西花蓟马适应寄主植物防御反应的生化及分子机制

Plants and herbivores have formed mutual adaptation mechanisms in the process of the evolution. Plants defense against herbivores through various ways, while herbivores are also adapted to plant defense responses through a variety of strategies. The biochemical and molecular mechanisms of Frankliniella occidentalis adaptation to host plants will be studied in this project on the basis of previous study on defensive responses of host plant induced by thrips feeding. The favorite host, kidney bean, and non-favorite host, tomato will be selected as host plants. The enzymes in F. occidentalis feeding host plants in different generations were studied. The changes of activities of digestive enzymes, protective enzymes and detoxifying enzymes in F. occidentalis will be assessed by biochemical analysis, and differences of the expression of functional genes were analyzed by molecular methods. The functions of genes were analyzed by RNAi techneque, which will verify the effect of enzymes in adaptation to plant defense. The objects are to explore the adaptation differences of F. occidentalis to different preference hosts, to reveal adaptation change patterns with the generations and gradual rugulation process, and to declare evolution mechnisms of F. occidentalis adaptation to plant defenses. The results will explore co-evolution of plant defenses and herbivore counter-defenses, and provide theoretical basis of effective control on F. occidentalis.

植物与植食性昆虫在进化过程中形成了相互适应的机制，植物通过各种途径防御害虫的取食，而植食性昆虫也通过多种策略适应植物的防御反应。本项目在课题组前期研究不同寄主对西花蓟马防御反应的基础上，深入研究西花蓟马体内酶系对寄主防御反应适应的生化及分子机制。以其嗜好的菜豆和非嗜好的番茄为寄主，通过生化分析揭示西花蓟马取食不同嗜好寄主不同世代后体内消化酶、保护酶和解毒酶的活性变化；采用分子生物学的方法研究体内各种酶基因表达水平差异；通过RNA干扰（RNAi）技术进行西花蓟马体内主要酶基因的功能分析，验证各种酶在适应寄主植物防御反应中的作用。通过以上研究以期阐明西花蓟马对不同嗜好寄主适应性的差异，揭示西花蓟马寄主适应性随世代增加的变化规律及逐渐调控的过程，探讨西花蓟马对寄主防御反应适应性进化机制。研究结果将为进一步阐明寄主植物防御及害虫反防御的协同进化关系，及为有效防控西花蓟马提供理论依据。

西花蓟马是重要的入侵害虫，寄主植物广，但其对不同寄主植物的嗜食性不同。为揭示西花蓟马对不同寄主的适应机制，本项目研究了西花蓟马取食嗜食性不同的寄主植物不同世代后体内消化酶、保护酶和解毒酶活性的变化、各种酶基因的表达水平差异，通过RNA干扰（RNAi）技术对主要酶的基因进行了功能分析。结果表明西花蓟马取食嗜食的菜豆植株和非嗜食的蚕豆植株不同世代后其体内消化酶（α-淀粉酶、胰蛋白酶、类胰蛋白酶）、保护酶（过氧化氢酶CAT、过氧化物酶POD、超氧化物歧化酶SOD）、和解毒酶（羧酸酯酶CarE、谷胱甘肽-S-转移酶GSTs、细胞色素P450）的活性发生了明显的变化、变化的程度与酶的种类、西花蓟马的虫态与取食世代、不同嗜食寄主有明显的关系。取食非嗜食的番茄植株也可造成蓟马体内酶活性的快速变化。西花蓟马从菜豆豆荚转换到菜豆植株和蚕豆植株后，消化酶、保护酶和解毒酶基因均迅速产生响应，其表达量与寄主的嗜食性、自身的虫态及取食的世代相关。大多情况下取食蚕豆植株后内的表达量都显著高于取食菜豆植株的。敲除相关基因后，对西花蓟马体内酶活性、表达量、死亡率、表型、体重等有明显影响。本研究揭示了西花蓟马在不同嗜好寄主的适应性，也揭示了不同虫态适应性的异同，还明确了西花蓟马逐代适应的规律。研究结果将为进一步阐明寄主植物防御及害虫反防御的协同进化关系，及为更好的开展西花蓟马的绿色治理技术奠定了基础。