Contribution of Gamma amino butyric acid (GABA) to salt stress responses of Nicotiana sylvestris CMSII mutant and wild type plants (original) (raw)
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The Role of the γ-Aminobutyric Acid (GABA) in Plant Salt Stress Tolerance
Horticulturae
γ-Aminobutyric acid (GABA) is a non-protein amino acid that accumulates in many plant species in response to environmental stress. A number of reverse-genetic experiments and omics analyses have revealed positive relationships between GABA levels and tolerance to stresses. Furthermore, the application of exogenous GABA has been demonstrated to effectively reduce ROS levels, enhance membrane stability and modulate phytohormones cross-talk, thus improving tolerance against multiple stresses. However, molecular mechanisms regulating GABA homeostasis and physiological functions in plants remain largely unclear. In this review, we focus on the recent achievements in deciphering the role of genetic manipulations to modulate endogenous GABA levels and the exogenous application of GABA and associated metabolites to improve tolerance to salt stress. Finally, we discuss the role of GABA in the regulation of ion homeostasis in high-salinity conditions. These findings have laid the groundwork f...
Plant & cell physiology, 2015
NAD-dependent glutamate dehydrogenase (NAD-GDH) of higher plants has a central position at the interface between carbon and nitrogen metabolism due to its ability to carry out the deamination of glutamate. In order to obtain a better understanding of the physiological function of NAD-GDH under salt stress conditions, transgenic tobacco (Nicotiana tabacum L.) plants that overexpress two genes from Nicotiana plumbaginifolia individually (GDHA and GDHB) or simultaneously (GDHA/B) were grown in the presence of 50 mM NaCl. In the different GDH overexpressors, the NaCl treatment induced an additional increase in GDH enzyme activity, indicating that a post-transcriptional mechanism regulates the final enzyme activity under salt stress conditions. A greater shoot and root biomass production was observed in the three types of GDH overexpressors following growth in 50 mM NaCl, when compared with the untransformed plants subjected to the same salinity stress. Changes in metabolites representat...
The Arabidopsis pop2-1mutant reveals the involvement of GABA transaminase in salt stress tolerance
BMC Plant Biology, 2010
Background GABA (γ-aminobutyric acid) is a non protein amino acid that has been reported to accumulate in a number of plant species when subjected to high salinity and many other environmental constraints. However, no experimental data are to date available on the molecular function of GABA and the involvement of its metabolism in salt stress tolerance in higher plants. Here, we investigated the regulation of GABA metabolism in Arabidopsis thaliana at the metabolite, enzymatic activity and gene transcription levels upon NaCl stress. Results We identified the GABA transaminase (GABA-T), the first step of GABA catabolism, as the most responsive to NaCl. We further performed a functional analysis of the corresponding gene POP2 and demonstrated that the previously isolated loss-of-function pop2-1 mutant was oversensitive to ionic stress but not to osmotic stress suggesting a specific role in salt tolerance. NaCl oversensitivity was not associated with overaccumulation of Na+ and Cl- but...
Physiological and Biochemical Responses of Plants to Salt Stress
2015
Salinity affects plant growth and development in various ways through its impact on photosynthesis, water relations and nutrient absorption. Additionally, the biochemical composition of plants is also affected by salinity through changes in the concentration and type of proteins, amino acids, sugars and other carbohydrates. This paper elucidates with examples the changes that occur in the plant‟s physiological functions and biochemical composition as a result of increased salinity of the plant‟s environment. It is highlighted that the fundamental mechanism of salinity‟s effects on plant function is the increase in the osmotic pressure of the plant‟s environment that inhibits the absorption of water and nutrients. Invariably, salinity inhibits photosynthesis through its effects on stomatal conductance, water and nutrient uptake and decrease in the chlorophyll concentration. Subsequently, higher levels of salinity create an excessive accumulation of salts in plant tissues that causes ...
Plants
Gac is a carotenoid-rich, healthful tropical fruit; however, its productivity is limited by soil salinity, a growing environmental stress. This study aimed to evaluate the effects of salinity stress on key physiological traits and metabolites in 30-day-old gac seedling leaves, treated with 0, 25-, 50-, 100-, and 150-mM sodium chloride (NaCl) for four weeks to identify potential alarm, acclimatory, and exhaustion responses. Electrolyte leakage increased with increasing NaCl concentrations (p < 0.05) indicating loss of membrane permeability and conditions that lead to reactive oxygen species production. At 25 and 50 mM NaCl, superoxide dismutase (SOD) activity, starch content, and total soluble sugar increased. Chlorophyll a, and total chlorophyll increased at 25 mM NaCl but decreased at higher NaCl concentrations indicating salinity-induced thylakoid membrane degradation and chlorophyllase activity. Catalase (CAT) activity decreased (p < 0.05) at all NaCl treatments, while asco...
