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The effect of NaCl on GABA content (a), GAD activity (b), and GABA-T activity (c) of barley seedlings. Barley seedings were cultured under CK and N treatments, respectively. Sampling was performed on day 0, 2, 4, and 6, respectively. Bars represent standard deviation of means (n = 3), and means with different lower case letters were significantly different (p < 0.05). Two-way ANOVA was used.
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It has been revealed that high NaCl stress (>60 mmol L−1) induced phenolics accumulation in barley seedlings, with γ-aminobutyric acid (GABA) playing a key role. Interestingly, low NaCl stimulus (20 mmol L−1) enhancing phenolics synthesis and growth of barley seedlings was also reported recently. Hence, exogenous GABA and its bio-synthesis inhibito...
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Context 1
... content (a), GAD (b), and GABA-T (c) activity of barley seedlings treated with 20 mM NaCl are shown in Figure 1. It can be seen that the GABA content of barley seedlings increased to its maximum on the 2nd day, which was 1.25 times that of the control. ...
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... can be seen that the GABA content of barley seedlings increased to its maximum on the 2nd day, which was 1.25 times that of the control. GABA content gradually decreased with the increase of germination days under N treatment, which always higher than the control (Figure 1a). ...
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... results show that there was a downward trend in the GAD activity of barley seedlings with the increase of germination days (Figure 1b). Among them, GAD activity under N treatment was significantly increased by 14.84% and 36.59% ...
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... this study showed that low NaCl concentration (20 mmol L −1 ) did not inhibit the growth of barley seedlings, but promoted the growth status (Figure 2). Simultaneously, the endogenous GABA level significantly increased (Figure 1a), due to a higher level of GAD activity compared with CK (Figure 1b). GABA, as a signal molecule, has been widely studied in plant stress signal transmission [2]. ...
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... this study showed that low NaCl concentration (20 mmol L −1 ) did not inhibit the growth of barley seedlings, but promoted the growth status (Figure 2). Simultaneously, the endogenous GABA level significantly increased (Figure 1a), due to a higher level of GAD activity compared with CK (Figure 1b). GABA, as a signal molecule, has been widely studied in plant stress signal transmission [2]. ...
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... low concentrations of NaCl promoted the growth and biomass accumulation of barley seedlings in the present study, MDA content and electrical leakage also increased significantly (Figure 2d), indicating that low concentration of NaCl also slightly caused damage to the tissue and cells of seedlings. Simultaneously, the synthesis of endogenous GABA was also activated (Figure 1), and GABA participated in phenolics synthesis of barley seedlings stimulated by low concentration of NaCl (20 mmol L −1 ). ...
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This study aimed to determine individual phenolic compounds of common produced Turkish raisins. As material, Sultan 7, Antep Karasi and Razaki raisins were used. The HPLC method was performed for the analysis of 11 phenolic compounds. The major phenolic acid was trans-caftaric acid and the major flavan-3-ol was also (+)-catechin. The trans-caftaric...
Citations
... Barley is not only rich in protein, dietary fiber, minerals, and other nutrients but also contains phenolic acid, glutathione, ascorbic acid, and other functional nutrients that promote human health. 1 Among these, the greatest concern are phenolic acids. Phenolic acids are secondary metabolites synthesized by the phenylpropane pathway in plants, and their synthesis involves many enzymes, including phenylalanine aminolase (PAL), 4-coumaric acid-coenzyme A (4CL), cinnamic acid-3-hydroxylase (C3H), cinnamic acid-4-hydroxylase (C4H), and so on. ...
BACKGROUND
Phenolic acid exhibits a variety of well‐known physiological functions. In this study, optimal germination conditions to ensure total phenolic acid enrichment in barley sprouts induced by salicylic acid treatment and its effects on sprout physiology and activity, as well as the gene expression of key enzymes for phenolic acid biosynthesis, were investigated.
RESULTS
When sprouts were treated with 1 mmol L⁻¹ salicylic acid during germination and germinated at 25 °C for 4 days, the phenolic acid content was 1.82 times that of the control, reaching 1221.54 μg g⁻¹ fresh weight. Salicylic acid significantly increased the activity of phenylalanine aminolase and cinnamic acid‐4‐hydroxylase and the gene expression of phenylalanine aminolase, cinnamic acid‐3‐hydroxylase, cinnamic acid‐4‐hydroxylase, 4‐coumaric acid‐coenzyme A, caffeic acid O‐methyltransferase, and ferulate‐5‐hydroxylase in barley sprouts. However, salicylic acid treatment significantly increased malondialdehyde and H2O2 content, H2O2 and O2⁻ fluorescence intensity, as well as significantly decreasing sprout length and fresh weight. Salicylic acid treatment markedly increased the activity of peroxidase and catalase and the gene expression of peroxidase, catalase, and ascorbate peroxidase in barley sprouts.
