Li-Byarlay Hongmei, Pittendrigh Barry R, Murdock Larry L
Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA.; The W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, USA.
Department of Entomology, Michigan State University, Natural Science Building, East Lansing MI, USA.
Int J Insect Sci. 2016 Aug 29;8:71-9. doi: 10.4137/IJIS.S28595. eCollection 2016.
Plants produce proteins such as protease inhibitors and lectins as defenses against herbivorous insects and pathogens. However, no systematic studies have explored the structural responses in the midguts of insects when challenged with plant defensive proteins and lectins across different species. In this study, we fed two kinds of protease inhibitors and lectins to the fruit fly Drosophila melanogaster and alpha-amylase inhibitors and lectins to the cowpea bruchid Callosobruchus maculatus. We assessed the changes in midgut cell structures by comparing them with such structures in insects receiving normal diets or subjected to food deprivation. Using light and transmission electron microscopy in both species, we observed structural changes in the midgut peritrophic matrix as well as shortened microvilli on the surfaces of midgut epithelial cells in D. melanogaster. Dietary inhibitors and lectins caused similar lesions in the epithelial cells but not much change in the peritrophic matrix in both species. We also noted structural damages in the Drosophila midgut after six hours of starvation and changes were still present after 12 hours. Our study provided the first evidence of key structural changes of midguts using a comparative approach between a dipteran and a coleopteran. Our particular observation and discussion on plant-insect interaction and dietary stress are relevant for future mode of action studies of plant defensive protein in insect physiology.
植物会产生诸如蛋白酶抑制剂和凝集素等蛋白质，作为抵御食草昆虫和病原体的防御手段。然而，尚无系统研究探讨不同物种的昆虫中肠在受到植物防御蛋白和凝集素挑战时的结构反应。在本研究中，我们给果蝇（Drosophila melanogaster）喂食了两种蛋白酶抑制剂和凝集素，并给豇豆象（Callosobruchus maculatus）喂食了α-淀粉酶抑制剂和凝集素。我们通过将它们与接受正常饮食或禁食的昆虫的中肠细胞结构进行比较，来评估中肠细胞结构的变化。利用光镜和透射电镜对这两个物种进行观察，我们在果蝇中观察到中肠围食膜的结构变化以及中肠上皮细胞表面微绒毛缩短。饮食中的抑制剂和凝集素在两个物种的上皮细胞中都造成了类似的损伤，但在围食膜中变化不大。我们还注意到果蝇中肠在饥饿6小时后出现结构损伤，并且在12小时后仍有变化。我们的研究首次通过双翅目和鞘翅目之间的比较方法，提供了中肠关键结构变化的证据。我们对植物 - 昆虫相互作用和饮食压力的具体观察和讨论，对于未来植物防御蛋白在昆虫生理学中的作用方式研究具有重要意义。
