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Journal ArticleDOI

Role of Secondary Metabolites and Brassinosteroids in Plant Defense Against Environmental Stresses

01 Mar 2013-Journal of Plant Growth Regulation (Springer-Verlag)-Vol. 32, Iss: 1, pp 216-232
TL;DR: The present review focuses on current understanding of how plants respond to the generation of excessive ROS and the role of secondary metabolites and brassinosteroids in countering the adverse effects of environmental stresses.
Abstract: Being sessile, plants are subjected to a diverse array of environmental stresses during their life span. Exposure of plants to environmental stresses results in the generation of reactive oxygen species (ROS). These activated oxygen species tend to oxidize various cellular biomolecules like proteins, nucleic acids, and lipids, a process that challenges the core existence of the cell. To prevent the accumulation of these ROS and to sustain their own survival, plants have developed an intricate antioxidative defence system. The antioxidative defence system comprises various enzymatic and nonenzymatic molecules, produced to counter the adverse effect of environmental stresses. A sizable number of these molecules belong to the category of compounds called secondary metabolites. Secondary metabolites are organic compounds that are not directly involved in the growth and development of plants but perform specialized functions under a given set of conditions. Absence of secondary metabolites results in long-term impairment of the plant’s survivability. Such compounds generally include pigments, phenolics, and so on. Plant phenolic compounds such as flavonoids and lignin precursors have been reported to accumulate in response to various biotic and abiotic stresses and are regarded as crucial defence compounds that can scavenge harmful ROS. Another important category of plant metabolites, called brassinosteroids, exhibit stress regulatory and growth-promoting activity and are classified as phytohormones. Elucidation of the physiological and molecular effects of secondary metabolites and brassinosteroids have catapulted them as highly promising and environment-friendly natural substances, suitable for wider application in plant protection and crop yield promotion. The present review focuses on our current understanding of how plants respond to the generation of excessive ROS and the role of secondary metabolites and brassinosteroids in countering the adverse effects of environmental stresses.
Citations
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Journal ArticleDOI
TL;DR: The results of these reviews can know how developmental and environmental factors qualitatively and quantitatively influence SMs of medicinal plants and how these can be integrated as tools to quality control, as well as on the improvement of clinical curative effects by altering their genomes, and/or growth conditions.

414 citations

Journal ArticleDOI
TL;DR: Biostimulants are plant extracts that contain a wide range of bioactive compounds that are mostly still unknown and are usually able to improve the nutrient use efficiency of the plant and enhance tolerance to biotic and abiotic stresses as discussed by the authors.
Abstract: Agricultural growing practices have been evolving towards organic, sustainable or environmental friendly systems The aim of modern agriculture is to reduce inputs without reducing the yield and quality These goals can be achieved by breeding programmes but would be species specific and time consuming The identification of organic molecules able to activate plant metabolism may allow an improvement in plant performance in a short period of time and in a cheaper way Biostimulants are plant extracts and contain a wide range of bioactive compounds that are mostly still unknown These products are usually able to improve the nutrient use efficiency of the plant and enhance tolerance to biotic and abiotic stresses In this review, the state of the art and future prospects for biostimulants are reported and discussed Moreover, particular attention has been paid to intensive agricultural systems such as horticultural and floricultural crops In vegetables, the application of biostimulants allowed a reduction

347 citations


Cites background from "Role of Secondary Metabolites and B..."

  • ...They are involved in the mechanisms of interaction between plants and the environment and have a pivotal role in plant defence responses to biotic or abiotic stresses by acting as phytoalexins, signal molecules and antioxidants (Kliebenstein 2004; Bartwal et al. 2013)....

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Journal ArticleDOI
TL;DR: In this paper, the effects of heavy metal-induced reactive oxygen species (ROS) on plant cell wall-related processes and the stimulatory/inhibitory effects of ROS on plant secondary metabolism were investigated.

