Oxidative post-translational modifications in plant-insect interactions

由于对供应粮食和生物燃料作物的农用土地的需求日益增加，提高植物生产力的必要性从未像现在这样高。减少因昆虫食草造成的作物损失是维持或提高植物生产力的重要途径，特别是因为随着全球变暖的进展，预计未来由于毛虫虫害造成的农业损失将会增加。植物有多种机制来保护自己免受毛虫食草性疾病的侵害。然而，昆虫食草动物也有抵消或解毒这些植物防御的策略。例如，一些夜蛾毛虫的嘴唇唾液中含有效应器(S)，可以延缓或抑制植物诱导的防御。夜蛾毛虫是全球广泛分布的多种植物的草食动物，包括农业、生物燃料和园艺物种。当它们以植物为食时，它们会分泌嘴唇唾液，从而降低植物的防御能力。利用尖端的分子和生化技术，我们正在研究这一现象背后的机制，以期制定可持续的农业病虫害防治战略。当植物被毛虫伤害时，快速的生化变化会产生茉莉酸介导的防御级联反应。这些变化太快了，不涉及基因表达。因此，必须涉及其他细胞调控机制，如蛋白质翻译后修饰(PTM)。夜蛾毛虫嘴唇唾液中含有葡萄糖氧化酶等酶，可产生过氧化氢；这种活性氧物种可能介导细胞蛋白质的PTMS，特别是氨基酸修饰，如半胱氨酸氧化或半胱氨酸谷胱甘肽基化。这种与氧化胁迫相关的PTM在其他系统中也被发现；然而，关于这些与活性氧相关的PTMS在植物-昆虫相互作用中的作用，人们知之甚少。因此，我们建议通过鉴定和鉴定活性氧介导的蛋白PTM来阐明通用型夜蛾幼虫破坏诱导植物防御的机制。此外，我们以前发现毛虫嘴唇唾液中脂氧合酶2的特异性去磷酸化，这是茉莉酸生物合成的关键酶。PTM对脂氧合酶2活性的调节为毛虫唾液介导的抑制诱导的植物防御提供了一种很好的方法。因此，除了与活性氧物种相关的PTM外，我们还将研究植物-昆虫相互作用中脂氧合酶2去磷酸化的特征。通过阐明毛虫食草性反应的蛋白质PTM网络，我们希望了解唇状唾液如何颠覆植物的防御系统，并为提高植物对咀嚼昆虫食草性的抗性育种寻找内源靶标。通过这项研究，4名研究生(2名博士和2名硕士)、5名本科生和1名兼职研究技术员将获得植物分子生物学和生理学方面的专业知识，这些领域是加拿大重要行业的高需求领域，如农业和生物技术。

Due to the increasing demands on agricultural lands to supply food as well as biofuels crops, the need to increase plant productivity has never been higher. The reduction of crop losses due to insect herbivory is an important way to maintain or increase plant productivity, particularly since agricultural losses to caterpillar pests are predicted to increase in the future as global warming progresses. Plants have multiple mechanisms to protect themselves against caterpillar herbivory. However, insect herbivores also have strategies to counteract or detoxify these plant defenses. For example, some noctuid caterpillars contain effector(s) in their labial saliva that can delay or suppress plant induced defenses. Noctuid caterpillars are globally-widespread herbivores of many plants, including agricultural, biofuel and horticultural species. When they feed on the plant, they secrete labial saliva that results in the lowering of plant defenses. Using cutting-edge molecular and biochemical techniques, we are studying the mechanisms underlying this with the goal of developing sustainable agricultural pest management strategies. When plants are wounded by caterpillars, rapid biochemical changes generate a jasmonate-mediated defensive cascade. These changes are too rapid to involve gene expression. Therefore, other cellular regulatory mechanisms, such as protein post-translational modifications (PTMs), must be involved. Generalist noctuid caterpillar labial saliva contains enzymes, such as glucose oxidase that generates hydrogen peroxide; this reactive oxygen species may mediate the PTMs of cellular proteins, specifically amino acid modifications such as cysteine-oxidation or cysteine-glutathionylation. Such oxidative stress-related PTMs have been identified in other systems; however, little is known about the role of these reactive oxygen species-related PTMs in plant-insect interactions. Therefore, we propose to elucidate the mechanisms used by generalist noctuid larva to undermine induce plant defenses by identifying and characterizing reactive oxygen species-mediated protein PTMs. In addition, we previously identified caterpillar labial saliva-specific dephosphorylation of lipoxygenase 2, a key enzyme in jasmonate biosynthesis. Regulation of lipoxygenase 2 activity by PTM provides an excellent means of caterpillar labial saliva-mediated suppression of induced plant defenses. Therefore, as well as reactive oxygen species-associated PTMs, we will characterize lipoxygenase 2 dephosphorylation in plant-insect interactions. By elucidating protein PTM networks in response to caterpillar herbivory, we hope to understand how labial saliva subverts plant defenses and identify endogenous targets for breeding programs to enhance plant resistance to chewing insect herbivory. Through this research, 4 graduate students (2 PhD and 2 MSc), 5 undergraduates and a part-time research technician will gain expertise in plant molecular biology and physiology, areas of high demand in vital Canadian industries, such as agriculture and biotechnology.