【摘要】 【目的】研究寄生性天敌昆虫热激蛋白HSPs的功能,为探讨寄生性天敌昆虫的小分子热激蛋白对农药与紫外胁迫下的抗逆性作用提供基础。【方法】克隆白蛾周氏啮小蜂的一个小热激蛋白基因Ccshsp12.2,对其从系统发育、核苷酸替换速率和密码子使用偏好性等方面进行分析,并利用实时荧光定量PCR(RT-qPCR)技术研究其经紫外照射及用阿维菌素、苏云金杆菌、灭幼脲和高效氯氰菊酯4种农药处理后,Ccshsp12.2的表达量变化。【结果】获得了含有完整编码区的Ccshsp12.2基因序列,编码206个氨基酸,分子量为23.1 kDa;进化分析结果表明白蛾周氏啮小蜂等寄生性类群与麦茎蜂等自由生活类群聚成2个分支。选取的9条基因平均Ka/Ks(即dN/dS)值为0.906 556,主要接受负选择压力。寄生性昆虫的平均密码子选择偏好性指数为0.344,自由生活昆虫的平均密码子选择偏好性指数为0.353。RT-qPCR试验结果显示,与对照相比,经农药和紫外线的处理后,白蛾周氏啮小蜂Ccshsp12.2表达量均有所上调,达3.36～6.17倍。【结论】通过分子进化分析,发现不同生活方式的昆虫其热激蛋白所受的进化压力有显著差别;紫外照射及阿维菌素等4种农药均能显著诱导Ccshsp12.2基因表达上调。本研究结果将为白蛾周氏啮小蜂HSPs的抗逆性研究提供依据。更多还原

【Abstract】 【Objective】 This study aimed to study the role of small heat shock protein(sHSP) in parasitoids and explore the resistance of the heat shock proteins from parasitic natural enemies to pesticides and ultraviolet stress. 【Method】 The small heat shock protein gene of Chouioia cunea(Ccshsp12.2) was cloned and was used for constructing a phylogenetic tree, calculating amino acid substitution rate and codon usage bias. The RT-qPCR technique was used to quantify the relative expression of Ccshsp12.2 under ultraviolet and treatments with four kinds of pesticides(Abamectin, Bacillus thuringiensis, chlorbenzuron and Beta-cypermethrin).【Result】The Ccshsp12.2 gene with complete ORF was obtained, encoding 206 amino acid with a molecular weight of 23.1 kDa. The phylogenetic trees showed two lineages, Ccshsp12.2 was clustered with other parasitoids in to one group, while Cephus cinctus was clustered with other independent Hymenoptera insects into the other. The average value of Ka/Ks(dN/dS) in 9 selected mRNA sequences is 0.674 067, which means that those genes appear to be primarily negatively selected. In addition, the average codon usage bias of parasite insect is 0.344, while it is 0.353 among independent insect. The result of RT-qPCR showed that Ccshsp12.2 was up-regulated by the effect of insecticides and ultraviolet independently. The relative expression of Ccshsp12.2 was 3.36-6.17 times higher than the control under the treatment of insecticides and ultraviolet A radiation. 【Conclusion】 The phylogenic result and molecular evolution analysis showed that Hymenoptera insects with different living style might suffer from different evolution stress. Ccshsp12.2 was induced in response to ultraviolet and 4 kinds of pesticides. The findings in this study would provide some clues for the investigation about the response of C. cunea to a biotic stresses and insight into the use of this parasitoid in biological control strategies.更多还原