254 citations

Journal ArticleDOI
TL;DR: It is clearly evident that CAT, ascorbate-glutathione cycle and SOD played a significant activity in ROS detoxification of tolerant A. tricolor variety.
Abstract: The study was performed to explore physiological, non-enzymatic and enzymatic detoxification pathways of reactive oxygen species (ROS) in tolerance of Amaranthus tricolor under drought stress. The tolerant genotype VA13 exhibited lower reduction in growth, photosynthetic pigments, relative water content (RWC) and negligible increment in electrolyte leakage (EL), lower increment in proline, guaiacol peroxidase (GPOX) activity compared to sensitive genotype VA15. This genotype also had higher catalase (CAT), superoxide dismutase (SOD), remarkable and dramatic increment in ascorbate-glutathione content, ascorbate-glutathione redox and ascorbate-glutathione cycle enzymes activity compared to sensitive genotype VA15. The negligible increment of ascorbate-glutathione content, ascorbate-glutathione redox and ascorbate-glutathione cycle enzymes activities and dramatic increment in malondialdehyde (MDA), hydrogen peroxide (H2O2) and EL were observed in the sensitive genotype VA15. SOD contributed superoxide radical dismutation and CAT contributed H2O2 detoxification in both sensitive and tolerant varieties, however, these had a great contribution in the tolerant variety. Conversely, proline and GPOX accumulation were higher in the sensitive variety compared to the tolerant variety. Increase in ascorbate-glutathione cycle enzymes activities, CAT, ascorbate-glutathione content, SOD, and ascorbate-glutathione redox clearly evident that CAT, ascorbate-glutathione cycle and SOD played a significant activity in ROS detoxification of tolerant A. tricolor variety.

205 citations

Journal ArticleDOI
TL;DR: The increased content of ascorbic acid indicated the crucial role of the ASC–GSH cycle for scavenging ROS in A. tricolor cultivar, and positive correlations among MDA, H2O2, compatible solutes, and non-enzymatic antioxidant suggested that compatible solute andnon-enzysmatic antioxidant played vital role in detoxifying of ROS in the cultivar.
Abstract: Four selected Amaranthus tricolor cultivars were grown under four irrigation regimes (25, 50, 80, and 100% field capacity) to evaluate the mechanisms of growth and physiological and biochemical responses against drought stress in randomized complete block design with three replications. Drought stress led to decrease in total biomass, specific leaf area, relative water content (RWC), photosynthetic pigments (chlorophyll a, chlorophyll b, chlorophyll ab), and soluble protein and increase in MDA, H2O2, EL, proline, total carotenoid, ascorbic acid, polyphenols, flavonoids, and antioxidant activity. However, responses of these parameters were differential in respect to cultivars and the degree of drought stresses. No significant difference was observed in control and LDS for most of the traits. The cultivars VA14 and VA16 were identified as more tolerant to drought and could be used for further evaluations in future breeding programs and new cultivar release programs. Positively significant correlations among MDA, H2O2, compatible solutes, and non-enzymatic antioxidant (proline, TPC, TFC, and TAC) suggested that compatible solutes and non-enzymatic antioxidant played vital role in detoxifying of ROS in A. tricolor cultivar. The increased content of ascorbic acid indicated the crucial role of the ASC–GSH cycle for scavenging ROS in A. tricolor.

183 citations


Cites background from "Role of Secondary Metabolites and B..."

  • ...Plants have evolved both enzymatic and nonenzymatic defense systems for scavenging and detoxifying ROS, resulting in antioxidant defense capacity [3]....

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  • ...Total carotenoid is a lipophilic antioxidant and is able to detoxify various forms ROS [42]....

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  • ...Therefore, present investigations were aimed (i) to elucidate key mechanisms involved in drought tolerance by comparing selected A. tricolor cultivars, differing in their extent of drought tolerance; (ii) to identify tolerant cultivars to drought stress; and (iii) to explore the relationships among physiological, ROS markers, compatible solutes, and non-enzymatic antioxidant to obtain more tolerant cultivars under drought stress....

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  • ...Drought stress leads to the accumulation of reactive oxygen species (ROS), which might initiate destructive oxidative processes such as lipid peroxidation, chlorophyll and betalain bleaching, and protein oxidation....

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  • ...Among the various ROS, freely diffusible and relatively long-lived H2O2 acts as a central player in stress signal transduction pathways....

