The involvement of ABA in mediating drought stress has been extensively researched. ABA plays a critical role in regulating plant water status through guard cells and growth as well as by induction of genes that encode enzymes and other proteins involved in cellular dehydration tolerance (Luan, 2002a, Zhu, 2002).
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What is the role of ABA in drought and salt stress?
The role of ABA in drought and salt stress is twofold: water balance and cellular dehydration tolerance. genes that encode dehydration tolerance proteins in nearly all cells. ABA accumulation is inhibition of ABA degradation [46].
How does ABA work in saltwater?
ABA acts as an endogenous messenger and salt and drought stress signal transmission to initiate downstream gene expression occurs mainly via ABA signaling. signaling pathway [39]. in their promoter regions. An ABRE together with a Coupling Element (CE) results in ABA induction of gene expression [19]. The A BA R ESPONSIVE E LEMENT B INDING FACTOR
Can ABA synthesis prime for ABA-induced tolerance against drought?
ABA synthesis is important for defense signaling against salt and osmotic stress (Hasegawa et al., 2000). Since an intact ABA-signaling pathway is also necessary for BABA-induced tolerance against drought and salinity (Fig. 3), we have tested whether BABA could prime for ABA accumulation.
What is drought tolerance ABA?
ABA and drought tolerance Drought is lack of water in the soil. Drought stress in plants arises due to water deficit bilayer structure. In addition, protein denaturation and accumulation of cellular electrolytes results in disruption of cellular metabolism [63]. Therefore, drought causes osmotic stress, and
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Why is ABA important in plants?
Abscisic acid (ABA) regulates various aspects of plant physiology, including promoting seed dormancy and adaptive responses to abiotic and biotic stresses. In addition, ABA plays an im-portant role in growth and development under non-stressed conditions.
Which role of ABA protect plants?
ABA is an important regulator of plant growth, including embryo and seed development, seedling establishment, vegetative and reproductive growth as well as promoting seed dormancy [9,10]. Seed maturation and promotion of dormancy are important in preventing preharvest sprouting.
Does ABA promote water loss?
Together, these results demonstrate that a single small molecule ABA mimic can activate multiple ABA receptors and protect plants from water loss and drought stress.
How does ABA overcome stress conditions?
In case of scarcity of water, ABA gives signal to stomata. This results in stomata getting closed. Thus, transpiration is stopped and water is conserved. This explains how ABA overcomes stress situations.
How does ABA help with drought?
ABA also helps in reducing the adverse effects related to stresses in plants, such as drought. ABA enables the plant species to adapt to a continuously changing environment and maintain the physiological processes under drought stress.
How abscisic acid can help a plant survive drought stress?
The plant hormone abscisic acid (ABA) regulates drought stress responses by mediating stomatal closure, thereby reducing transpirational water loss. Exogenous ABA applications delay wilting and allow plants to survive short periods of severe drought.
What is the function of ABA?
ABA is a key hormone that regulates water status and stomatal movement. Under drought conditions, plants produce and accumulate increased amounts of ABA in the guard cells, and this induces stomatal closure to conserve water.
How ABA will be used to reduce transpiration in a plant?
A typical effect of ABA on leaves is to reduce transpirational water loss by closing stomata and parallelly defend against microbes by restricting their entry through stomatal pores. ABA can also promote the accumulation of polyamines, sphingolipids, and even proline.
How does abscisic acid acts as stress hormone in drought condition?
Abscisic acid is referred to as stress hormone as it causes different plant responses acting against stress conditions. It facilitates the seed dormancy and ensures seed germinates under favourable circumstances. It also causes the closing of stomata when there is a drought.
Why is abscisic acid is used as stress?
Abscisic acid helps the plant to survive during unfavourable conditions of the environment. It is observed that when there is a deficiency of water in leaves, ABA concentration increases and it promotes closure of stomata hence it is called stress hormone.
How increased ABA levels help plant during stress conditions?
The accumulation of ABA in maize roots helps to elongate the roots, allowing for the exploitation of surrounding soil environments and contributing to the plants ability to cope of with water stress. Also, ABA may act in root meristem maintenance (Liang et al., 2007).
What is the role of abscisic acid ABA in plant roots when the soil is dry?
