Since recent history, there have been tremendous efforts in combating the challenges of food insecurity. This mini-review discusses how environmental conditions favour or impair the growth and survival of plants via the molecular mechanisms of the secondary metabolites. Like animals, plants have survived many eons by evolving adaptive mechanisms in the presence of the myriad of abiotic and biotic stressors. In this text, the subject of drought and salt content in relationship to their role in biosynthesis of secondary metabolites is being discussed.
Fundamentally, plants require optimum concentrations of microfauna/ micronutrients and favourable climatic/edaphic conditions in their metabolism. Consequently, they produce primary metabolites (such as carbohydrates, amino acids among others) that are needed for the normal growth and reproduction of plants.
On the other hand, the secondary metabolites are mostly needed for ecological functions and regulating the primary metabolic pathways. Plants via their diverse pathways (TCA cycle, MEP pathway, shikimic pathway, mevalonate pathways) have been found to produce secondary metabolites such as terpenes, phenolic and nitrogen-based compounds. These secondary metabolites have been linked to affect crop yield and medicinal properties of plants in addition to other applications. Through well-controlled machinery of signal transduction; in response to ionic and osmotic balances, the biosynthesis of secondary metabolites has been known to be induced or inhibited for the growth and survival of the plant species.
Table of Contents
1.1 Introduction
1.2 Definition of salinity
1.3 How to measure salinity
1.4 Definition of Drought
1.4.1 Causes of drought
1.4.2 Types of drought
1.4.3 Consequences of drought
2.1 Definition of metabolite
2.1.1 Examples of metabolite
2.1.2 Types of metabolite
2.2 Primary metabolite
2.3 Secondary metabolite
3.1 Plant Physiology and Metabolism
3.2 Role of Secondary metabolites
4.1 Antioxidant system and Plant metabolism
4.2 Environmental stressors
4.3 Free radicals / Reactive Oxygen Species (ROS)
4.4 Effect of Drought on Plant Physiology and Metabolism
4.5 Effect of Salinity on Plant Physiology and Metabolism
4.6 Relationship between drought and Salinity
4.7 Effect of drought and salinity on Secondary Metabolites
Research Objectives and Topics
This literature review explores the complex physiological and metabolic responses of plants when subjected to abiotic stresses, specifically drought and salinity. The primary objective is to synthesize existing scientific knowledge regarding how these environmental stressors impact plant development, photosynthetic efficiency, and the subsequent synthesis and accumulation of secondary metabolites as protective mechanisms.
- Mechanisms of abiotic stress perception and signaling in plants.
- Impact of drought and salinity on primary metabolism and photosynthetic machinery.
- Role of reactive oxygen species (ROS) and antioxidant defense systems.
- Biosynthesis pathways and classification of plant secondary metabolites.
- Environmental regulation of secondary metabolite accumulation in response to stress.
Excerpt from the Book
3.1 Plant Physiology and Metabolism
Plants have the most sophisticated chemical system in the world (Stitt et al., 2010). They use light energy to convert CO2 into carbohydrates in their leaves. They absorb nutrients like nitrate, phosphate, and sulfate via their roots and convert them to amino acids and nucleotides, using light energy in the leaves in the day and energy derived from respiration in leaves in the dark and in non-photosynthetic tissues. Carbohydrates, amino acids, and nucleotides are then transported to growing tissues, where they are converted into macromolecular cellular components like proteins, nucleic acids, cell walls, pigments, and lipids.
Plants also synthesize a number of secondary metabolites, including phenylpropanoids and flavonoids, terpenoids, glucosinolates, and alkaloids (Stitt et al., 2010). These have important roles in cellular function, in signaling, and in adaptation to abiotic and biotic stress. Their unique synthetic ability is the result of a highly complex and sophisticated metabolic apparatus. Previous report has pointed out the complexity and flexibility of plants as revealed in the discoveries of several pathways like glycolysis, the oxidative pentose phosphate pathway, and organic acid metabolism, present in more than one compartment (Lunn, 2007). This is in addition to the unveiling of the diversity of plant secondary metabolite.
Plants metabolites are known to be unique sources for pharmaceuticals food additives, flavors and others industrial values (Tiwari and Rana, 2015).
Summary of Chapters
CHAPTER ONE: This chapter introduces the global challenges of food security caused by environmental stressors, defining abiotic and biotic stresses and their detrimental impact on plant growth and yield.
CHAPTER TWO: This section defines the fundamental concepts of plant metabolites, distinguishing between primary metabolism, which is essential for survival, and secondary metabolism, which plays a pivotal role in plant defense.
CHAPTER THREE: This chapter elaborates on the sophisticated metabolic apparatus of plants, detailing the roles and classifications of secondary metabolites such as terpenes, phenolics, and nitrogen-containing compounds.
CHAPTER FOUR: This chapter analyzes the oxidative damage induced by environmental stressors and the corresponding antioxidant defense systems, specifically examining how drought and salinity influence plant physiology and the accumulation of secondary compounds.
Keywords
Abiotic stress, Salinity, Drought, Plant Metabolism, Secondary Metabolites, Antioxidant Defense, Reactive Oxygen Species, Photosynthesis, Signal Transduction, Terpenes, Phenolic Compounds, Osmotic Adjustment, Crop Yield, Environmental Stressors, Oxidative Damage.
Frequently Asked Questions
What is the core subject of this publication?
The publication is a comprehensive literature review focusing on how two major environmental stressors, drought and salinity, affect the physiology and metabolic processes of plants, particularly regarding the production of secondary metabolites.
What are the central thematic areas covered in the text?
The key themes include the mechanisms of plant abiotic stress, the role of reactive oxygen species (ROS) in plant cells, the distinction between primary and secondary metabolites, and the signaling pathways plants use to adapt to adverse environmental conditions.
What is the primary objective of this review?
The goal is to provide a holistic understanding of how plants manage stress-induced damage and how this stress leads to the up-regulation of secondary metabolites, which are essential for plant defense and have potential economic value.
Which scientific methods are discussed in the context of research?
The text refers to various physiological and biochemical methods, including photosynthesis measurements, electrolyte analysis, antioxidant enzyme assays (such as SOD and CAT activity), and metabolite profiling under stress conditions.
What content is addressed in the main body of the work?
The main body examines the definitions of drought and salinity, the biochemical impact on photosynthesis, the oxidative stress induced by these conditions, and theories such as the Carbon/Nitrogen Balance (CNB) hypothesis regarding metabolite allocation.
Which keywords best describe this research?
Essential keywords include abiotic stress, salinity, drought, plant metabolism, secondary metabolites, and oxidative damage.
How do plants perceive drought and salinity stressors?
Plants perceive these stressors through specialized plasma membrane receptors that interact with external molecules (ligands), which then initiate signal transduction cascades involving second messengers like calcium and ROS to trigger specific gene expression.
What is the significance of the Carbon/Nitrogen Balance (CNB) hypothesis?
The CNB hypothesis suggests that the allocation of resources to secondary metabolites is governed by the relative availability of carbon and nitrogen, predicting that nutrient deficiencies influence whether a plant prioritizes growth or defense.
How does drought specifically affect plant photosynthesis?
Drought induces stomatal closure to prevent water loss, which limits CO2 availability, disrupts the electron transport chain, and leads to the generation of reactive oxygen species, ultimately impairing the photosynthetic machinery.
- Citar trabajo
- Akinmayowa Adedoyin Shobo (Autor), 2018, The effect of drought and salinity on secondary metabolite of plants, Múnich, GRIN Verlag, https://www.grin.com/document/494142
