Digestion of the Caterpillar Midgut by a Maize Defense Protease

Dawn Sywassink LutheIOS-0641219玉米防御蛋白对毛虫中肠的消化每年世界上大约15%的农作物被昆虫食草动物所损失。 这种损害大部分是由于鳞翅目或毛虫害虫，科学家们正在不断寻找环境友好，非化学方法来控制它们。 以前的研究使用对秋粘虫具有遗传抗性的玉米品系，已经确定了玉米用来阻止食草动物的一种新型防御。为了应对毛虫的攻击，半胱氨酸蛋白酶在毛虫取食部位的植物中积累。 这种蛋白酶类似于木瓜蛋白酶，木瓜蛋白酶是一种存在于肉类嫩化剂中的蛋白质降解酶。 这种称为Mir 1-CP的防御性蛋白酶已被证明可以攻击和降解秋粘虫和其他毛虫的围食膜（PM）。 PM沿着中肠排列，包围食物团，保护昆虫的消化道免受毒素和病原体的侵害。这是最佳的养分利用和PM中断往往导致毛虫死亡。该项目将确定在几种经济上重要的毛虫害虫中是否存在对Mir 1-CP的敏感性差异。它将确定PM蛋白组成是否有助于抵抗或敏感性Mir 1-CP攻击。 最后，它将确定毛毛虫是否能够从暴露于含有Mir 1-CP的饮食中恢复过来。蛋白质组学和分子生物学技术将被用来实现这一目标。这些目标直接解决了该项目的更广泛影响之一：对这种天然宿主植物防御机制有一个正确的理解，以便它可以用于控制玉米和其他作物中的毛虫害虫。该项目的教育部分包括征聘代表性不足的少数民族加入实验室小组，以获得第一手研究经验。

Dawn Sywassink LutheIOS-0641219Digestion of the Caterpillar Midgut by a Maize Defense ProteaseEach year approximately 15% of the world's crops are lost to insect herbivory. Much of this damage is due to Lepidopteran or caterpillar pests and scientists are continually searching for environmentally friendly, non-chemical methods to control them. Previous research using corn lines that are genetically resistant to fall armyworm has identified a novel defense that corn uses to deter herbivores. In response to caterpillar attack, a cysteine protease accumulates in the plant at the caterpillar-feeding site. This protease is similar to papain, the protein-degrading enzyme that is present in meat tenderizers. This defensive protease, called Mir1-CP, has been shown to attack and degrade the peritrophic membrane (PM) of the fall armyworm and other caterpillars. The PM lines the midgut, surrounds the food bolus and protects the insect's digestive track from toxins and pathogens. It is essential for optimal nutrient utilization and PM disruption often results in caterpillar death. This project will determine if there are differences in susceptibility to Mir1-CP among several economically important caterpillar pests. It will determine if PM protein composition contributes to resistance or susceptibility to Mir1-CP attack. Finally, it will determine if the caterpillar is able to recover from exposure to diets containing Mir1-CP. The techniques of proteomics and molecular biology will be used to accomplish the objectives. These objectives directly address one of the broader impacts of this project: to develop a sound understanding of this natural host-plant defense mechanism so that it can be used to control caterpillar pests in corn and other crops. Educational components of the project include recruitment of underrepresented minorities to the laboratory group so as to gain first-hand research experience.