This review has necessarily focused on abscisic acid (ABA), as there is little information about the role of other hormones in controlling growth in dry or saline soils. ABA is partly responsible for the differential response of root and shoot growth to dry soils.
What is ABA in plants?
... ABA, an isoprenoid class of plant hormones, is well known as an antistress phytohormone which can rapidly accumulate under environmental stresses [124]. It is wellknown that ABA can stimulate stomatal closure. ...
What are the abiotic stresses that affect agriculture?
Abiotic stresses, which include heavy metal, drought, salinity, cold and heat stress are a severe threat to agricultural ecosystems which greatly hampers the crop productivity and also deteriorates the environment. It was estimated that worldwide, these stresses are responsible for reduction of average yield of various major crops by more than 50%. These stresses cause many morphological, physiological, biochemical and molecular alterations that finally leads to loss of productivity and degradation of ecosystem. Climatic changes and excessive use of fertilizers and pesticides in modern agricultural practices to increase production worsen the effects of these abiotic stresses. Only 0.1% of the applied pesticides reach the target organism, while the residual contaminates the soil and decreases growth, productivity of crop and also alters the biological and chemical properties of the soil. Furthermore, increase and expansion of human population with time has caused degradation of habitats, increased pollution and increased salinization of agricultural fields. All the stresses mentioned above are often interconnected and these are known to initiate similar cellular damage, e.g. both, drought and salinity stress which are principally shown as osmotic stress, brings about the change in cell homeostasis and ion dispersal in the cell. High temperature causes denaturation and accumulation of deoxyribonucleic acid (DNA), cellular proteins, causes induction of thermo tolerance and accumulation of heat shock proteins (hsps) whereas low temperature impairs many metabolic processes, modifies membrane properties, changes structure of proteins and inhibits enzymatic activity. Heavy metals (HMs) like arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), mercury (Hg) and nickel (Ni) interferes with photosynthesis, water and mineral uptake and also causes modification of amino acids, proteins, deoxyribonucleic acid (DNA) and cell membrane damage. All plants are considered capable of recognizing and responding to these stresses. Common plant responses against these stresses include altering water transport, production of different osmolytes and scavenging of harmful reactive oxygen species (ROS) by action of different enzymatic and non-enzymatic antioxidants.
What is the role of nitric oxide in drought?
Nitric oxide (NO), a water- and lipid-soluble free radical, plays an important role in cytoprotection. Apart from a few studies supporting the role of NO in drought responses, little is known about this pivotal molecular amendment in the regulation of abiotic stress signaling. In this review, we highlight the knowledge gaps in NO roles under drought stress and the technical challenges underlying NO detection and measurements, and we provide recommendations regarding potential avenues for future investigation. The modulation of NO production to alleviate abiotic stress disturbances in higher plants highlights the potential of genetic manipulation to influence NO metabolism as a tool with which plant fitness can be improved under adverse growth conditions.
How does abiotic stress affect plants?
Abiotic stress, a collection of environmental factors including anthropogenic ones, which adversely affects the plant growth and productivity , are becoming a major concern in the coming decades. Plants continuously evolved with the changing environment and adopted several strategies to tolerate abiotic stress. Plant hormones collectively play a pivotal role in imparting resistance in the plant against abiotic stress. Additionally, several plant-associated bacteria also assist the plant to withstand abiotic stress to various extents through hormonal or nonhormonal pathways. Current knowledge on understanding biosynthesis of plant hormones, its regulation, and its use in modulating host plants response to abiotic stress by bacteria is limited. Hence, in the present chapter, we are attempting to fulfill the knowledge gap and discuss its further application in improving crop productivity sustainably.
How does salinity affect food security?
Drought and salinity are major abiotic stress which not only reduces crop productivity of vegetable crops but also affects food security, especially in the present time when the population is increasing at a higher pace . It is well evident that vegetable crops as other crops have developed vibrant responses through modifications at the morphological, biochemical, and physiological levels which allow them to get away to adapt or counter the adverse ecological conditions. Among these abiotic stress factors, salinity and heat stress are the major ones. Several studies reported that conditions such as salinity, increased in temperature and drought, can lower the crop yields up to 50% of the normal. There is a response of plants towards the stress of salinity and drought which involves functions such as signaling, plant growth regulators, transcription factors, production of hormones, and secondary metabolites. Controlling of agronomical practices and information technology in vegetable crop growing apart from the biotechnological tools helps to mitigate salinity and drought stress. This chapter presents compiled information on the form of stress i.e. salinity and drought stress about vegetable crops and mitigation strategies to combat the same.
