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Journal ArticleDOI

Role of proline under changing environments: a review.

05 Sep 2012-Plant Signaling & Behavior (Taylor & Francis)-Vol. 7, Iss: 11, pp 1456-1466
TL;DR: Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species within normal ranges, thus preventing oxidative burst in plants.
Abstract: When exposed to stressful conditions, plants accumulate an array of metabolites, particularly amino acids. Amino acids have traditionally been considered as precursors to and constituents of proteins, and play an important role in plant metabolism and development. A large body of data suggests a positive correlation between proline accumulation and plant stress. Proline, an amino acid, plays a highly beneficial role in plants exposed to various stress conditions. Besides acting as an excellent osmolyte, proline plays three major roles during stress, i.e., as a metal chelator, an antioxidative defense molecule and a signaling molecule. Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species (ROS) within normal ranges, thus preventing oxidative burst ...
Citations
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Journal ArticleDOI
TL;DR: An important additive component of plant defense system is symbiotic association with arbuscular mycorrhizal (AM) fungi, which can effectively immobilize HMs and reduce their uptake by host plants via binding metal ions to hyphal cell wall and excreting several extracellular biomolecules.
Abstract: Unprecedented bioaccumulation and biomagnification of heavy metals (HMs) in the environment have become a dilemma for all living organisms including plants. HMs at toxic levels have the capability to interact with several vital cellular biomolecules such as nuclear proteins and DNA, leading to excessive augmentation of reactive oxygen species (ROS). This would inflict serious morphological, metabolic, and physiological anomalies in plants ranging from chlorosis of shoot to lipid peroxidation and protein degradation. In response, plants are equipped with a repertoire of mechanisms to counteract heavy metal (HM) toxicity. The key elements of these are chelating metals by forming phytochelatins (PCs) or metallothioneins (MTs) metal complex at the intra- and intercellular level, which is followed by the removal of HM ions from sensitive sites or vacuolar sequestration of ligand-metal complex. Nonenzymatically synthesized compounds such as proline (Pro) are able to strengthen metal-detoxification capacity of intracellular antioxidant enzymes. Another important additive component of plant defense system is symbiotic association with arbuscular mycorrhizal (AM) fungi. AM can effectively immobilize HMs and reduce their uptake by host plants via binding metal ions to hyphal cell wall and excreting several extracellular biomolecules. Additionally, AM fungi can enhance activities of antioxidant defense machinery of plants.

721 citations


Cites background from "Role of proline under changing envi..."

  • ...[217] reported that exogenous Pro can form complex with various metals such as Cu, Cd, and Zn in which it can overcome inhibition of nitrate reductase caused by metal toxicity....

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Journal ArticleDOI
TL;DR: Over all crops a positive and significant association between OA and yield under drought stress were found in 24 out of 26 cases, considering that it is generally difficult to find a singular plant trait responsible for yield advantage of numerous crops under different drought stress conditions, this evidence is no less than remarkable as proof that OA sustains crop yieldunder drought stress.
Abstract: Osmotic adjustment (OA) and cellular compatible solute accumulation are widely recognized to have a role in plant adaptation to dehydration mainly through turgor maintenance and the protection of specific cellular functions by defined solutes. At the same time, there has been an ongoing trickle of skepticism in the literature about the role of OA in supporting crop yield under drought stress. Contrarian reviews argued that OA did not sustain turgor or that it served mainly for plant survival rather than productivity. This critical review examined 26 published studies where OA was compared with yield under drought stress in variable genotypes of 12 crops, namely, barley, wheat, maize, sorghum, chickpea, pea, pigeon pea, soybean, canola, mustard, castor bean and sunflower. Over all crops a positive and significant association between OA and yield under drought stress were found in 24 out of 26 cases. Considering that it is generally difficult to find a singular plant trait responsible for yield advantage of numerous crops under different drought stress conditions, this evidence is no less than remarkable as proof that OA sustains crop yield under drought stress.

516 citations


Cites background or methods from "Role of proline under changing envi..."

  • ...Does OA support crop yield under drought stress or not? Extensive information on the physiology, metabolism and genomics of OA in plants has been well presented and discussed in numerous recent reviews in addition to those mentioned earlier (e.g. Chen & Jian-Guo Jiang 2010; Ashraflow et al., 2011; Shabala & Shabala 2011; Hayat et al. 2012; Sanders &Arndt 2012; Slam et al. 2015)....

