Abstract
Senescence is a natural, energy-dependent, physiological, developmental and an ecological process that is controlled by the plant’s own genetic program, allowing maximum recovery of nutrients from older organs for the survival of the plant, as such; it is classified as essential component of the growth and development of plants. In some cases, under one or many environmental stresses, senescence is triggered in plants. Despite many studies in the area, less consideration has been given to plant secondary metabolites, especially the role of VTCs on plant senescence. This review seeks to capture the biosynthesis and signal transduction of VTCs, the physiology of VTCs in plant development and how that is linked to some phytohormones to induce senescence. Much progress has been made in the elucidation of metabolic pathways leading to the biosynthesis of VTCs. In addition to the classical cytosolic mevalonic acid (MVA) pathway from acetyl-CoA, the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway, originating from glyceraldehyde-3-phosphate (GAP) and pyruvate, leads to the biosynthesis of isoprenoid precursors, isopentenyl diphosphate and dimethyl allyl diphosphate. VTCs synthesis and emission are believed to be tightly regulated by photosynthetic carbon supply into MEP pathway. Thus, under abiotic stresses such as drought, high salinity, high and low temperature, and low CO2 that directly affect stomatal conductance and ultimately biochemical limitation to photosynthesis, there has been observed induction of VTC synthesis and emissions, reflecting the elicitation of MEP pathway. This reveals the possibility of important function(s) of VTCs in plant defense against stress by mobilizing resources from components of plants and therefore, senescence. Our current understanding of the relationship between environmental responses and senescence mostly comes from the study of senescence response to phytohormones such as abscisic acid, jasmonic acid, ethylene and salicylic acid, which are extensively involved in response to various abiotic and biotic stresses. These stresses affect synthesis and/or signaling pathways of phytohormones to eventually trigger expression of stress-responsive genes, which in turn appears to affect leaf senescence. Comparison of plant response to stresses in relation to patterns of VTCs and phytohormones biosynthesis indicates a considerable crosstalk between these metabolic processes and their signal to plant senescence.
Highlights
Plant senescence is deemed as a complex, highly regulated, developmental phase in the life of a plant with a consequence of a coordinated degradation of macromolecules and a subsequent benefit of component mobilization from other parts of the plant [1]
This review seeks to capture the biosynthesis and signal transduction of Volatile terpene compounds (VTCs), the physiology of VTCs in plant development and how that is linked to some phytohormones to induce senescence
Our current understanding of the relationship between environmental responses and senescence mostly comes from the study of senescence response to phytohormones such as abscisic acid, jasmonic acid, ethylene and salicylic acid, which are extensively involved in response to various abiotic and biotic stresses
Summary
Plant senescence is deemed as a complex, highly regulated, developmental phase in the life of a plant with a consequence of a coordinated degradation of macromolecules and a subsequent benefit of component mobilization from other parts of the plant [1]. Does VTCs serve as a feeding deterrent to insects and some herbivores [6], it is well accepted that VTCs play a major role in plant senescence by keeping the plant healthy and protecting it against environmental stresses that are known to cause plant death [7]. They are known to be synthesized by two pathways in the cytosol, endoplasmic reticulum, peroxisomes and plastids, and stored in glandular cells of leaves and resin ducts of needles [8]. VTC synthesis and signaling pathways, its physiological role in senescence and the crosstalk between VTCs, phytohormones and plant senescence are discussed below
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
