Aljbory Zainab, Aikins Michael J, Park Yoonseong, Reeck Gerald R, Chen Ming-Shun
Department of Entomology Kansas State University Manhattan KS USA.
College of Agriculture Green University of Al Qasim Iraq.
Plant Direct. 2020 Aug 14;4(8):e00246. doi: 10.1002/pld3.246. eCollection 2020 Aug.
Hessian fly is a notorious pest of wheat. Previous studies suggest that Hessian fly uses effector-based mechanisms to attack wheat plants during parasitism, but no direct evidence has been reported to support this postulation. Here, we produced recombinant proteins for five Family-1 candidate effectors and antibodies. Indirect immunostaining and western blots were carried out to examine the localization of Hessian fly Family-1 proteins in plant and insect tissues. Confocal images revealed that Family-1 putative effectors were exclusively produced in the basal region of larval salivary glands, which are directly linked to the mandibles' ducts for effector injection. The five Family-1 proteins were detected in infested host plants on western blots. Indirect immunostaining of sectioned host tissues around the feeding site revealed strikingly different localization patterns between resistant and susceptible plants. In susceptible plants, the Family-1 proteins penetrated from the feeding cell into deep tissues, indicative of movement between cells during nutritive cell formation. In contrast, the Hessian fly proteins were primarily limited to the initially attacked cells in resistant plants. The limitation of effectors' spread in resistant plants was likely due to wall strengthening and rapid hypersensitive cell death. Cell death was found in in association with hypersensitive reaction triggered by the Family-1 effector SSGP-1A2. Our finding represents a significant progress in visualizing insect effectors in host tissues and mechanisms of plant resistance and susceptibility to gall midge pests.
黑森瘿蚊是一种臭名昭著的小麦害虫。先前的研究表明，黑森瘿蚊在寄生过程中利用基于效应子的机制攻击小麦植株，但尚无直接证据支持这一假设。在此，我们制备了5种1类候选效应子的重组蛋白和抗体。进行了间接免疫染色和蛋白质免疫印迹，以检测黑森瘿蚊1类蛋白在植物和昆虫组织中的定位。共聚焦图像显示，1类假定效应子仅在幼虫唾液腺的基部区域产生，该区域直接与用于效应子注射的下颚导管相连。在蛋白质免疫印迹中，在受侵染的寄主植物中检测到了这5种1类蛋白。对取食部位周围的寄主组织切片进行间接免疫染色，结果显示抗性植物和感病植物的定位模式存在显著差异。在感病植物中，1类蛋白从取食细胞渗透到深层组织，表明在营养细胞形成过程中细胞间存在移动。相比之下，在抗性植物中，黑森瘿蚊蛋白主要局限于最初被攻击的细胞。效应子在抗性植物中的扩散受限可能是由于细胞壁强化和快速的过敏细胞死亡。在由1类效应子SSGP-1A2触发的过敏反应中发现了细胞死亡。我们的发现代表了在可视化昆虫效应子在寄主组织中的情况以及植物对瘿蚊害虫的抗性和感病性机制方面取得的重大进展。
