Oxidative post-translational modifications in plant-insect interactions

由于对农业用地的需求不断增加，以供应粮食和生物燃料作物，因此需要提高植物生产力。减少由于昆虫植食性造成的作物损失是维持或增加植物生产力的重要途径，特别是因为预计随着全球变暖的进展，未来毛虫害虫造成的农业损失将增加。 植物有多种机制来保护自己免受毛虫的捕食。然而，昆虫食草动物也有策略来抵消或解毒这些植物防御。例如，一些毛虫在其唇唾液中含有效应物，其可以延迟或抑制植物诱导的防御。夜蛾是全球广泛分布的食草动物，包括农业，生物燃料和园艺物种。当它们以植物为食时，它们分泌唾液，导致植物防御能力降低。利用最先进的分子和生物化学技术，我们正在研究这一机制，目标是制定可持续的农业害虫管理战略。 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，不涉及基因表达。因此，其他细胞调节机制，如蛋白质翻译后修饰（PTM），必须参与。多面手毛虫唇唾液含有酶，如产生过氧化氢的葡萄糖氧化酶;这种活性氧物质可能介导细胞蛋白质的PTM，特别是氨基酸修饰，如半胱氨酸氧化或半胱氨酸谷胱甘肽化。这种氧化应激相关的PTM已被确定在其他系统中，然而，鲜为人知的是，这些活性氧物种相关的PTM在植物-昆虫相互作用中的作用。因此，我们建议通过鉴定和表征活性氧介导的蛋白质PTM来阐明通性拟谷盗幼虫破坏诱导植物防御的机制。 此外，我们以前确定毛虫唇唾液脂氧合酶2，茉莉酸生物合成的关键酶特异性去磷酸化。PTM对脂氧合酶2活性的调节为毛虫唇唾液介导的诱导植物防御的抑制提供了一种很好的手段。因此，以及活性氧物种相关的PTM，我们将在植物-昆虫相互作用的特点脂氧合酶2去磷酸化。 通过阐明蛋白质PTM网络响应于毛虫植食性，我们希望了解唇唾液如何颠覆植物防御，并确定育种计划的内源性目标，以提高植物对咀嚼昆虫植食性的抗性。通过这项研究，4名研究生（2名博士和2名硕士），5名本科生和一名兼职研究技术人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产业（如农业和生物技术）的高需求领域。

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.