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References
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Journal ArticleDOI
TL;DR: The mechanisms of ROS generation and removal in plants during development and under biotic and abiotic stress conditions are described and the possible functions and mechanisms for ROS sensing and signaling in plants are compared with those in animals and yeast.
Abstract: Several reactive oxygen species (ROS) are continuously produced in plants as byproducts of aerobic metabolism. Depending on the nature of the ROS species, some are highly toxic and rapidly detoxified by various cellular enzymatic and nonenzymatic mechanisms. Whereas plants are surfeited with mechanisms to combat increased ROS levels during abiotic stress conditions, in other circumstances plants appear to purposefully generate ROS as signaling molecules to control various processes including pathogen defense, programmed cell death, and stomatal behavior. This review describes the mechanisms of ROS generation and removal in plants during development and under biotic and abiotic stress conditions. New insights into the complexity and roles that ROS play in plants have come from genetic analyses of ROS detoxifying and signaling mutants. Considering recent ROS-induced genome-wide expression analyses, the possible functions and mechanisms for ROS sensing and signaling in plants are compared with those in animals and yeast.

9,908 citations


"Role of Secondary Metabolites and B..." refers background in this paper

  • ...Very few plant responses are stress-specific and most of the stresses elicit generic responses like production of excessive reactive oxygen species (ROS) (Apel and Hirt 2004)....

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  • ...the stresses elicit generic responses like production of excessive reactive oxygen species (ROS) (Apel and Hirt 2004)....

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  • ...…University of Agriculture & Technology, Pantnagar, Uttarakhand, India 263145 e-mail: plantstress@gmail.com S. K. Guru Department of Plant Physiology, G. B. Pant University of Agriculture & Technology, Pantnagar, Uttarakhand, India 263145 productivity on a year-to-year basis (Apel and Hirt 2004)....

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  • ...productivity on a year-to-year basis (Apel and Hirt 2004)....

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Journal ArticleDOI
TL;DR: It is now possible to establish the antioxidant activities of plant-derived flavonoids in the aqueous and lipophilic phases, and to assess the extent to which the total antioxidant potentials of wine and tea can be accounted for by the activities of individual polyphenols.

4,076 citations

Journal ArticleDOI
TL;DR: Attention is drawn to the perception and signalling processes (chemical and hydraulic) of water deficits, which are essential for a holistic understanding of plant resistance to stress, which is needed to improve crop management and breeding techniques.
Abstract: In the last decade, our understanding of the processes underlying plant response to drought, at the molecular and whole-plant levels, has rapidly progressed. Here, we review that progress. We draw attention to the perception and signalling processes (chemical and hydraulic) of water deficits. Knowledge of these processes is essential for a holistic understanding of plant resistance to stress, which is needed to improve crop management and breeding techniques. Hundreds of genes that are induced under drought have been identified. A range of tools, from gene expression patterns to the use of transgenic plants, is being used to study the specific function of these genes and their role in plant acclimation or adaptation to water deficit. However, because plant responses to stress are complex, the functions of many of the genes are still unknown. Many of the traits that explain plant adaptation to drought - such as phenology, root size and depth, hydraulic conductivity and the storage of reserves - are those associated with plant development and structure, and are constitutive rather than stress induced. But a large part of plant resistance to drought is the ability to get rid of excess radiation, a concomitant stress under natural conditions. The nature of the mechanisms responsible for leaf photoprotection, especially those related to thermal dissipation, and oxidative stress are being actively researched. The new tools that operate at molecular, plant and ecosystem levels are revolutionising our understanding of plant response to drought, and our ability to monitor it. Techniques such as genome-wide tools, proteomics, stable isotopes and thermal or fluorescence imaging may allow the genotype-phenotype gap to be bridged, which is essential for faster progress in stress biology research.

3,287 citations

Journal ArticleDOI
TL;DR: The evidence supports at least a partial antioxidant role in vivo for many classes of plant metabolite, and many other compounds as potential antioxidants can be inferred by their similarity to synthetic antioxidants of related structure.

1,809 citations


"Role of Secondary Metabolites and B..." refers background in this paper

  • ...Such alkaloids appear to be strictly physical quenchers and are not destroyed chemically by the process of quenching (Larson 1988)....

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Journal ArticleDOI
TL;DR: The accumulation of red or purple flavonoids is a hallmark of plant stress and mounting evidence points to diverse physiological functions for these compounds in the stress response.

1,654 citations


"Role of Secondary Metabolites and B..." refers background in this paper

  • ...The induction of phenolic compound biosynthesis was reported in wheat in response to nickel toxicity and in maize in response to aluminium (Winkel-Shirley 2002)....

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  • ...The roots of many plants exposed to heavy metals exude high levels of phenolics (Winkel-Shirley 2002)....

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