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  • ...…physiology, metabolism and genomics of OA in plants has been well presented and discussed in numerous recent reviews in addition to those mentioned earlier (e.g. Chen & Jian-Guo Jiang 2010; Ashraflow et al., 2011; Shabala & Shabala 2011; Hayat et al. 2012; Sanders &Arndt 2012; Slam et al. 2015)....

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Journal ArticleDOI
TL;DR: This review highlights the importance of the As-induced generation of reactive oxygen species (ROS) as well as their damaging impacts on plants at biochemical, genetic, and molecular levels.
Abstract: Environmental contamination with arsenic (As) is a global environmental, agricultural and health issue due to the highly toxic and carcinogenic nature of As. Exposure of plants to As, even at very low concentration, can cause many morphological, physiological, and biochemical changes. The recent research on As in the soil-plant system indicates that As toxicity to plants varies with its speciation in plants (e.g., arsenite, As(III); arsenate, As(V)), with the type of plant species, and with other soil factors controlling As accumulation in plants. Various plant species have different mechanisms of As(III) or As(V) uptake, toxicity, and detoxification. This review briefly describes the sources and global extent of As contamination and As speciation in soil. We discuss different mechanisms responsible for As(III) and As(V) uptake, toxicity, and detoxification in plants, at physiological, biochemical, and molecular levels. This review highlights the importance of the As-induced generation of reactive oxygen species (ROS), as well as their damaging impacts on plants at biochemical, genetic, and molecular levels. The role of different enzymatic (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase) and non-enzymatic (salicylic acid, proline, phytochelatins, glutathione, nitric oxide, and phosphorous) substances under As(III/V) stress have been delineated via conceptual models showing As translocation and toxicity pathways in plant species. Significantly, this review addresses the current, albeit partially understood, emerging aspects on (i) As-induced physiological, biochemical, and genotoxic mechanisms and responses in plants and (ii) the roles of different molecules in modulation of As-induced toxicities in plants. We also provide insight on some important research gaps that need to be filled to advance our scientific understanding in this area of research on As in soil-plant systems.

513 citations


Cites background from "Role of proline under changing envi..."

  • ...There are a variety of mechanisms through which proline can reduce the toxicity of As: (i) reducing As uptake by changing the structure of the cell wall and protecting plasma membranes [279], (ii) directly quenching As-induced ROS generation [322], (iii) increasing activities of various antioxidants, thus indirectly reducing the damage of ROS [322,323], and (iv) changing the expression of stress-related genes [324] (see Figure 2)....

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  • ...Salicylic acid has been found to increase the activities of SOD and APX enzymes in plants and provide them with tolerance against oxidative damage caused by metals [324,349,350]....

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Journal ArticleDOI
TL;DR: Proline acts as stress-related signal exhibiting cross tolerance to a range of different stresses and is found to be coupled to several key pathways such as pentose phosphate, tricarboxylic acid, or urea cycles and contributes to, i.e., purine synthesis and the phenylpropanoid pathway.
Abstract: Dramatic accumulation of proline is a common physiological response in plants exposed to various abiotic stresses. Accumulation of proline could be due to de novo synthesis, decreased degradation, lower utilization, or hydrolysis of proteins. Extensive intercellular proline transport occurs between the cytosol, chloroplasts, and mitochondria due to its compartmentalized metabolism. Although all functions of proline in stress tolerance are still a matter of debate, it is suggested that proline contributes to stabilization of sub-cellular structures, scavenging free radicals, and buffering cellular redox potential. It also chelates heavy metals, modulates cellular functions, and even triggers gene expression. Apparently, proline acts as stress-related signal exhibiting cross tolerance to a range of different stresses. Besides these significant roles, its metabolism is found to be coupled to several key pathways such as pentose phosphate, tricarboxylic acid, or urea cycles and contributes to, i.e., purine synthesis and the phenylpropanoid pathway. Although the molecular basis of regulation of proline metabolism is still largely obscure, the genetic engineering of proline content could lead to new opportunities to achieve plant stress tolerance.

429 citations


Cites background from "Role of proline under changing envi..."

