温度及寄主驱动下桉树枝瘿姬小蜂的表型可塑性及其分子机理

Eucalyptus is one of the most economical efficiency trees in south of China, which is faced with the damage of invasive species Leptocybe invasa. This pest spread rapidly and pose a enormous threats to the development Eucalyptus industry in China. This project focus on the scientific problem with phenotypic plasticity and adaptive evolution of Leptocybe invasa. Based on comparison study of the phenotypic plasticity of Leptocybe invasa in different geographic populations, determining the phenotypic plasticity and adaptive evolution of Leptocybe invasa in response to long-term stress of temperature and host plants by methods of common-garden and reciprocal-transplant experiments. By determining the pest’s stress-resistant substances, protective enzyme systems, detoxifying enzymes and expression of heat shock proteins under temperature and host plants stress, exploring the formation and evolution of Leptocybe invasa’s phenotypic plasticity and its molecular mechanism. This project not only contributes to some practical problems as to whether phenotypic plasticity of the pest is of maternal effects and adaptive evolution, why the pest spreads very quickly, whether the pest will continue to spread et al, clarifies the invasion mechanism of the pest and enriches theory of invasion biology, but also is benefit to predicting accurately the dynamic of invasion and spread of the pest and taking effective measures to control the invasion and spread of it, especially provides reference against new biological invasion under the background of global warming.

桉树是我国南方效益最高的树种之一，目前正遭受着入侵生物桉树枝瘿姬小蜂的危害，该虫的迅速蔓延，对我国桉树构成了重大威胁。本项目围绕桉树枝瘿姬小蜂表型可塑性和适应性进化这一科学问题，在对我国桉树枝瘿姬小蜂不同地理种群表型可塑性进行比较分析基础上，采用同质园交互移植实验的方法对该虫进行多世代连续模拟环境胁迫与驯化处理，研究该虫表型可塑性变化程度和趋势；通过检测温度和寄主胁迫下该虫体内抗逆物质、保护酶和解毒酶活性以及热激蛋白表达变化，探讨该虫表型可塑性形成及其进化的分子机制。该研究不但有助于回答该虫表型可塑是否存在母代效应和适应性进化、该虫为何能迅速入侵扩散以及是否还会继续扩散等实际问题，阐明该虫入侵扩散机理，丰富入侵生物学理论；而且有助于对该虫入侵扩散动态进行准确的测报，并采取有效措施遏制其进一步蔓延；更为全球气候变暖背景下如何抵御新的生物入侵提供借鉴。

桉树是我国南方效益最高的树种之一，目前正遭受着入侵生物桉树枝瘿姬小蜂的危害，该虫的迅速蔓延，对我国桉树构成了重大威胁。本项目在对我国桉树枝瘿姬小蜂不同地理种群表型可塑性进行比较分析基础上，研究温度和寄主对该虫表型可塑性的影响；通过对不同地理种群桉树枝瘿姬小蜂转录组学分析探讨该虫表型可塑性形成及其进化的分子机制；为阐明该虫入侵扩散机制奠定基础。主要结果如下：.（1）不同地理种群的桉树枝瘿姬小蜂表型呈现出明显的可塑性变化。1)不同地理种群的桉树枝瘿姬小蜂均表现出明显偏雌性，其中南宁种群的雄虫比例最高。2)不同地理种群桉树枝瘿姬小蜂形态参数差异显著，高纬度地区种群个体显著小于低纬度地区种群的个体，且与纬度变化呈现明显相关。3)不同地理种群桉树枝瘿姬小蜂体内细菌种类及相对丰度均有较大差异。.（2）温度驱动桉树枝瘿姬小蜂表型发生明显变化。1)在一定温度范围内，桉树枝瘿姬小蜂的形态参数随温度升高而下降。2)将不同地理种群桉树枝瘿姬小蜂接种于广西大学苗木培育基地，其第5代的形态指标显著增大。3)不同温度下桉树枝瘿姬小蜂呼吸作用强度及保护酶活性发生明显变化。4)不同季节对桉树枝瘿姬小蜂体内可培养菌群组成及其多样性有明显影响，夏季种群体内细菌多样性更高。.（3）寄主驱动桉树枝瘿姬小蜂表型发生明显变化。1)不同寄主间桉树枝瘿姬小蜂的表型参数差异显著，以巨园桉DH201-2为寄主的桉树枝瘿姬小蜂个体的大小显著大于以窿缘桉为寄主的个体。2)不同寄主植物对桉树枝瘿姬小蜂体内解毒酶活性不同，以巨园桉DH201-2为寄主的桉树枝瘿姬小蜂4种解毒酶活性均高于以窿缘桉为寄主的桉树枝瘿姬小蜂解毒酶活性。3)不同寄主桉树枝瘿姬小蜂体内细菌群落组成和种类多样性存在差异。.（4）对福建和四川种群的桉树枝瘿姬小蜂进行了转录组测序，发现差异基因465个。基于转录组数据发现了大量与抗应激相关的候选基因和基因家族。.（5）发现了一种新的桉树枝瘿姬小蜂寄生性天敌：四川大痣小蜂(Megastigmus sichuanensis Doğanlar & Zheng sp. n.)。. 结论：温度和寄主对桉树枝瘿姬小蜂的形态、生理代谢、体内微生物及抗性基因的表达等均产生明显影响，桉树枝瘿姬小蜂具有明显的表型可塑性。