Digestion of the Caterpillar Midgut by a Maize Defense Protease

玉米防御蛋白对毛虫中肠的消化世界上每年大约有15%的农作物被昆虫食草所吞噬。这种破坏大部分是由鳞翅目或毛虫害虫造成的，科学家们一直在寻找对环境友好的、非化学的方法来控制它们。先前的研究使用了对秋粘虫具有遗传抗性的玉米品系，发现了一种新的防御方法，玉米可以用来阻止食草动物。作为对毛毛虫攻击的反应，一种半胱氨酸蛋白酶在毛毛虫取食部位的植物中积累。这种蛋白酶与木瓜蛋白酶类似，木瓜蛋白酶是一种存在于肉嫩化剂中的蛋白质降解酶。这种防御性蛋白酶，被称为Mir1-CP，已经被证明可以攻击和降解秋粘虫和其他毛虫的营养膜（PM）。PM排列在中肠，包围食物丸，保护昆虫的消化道免受毒素和病原体的侵害。它对优化养分利用至关重要，PM破坏通常会导致毛虫死亡。该项目将确定几种经济上重要的毛虫害虫对Mir1-CP的易感性是否存在差异。它将确定PM蛋白组成是否有助于对Mir1-CP攻击的抗性或易感性。最后，它将确定毛虫是否能够从暴露于含有Mir1-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于实现这一目标。这些目标直接解决了这个项目的一个更广泛的影响：发展对这种天然寄主-植物防御机制的充分理解，以便它可以用于控制玉米和其他作物的毛虫害虫。该项目的教育部分包括招募代表性不足的少数民族加入实验室小组，以便获得第一手的研究经验。

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.