  • ...…carbon reduction cycle also provides carbon in the form of erythrose-4-phosphate which together with phosphoenolpyruvate acts as precursor for phenylalanine biosynthesis via the shikimic acid pathway (Shetty 2004) and supports purine nucleotide biosynthesis, too (Hayat et al. 2012; Fig....

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Journal ArticleDOI
TL;DR: This review provides a comprehensive summary of the mechanisms of salt stress responses in plants, including salt stress-triggered physiological responses, oxidative stress, salt stress sensing and signaling pathways, organellar stress, ion homeostasis, hormonal and gene expression regulation, metabolic changes, as well as salt tolerance mechanisms in halophytes.
Abstract: Soil salinity is a major environmental stress that restricts the growth and yield of crops. Understanding the physiological, metabolic, and biochemical responses of plants to salt stress and mining the salt tolerance-associated genetic resource in nature will be extremely important for us to cultivate salt-tolerant crops. In this review, we provide a comprehensive summary of the mechanisms of salt stress responses in plants, including salt stress-triggered physiological responses, oxidative stress, salt stress sensing and signaling pathways, organellar stress, ion homeostasis, hormonal and gene expression regulation, metabolic changes, as well as salt tolerance mechanisms in halophytes. Important questions regarding salt tolerance that need to be addressed in the future are discussed.

416 citations

References
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Journal ArticleDOI
TL;DR: Key steps of the signal transduction pathway that senses ROIs in plants have been identified and raise several intriguing questions about the relationships between ROI signaling, ROI stress and the production and scavenging ofROIs in the different cellular compartments.

9,395 citations

Journal ArticleDOI
01 Jun 1998
TL;DR: A detailed account of current knowledge of the biosynthesis, compartmentation, and transport of these two important antioxidants, with emphasis on the unique insights and advances gained by molecular exploration are provided.
Abstract: To cope with environmental fluctuations and to prevent invasion by pathogens, plant metabolism must be flexible and dynamic. Active oxygen species, whose formation is accelerated under stress conditions, must be rapidly processed if oxidative damage is to be averted. The lifetime of active oxygen species within the cellular environment is determined by the antioxidative system, which provides crucial protection against oxidative damage. The antioxidative system comprises numerous enzymes and compounds of low molecular weight. While research into the former has benefited greatly from advances in molecular technology, the pathways by which the latter are synthesized have received comparatively little attention. The present review emphasizes the roles of ascorbate and glutathione in plant metabolism and stress tolerance. We provide a detailed account of current knowledge of the biosynthesis, compartmentation, and transport of these two important antioxidants, with emphasis on the unique insights and advances gained by molecular exploration.

5,450 citations

Journal ArticleDOI
TL;DR: In this review article, numerous examples of successful application of these compounds to improve plant stress tolerance are presented and a better understanding of the mechanisms of action of exogenously applied GB and proline is expected to aid their effective utilization in crop production in stress environments.

3,847 citations

Journal ArticleDOI
TL;DR: The compartmentalization of proline biosynthesis, accumulation and degradation in the cytosol, chloroplast and mitochondria is discussed and the role of prolines in cellular homeostasis, including redox balance and energy status, is described.

3,102 citations

Journal ArticleDOI
TL;DR: This review lists some candidate genes for salinity tolerance, and draws together hypotheses about the functions of these genes and the specific tissues in which they might operate.
Abstract: Salinity tolerance comes from genes that limit the rate of salt uptake from the soil and the transport of salt throughout the plant, adjust the ionic and osmotic balance of cells in roots and shoots, and regulate leaf development and the onset of senescence. This review lists some candidate genes for salinity tolerance, and draws together hypotheses about the functions of these genes and the specific tissues in which they might operate. Little has been revealed by gene expression studies so far, perhaps because the studies are not tissue-specific, and because the treatments are often traumatic and unnatural. Suggestions are made to increase the value of molecular studies in identifying genes that are important for salinity tolerance.

2,625 citations

Trending Questions (2)
Why is proline important for turgur pressure regulation in plant?

Proline is important for turgor pressure regulation in plants as it helps maintain cell turgor or osmotic balance under stressful conditions.

What is the role of proline as a small-molecule metabolite biomarker?

The role of proline as a small-molecule metabolite biomarker is to act as an osmolyte, metal chelator, antioxidative defense molecule, and signaling molecule in plants under stress.