异色瓢虫鞘翅黑化途径及关键基因功能解析

Harmonia axyridis is an important predatory natural enemy in agriculture and forest in China, the elytra of H. axyridis has various phenotypes, the black or yellow were used as base color, mosaic red or black spot. It has been reported that melanization lead to various phenotypes of H. axyridis elytra. In addition, some reports demonstrated that low temperature induce the melanin synthesis and then increase the fitness of H. axyridis. However, the melanization pathways of elytra and relevant genes functions in H. axyridis have not been described. In this project, tyrosine hydrolase in dopa melanin synthesis pathway and the dopa decarboxylase in dopamine melanin synthesis pathway was used to investigated the melanization pathway of H. axyridis: 1) analysis the structure and expression characteristic of tyrosine hydrolase (HaTH) and dopa decarboxylase (HaDDC) genes; 2) Analyze function of HaTH and HaDDC in the growth and development of H. axyridis using RNAi technique; 3) Analyze the relationship of dopa melanin/dopamine melanin and elytra melanization of H. axyridis. The functions of the tyrosine hydroxylase and dopa decarboxylase of H. axyridis were identified and the melanization pathway of elytra was revealed through above studies. The results of the project will provide a scientific basis for the study of the phenotype differentiation of H. axyridis elytra and the mechanism of temperature regulation of melanin synthesis, and also provide theoretical basis about improve the control efficiency in the special environment through regulating the number of black individuals in H. axyridis.

异色瓢虫是我国农林业上重要的捕食性天敌昆虫，其成虫鞘翅表型变化丰富，以黑色或黄色为底色，镶嵌红色或黑色点状色块。黑化可能是引起其鞘翅表型分化的原因。研究报道低温可以诱导异色瓢虫鞘翅黑色素合成进而提高种群适合度。但有关异色瓢虫鞘翅黑化途径及相关基因功能还未报道。本项目以异色瓢虫鞘翅黑化途径为主题，以多巴黑色素合成中酪氨酸羟化酶（TH）和多巴胺黑色素合成中多巴脱羧酶（DDC）为切入点: 1）分析明确HaTH和HaDDC基因结构特征和表达特性; 2）应用RNAi技术分析HaTH和HaDDC在异色瓢虫生长发育过程中的功能；3）应用RNAi技术分析多巴和多巴胺黑色素与异色瓢虫鞘翅黑化的关系。通过上述研究，明确HaTH和HaDDC的基因功能，揭示异色瓢虫鞘翅黑化途径。研究结果将为其鞘翅表型分化及温度调控黑色素合成机制的研究提供科学依据，也为通过调控异色瓢虫种群中黑化个体数量提高其控害效率提供理论基础。

异色瓢虫是我国农林业上重要的捕食性天敌昆虫，其鞘翅色斑类型非常丰富，也是研究昆虫表型多样性的理想材料。黑化是引起其鞘翅表型变异的首要原因。但有关异色瓢虫鞘翅黑色素合成途径及相关基因功能还未见报道。本项以揭示异色瓢虫鞘翅黑色素合成途径为核心；利用分子克隆和基因沉默等技术：1）克隆并鉴定了异色瓢虫酪氨酸羟化酶（HaTH）和多巴脱羧酶（HaDDC）基因的全长序列信息，并分析了序列特征；2）研究明确了HaTH和HaDDC在异色瓢虫整个发育历期均有表达；3）利用RNAi技术研究明确了HaTH和HaDDC均具有基因多效性，HaTH是异色瓢虫生长发育中的必需基因，HaDDC通过调控异色瓢虫卵母细胞到成熟卵粒的发育过程进而调控生殖力；4）利用RNAi技术研究明确了多巴胺黑色素合成途径是异色瓢虫鞘翅黑化的主要途径。该研究成果可为异色瓢虫鞘翅色斑多样性形成机制的解析提供理论基础，同时也为通过调控异色瓢虫种群结构提高其控害效率提供理论基础。