larvae of A. cernana, which further verified that these four pheromones were related to capping behavior of honeybees, and it was speculated that they were possibly de novo biosynthesized from acetyl-CoA under the control of related genes. A. cernana larvae and A. mellifera larvae may use the same biosynthesis pathway for pheromone biosynthesis.