What is the most important signal transduction pathway among all the plant responses to stress?
Since ABA mediates so many stress responses, the initial perception of dehydration and the subsequent changes in gene expression that lead to rapid ABA biosynthesis constitute the most important stress signal transduction pathway among all the plant responses to stresses.
Why are marginal areas important for agriculture?
These marginal areas commonly impose various types of stresses on crops due to factors such as salinity, soil water deficit, temperature extremes, flooding, low nutrients, and aluminum or heavy metal toxicity. As a consequence, the growth and yield of crops from such areas is typically low and their quality is poor, limiting farmer income. Endogenous plant growth regulators play an important role in regulating plant responses to above-mentioned stresses by sensitizing growth and developmental processes. While the physiological and molecular mechanisms linked to the role of abscisic acid and cytokinins in stress tolerance are well explained, there is growing interest to elucidate the associations of auxins, ethylene, gibberellins, brassinosteroids, and polyamines in water deficit tolerance mechanism and also on possible cross-talk mechanism among different growth regulators during tolerance acquisition. Identification and characterization of the gene regulating synthesis of different endogenous growth regulators and recent progresses on hormonal signaling, mutant research, and physiological actions have provided scope for manipulating their biosynthetic pathways for developing transgenic crop plants with enhanced abiotic stress tolerance. Researches have also provided some leads in exploiting the potential of growth regulators in enhancing the resistance to abiotic stresses of crops. Plant growth regulators are chemical compounds that stimulate plant growth and productivity when applied, even in small quantities at appropriate plant growth stages. These are being extensively used in agriculture to enhance the productivity in agricultural crops. Their central role in plant growth and development is through nutrient allocation and source–sink transitions while most of the plant bio-regulators stimulate redox signaling under abiotic stress conditions.
What is the role of ABA in drought?
ABA accumulates under osmotic stress conditions and plays an important role in the stress response and tolerance of plants.
What is the role of aba in plants?
ABA also plays a major role in mediating physiological responses to environmental stresses such as salt, osmotic, and cold stress.
What is the function of ABA signaling in plants?
Although ABA has a broad range of functions in plant growth and development, its main function is to regulate plant water balance and osmotic stress tolerance [ 11 ]. Thus, understanding ABA signaling is essential to improving plant performance.
Why is ABA important?
Seed maturation and promotion of dormancy are important in preventing preharvest sprouting. In addition, ABA has the ability to antagonize the germination promoting effects of gibberellin, regulate guard cells, and regulate stress-responsive gene expression under water-deprived conditions.
What is the role of abscisic acid in plants?
Abscisic acid (ABA) is a phytohormone with roles at various stages of plant development. ABA also plays a major role in mediating physiological responses to environmental stresses such as salt, osmotic, and cold stress. Plant responses to environmental stress have been widely studied in the model plant Arabidopsis thaliana ...
Is a plant's response to environmental stress ABA-dependent or ABA-independent?
In general, the adaptive responses of plants to various stress conditions can be either ABA-dependent or ABA-independent.
Does ABA increase with stress?
ABA in stress signaling. In plants and other organisms, such as algae, cyanobacteria, and fungi, ABA levels tend to increase with exposure to stress, suggesting a potential role of ABA in stress signal transduction [ 20 ].
Abstract
The exploration of plant response to drought stress is a key to understanding the mechanisms of the drought signaling network and further implementing the knowledge in breeding programs of crops. Plant hormones are crucial factors in transducing the stress signal and the main player among them is abscisic acid (ABA).
Abbreviations
The detoxification efflux carriers/multidrug and toxic compound extrusion 50
Notes
This work was supported by the European Regional Development Fund through the Innovative Economy for Poland 2007–2013, project WND-POIG.01.03.01-00-101/08 POLAPGEN-BD “Biotechnological tools for breeding cereals with increased resistance to drought,” task 22.