Kutty Nithya N, Mishra Manasi
Department of Biosciences and Technology, Dr. Vishwanath Karad MIT-World Peace University, Pune, Maharashtra, India.
Front Plant Sci. 2023 Jun 19;14:1135000. doi: 10.3389/fpls.2023.1135000. eCollection 2023.
Plants are continuously threatened by a plethora of biotic stresses caused by microbes, pathogens, and pests, which often act as the major constraint in crop productivity. To overcome such attacks, plants have evolved with an array of constitutive and induced defense mechanisms- morphological, biochemical, and molecular. Volatile organic compounds (VOCs) are a class of specialized metabolites that are naturally emitted by plants and play an important role in plant communication and signaling. During herbivory and mechanical damage, plants also emit an exclusive blend of volatiles often referred to as herbivore-induced plant volatiles (HIPVs). The composition of this unique aroma bouquet is dependent upon the plant species, developmental stage, environment, and herbivore species. HIPVs emitted from infested and non-infested plant parts can prime plant defense responses by various mechanisms such as redox, systemic and jasmonate signaling, activation of mitogen-activated protein (MAP) kinases, and transcription factors; mediate histone modifications; and can also modulate the interactions with natural enemies direct and indirect mechanisms. These specific volatile cues mediate allelopathic interactions leading to altered transcription of defense-related genes, , proteinase inhibitors, amylase inhibitors in neighboring plants, and enhanced levels of defense-related secondary metabolites like terpenoids and phenolic compounds. These factors act as deterrents to feeding insects, attract parasitoids, and provoke behavioral changes in plants and their neighboring species. This review presents an overview of the plasticity identified in HIPVs and their role as regulators of plant defense in Solanaceous plants. The selective emission of green leaf volatiles (GLVs) including hexanal and its derivatives, terpenes, methyl salicylate, and methyl jasmonate (MeJa) inducing direct and indirect defense responses during an attack from phloem-sucking and leaf-chewing pests is discussed. Furthermore, we also focus on the recent developments in the field of metabolic engineering focused on modulation of the volatile bouquet to improve plant defenses.
植物不断受到微生物、病原体和害虫等大量生物胁迫的威胁，这些胁迫常常成为作物生产力的主要限制因素。为了抵御此类攻击，植物进化出了一系列组成型和诱导型防御机制——形态学、生物化学和分子机制。挥发性有机化合物（VOCs）是一类由植物自然释放的特殊代谢产物，在植物通讯和信号传导中发挥着重要作用。在植食性动物取食和机械损伤期间，植物还会释放出一种独特的挥发性混合物，通常称为植食性动物诱导的植物挥发物（HIPVs）。这种独特香气组合的成分取决于植物种类、发育阶段、环境和植食性动物种类。受侵染和未受侵染的植物部位释放的HIPVs可通过多种机制引发植物防御反应，如氧化还原、系统和茉莉酸信号传导、丝裂原活化蛋白（MAP）激酶和转录因子的激活；介导组蛋白修饰；还可以调节与天敌的相互作用——直接和间接机制。这些特定的挥发性信号介导化感相互作用，导致邻近植物中防御相关基因、蛋白酶抑制剂、淀粉酶抑制剂的转录改变，以及萜类和酚类化合物等防御相关次生代谢产物水平的提高。这些因素对取食昆虫起到威慑作用，吸引寄生蜂，并引发植物及其邻近物种的行为变化。本文综述了茄科植物中HIPVs的可塑性及其作为植物防御调节因子的作用。讨论了包括己醛及其衍生物、萜类、水杨酸甲酯和茉莉酸甲酯（MeJa）在内的绿叶挥发物（GLVs）在韧皮部吸食和叶片咀嚼害虫攻击期间诱导直接和间接防御反应的选择性释放。此外，我们还关注了代谢工程领域的最新进展，该领域专注于调节挥发性组合以提高植物防御能力。