Acta Biologica Colombiana, 2013
A possible survival strategy for plants under saline conditions is to use some compounds that could alleviate the salt stress effect. One of these compounds is nicotinamide (vitamin B3/niacin). The effect of exogenous application of nicotinamide with different concentrations (0, 200 or 400 mg l-1) on faba bean (Vicia faba L.) plant grown at different NaCl levels (0, 50 or 100 mM) was investigated in the wire house of the National Research Centre, Cairo, Egypt. Salinity stress significantly reduced the photosynthetic pigments, polysaccharides, total carbohydrates, total-N contents of shoot, plant height, leaves number, fresh and dry weights of shoot, seed yield, total carbohydrates and total crude protein of the yielded seeds compared with those of the control plants. In contrast, salinity induced marked increases in sucrose, total soluble sugars, total free amino acids, proline, lipid peroxidation product (MDA) and some oxidative enzymes (polyphenol-oxidase and peroxidase). Also, salinity stress increased Na + contents with the decreases of other macro and micro elements contents (P, K + , Mg 2+ , Ca 2+ , Fe 2+ , Mn 2+ , Zn 2+ and Cu 2+) of shoots and the yielded seeds of faba bean. Foliar spraying of nicotinamide alleviated the adverse effects of salinity stress through increased the photosynthetic pigments, polysaccharides, total carbohydrates, total N concentration of shoot, plant height, leaves number, fresh and dry weights of shoot, and seed yield as well as, sucrose, total soluble sugars, total free amino acids and proline, compared with those of the corresponding salinity levels, while decreased lipid peroxidation product as malondialdehyde (MDA) and the oxidative enzymes (polyphenol oxidase and peroxidase enzymes). Nicotinamide inhibited the uptake of Na + and accelerated the accumulation of P, K + , Mg 2+ , Ca 2+ , Fe 2+ , Mn 2+ , Zn 2+ and Cu 2+ concentrations in the shoots of salt stressed plants and enhanced total carbohydrate and total crude protein percentage and solutes concentrations in seeds of salinity treated plants. Nicotinamide, not only neutralized the effect of salinity stress but resulted in a significant improvement in physiological and biochemical parameters as well as the concentrations of soluble sugars, proline, amino acids, and total N and other mineral contents.
Plant Physiology and Biochemistry, 2020
Freshly separated cyanobionts of Azolla microphylla and Azolla caroliniana plants exposed to salinity showed decline in the cellular constituents such as chlorophyll (23.1 and 38.9%) and protein (12.9 and 19.3%). However, an increase in the carotenoid and sugar content was observed. Exposure to salinity stress reduced the heterocyst frequency (35.4 and 57.2%) and nitrogenase activity (37.7 and 46.3%) of the cyanobionts. Increase in the activity of antioxidant enzymes such as super oxide dismutase (50.6 and 11.5%), ascorbate peroxidase (63.7 and 57.9%), catalase (94.2 and 22.5%) as well as non-enzymatic antioxidant proline (18.8 and 13.3%) was also observed in response to salinity. The cyanobionts exhibited significant increase in the intracellular Na þ level and reduced intracellular K þ /Na þ and Ca 2þ /Na þ ratio in response to salinity. The results demonstrate the adverse impact of salinity on the freshly separated cyanobionts as similar to free living cyanobacteria. These results may be helpful in the critical evaluation of salinity tolerance mechanism of the cyanobiont and its interaction with the host.
Factors Influencing the Salt Stress Tolerance in Plants – An Overview
Salinity stress is one of the adverse stresses among abiotic stress which mitigates ion toxicity, water unavailability and oxidative stress apart from the hampering growth and productivity of plants. Various anthropogenic activities also indulge in limiting the cultivatable land thus minimizing the food productivity. For sustainable food supply to world population which is increasing at its peril, it is important to develop stress tolerant crops. Salt adaptation involves various trait of gene which comes across in an integrated manner to lessen the adverse effect of salt. This salt signaling cascade activates various mechanisms after perceiving the signal at membrane level receptor which leads to activate the various genes and transcription factors involved in production of osmolytes and ion sequestration. In this review we tried to accentuate the impacts of salinity on plant, role of calcium ion, transcription factor, osmolytes and plant hormone in salt tolerance.
Molecular Plant, 2013
Plants employ several strategies to maintain cellular ion homeostasis under salinity stress, including mediating ion fluxes by transmembrane transport proteins and adjusting osmotic pressure by accumulating osmolytes. The HKT (high-affinity potassium transporter) gene family comprises Na + and Na + /K + transporters in diverse plant species, with HKT1;1 as the only member in Arabidopsis thaliana. Cell-type-specific overexpression of AtHKT1;1 has been shown to prevent shoot Na + overaccumulation under salinity stress. Here, we analyzed a broad range of metabolites and elements in shoots and roots of different AtHKT1;1 genotypes and their parental strains before and after salinity stress, revealing a reciprocal relationship of metabolite differences between an AtHKT1;1 knockout line (hkt1;1) and the AtHKT1;1 overexpressing lines (E2586 UASGAL4:HKT1;1 and J2731*UASGAL4:HKT1;1). Although levels of root sugars were increased after salt stress in both AtHKT1;1 overexpressing lines, E2586 UASGAL4:HKT1;1 showed higher accumulation of the osmoprotectants trehalose, gentiobiose, and melibiose, whereas J2731*UASGAL4:HKT1;1 showed higher levels of sucrose and raffinose, compared with their parental lines, respectively. In contrast, the knockout line hkt1;1 showed strong increases in the levels of the tricarboxylic acid (TCA) cycle intermediates in the shoots after salt treatment. This coincided with a significant depletion of sugars, suggesting that there is an increased rate of carbon influx into the TCA cycle at a constant rate of C-efflux from the cycle, which might be needed to support plant survival during salt stress. Using correlation analysis, we identified associations between the Na + content and several sugars, suggesting that regulation of sugar metabolism is important in plant responses to salinity stress.