CONCLUSION
Salicylic acid treatment during barley germination significantly promoted the enrichment of total phenolic acid by increasing the activities and gene expression levels of enzymes involved in the phenolic acid biosynthesis pathway. Salicylic acid induced the accumulation of reactive oxygen species, inhibited sprout growth, and activated the antioxidant system. This study provides a basis for the future development of functional foods using phenol acid‐rich plants as raw materials. © 2024 Society of Chemical Industry.
... Other researchers have obtained similar results to those of this research. Under NaCl stress, GABA levels in Barclay seedings, soybean sprouts, sugar beet, and poplar also increased (Behr et al. 2021;Ji et al. 2020;Wang et al. 2021;. In plants, GABA can act as a signal molecule to promote plant growth and alleviate abiotic stress. ...
Planting economic crops in soil with salt imbalances can improve land use efficiency. Hemp, which can be planted in low-salinity soil, is a crop with a very high economic value. To reveal the salt tolerance mechanism of hemp, the leaves of Longma #3 and #9 were collected at 0, 2, 4, and 6 days after salt stress in this study, and transcriptome and metabolome joint analysis were performed. The concentration of glutamic acid, succinic acid and gamma-aminobutyric acid (GABA) was 12 times that of the control group. The large increase in succinic acid led to the maintenance of peroxidase and superoxide dismutase levels at normal values and a decrease in H2O2 and catalase. The enriched KEGG pathway citrate cycle (TCA cycle) contains the metabolic regulation of succinic acid. Succinic acid was positively correlated with the MAPK gene. The MAPK pathway is a key pathway of plant tolerance in a high-salt environment. This study provides a reference for research on NaCl tolerance in plants and can also provide an important reference for the cultivation of NaCl-tolerant hemp varieties.
... Furthermore, the application of 3-MP (3-mercaptopropionic acid), the GABA biosynthesis inhibitor, reversed those beneficial effects (but increased PAL, C4H, and 4CL protein levels). These results suggest that low-level NaCl stress promotes plant growth and phenolic synthesis through stimulated endogenous GABA metabolism, which, subsequently, affects other key metabolic pathways in barley seedlings [61]. ...
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 for future studies to explore the genetic, physiological , and molecular mechanisms of GABA-mediated improvements in plant productivity under high-salt environmental conditions.
... So salt stress caused by NaCl application was strongly reported to stimulate GAD activity in maize (Wang et al., 2017) and thus accumulate GABA in plants as an adaptive response to the stress condition. Recently, Wang et al. (2021) found that low concentration of NaCl could stimulate the endogenous GABA synthesis and regulate GABA metabolism during the germination of barley. ...
This study aimed to estimate the γ‐aminobutyric acid (GABA) content and glutamate decarboxylase activity (GAD) in germinated sorghum grain as affected by different concentrations of NaCl, pyridoxal 5‐phosphate (PLP), and CaCl2. In general, the obtained results revealed that the addition of low doses of NaCl (40 mmol/L), PLP (90 mmol/L), and CaCl2 (0.5 mmol/L) to the germination culture significantly (p < .05) enhanced the GABA content and subsequently improved the GAD activity in sorghum grains. Moreover, CaCl2 played a dominant role in the extent of enzymolysis, followed by NaCl and PLP. Regarding the GABA content, the optimal concentration of the NaCl, PLP, and CaCl2 was estimated as 41.07 mmol/L, 82.62 μmol/L, and 0.40 mmol/L, respectively. Under this optimal culture medium, the maximum GABA content was 0.336 mg/g. In conclusion, the findings of this work would provide a scientific basis for the industrialized production of GABA‐enriched sorghum foods. Different concentrations of NaCl, PLP, and CaCl2 were added to germination media. The GAD activity and GABA content of germinating sorghum grains were investigated. The addition of low doses of salt improves GAD activity and GABA content in sorghum grains.
Salinity stress is one of the major abiotic factors limiting sustainable agriculture. Halotolerant plant growth‐promoting bacteria (PGPB) increased salt stress tolerance in plants, but the mechanisms underlying the tolerance are poorly understood. This study investigated the PGP activity of four halotolerant bacteria under salinity stress and the tomato salt‐tolerance mechanisms induced by the synergy of these bacteria with the exopolysaccharide (EPS) mauran. All PGPB tested in this study were able to offer a significant improvement of tomato plant biomass under salinity stress; Peribacillus castrilensis N3 being the most efficient one. Tomato plants treated with N3 and the EPS mauran showed greater tolerance to NaCl than the treatment in the absence of EPS and PGPB. The synergy of N3 with mauran confers salt stress tolerance in tomato plants by increasing sodium transporter genes' expression and osmoprotectant content, including soluble sugars, polyols, proline, GABA, phenols and the polyamine putrescine. These osmolytes together with the induction of sodium transporter genes increase the osmotic adjustment capacity to resist water loss and maintain ionic homeostasis. These findings suggest that the synergy of the halotolerant bacterium N3 and the EPS mauran could enhance tomato plant growth by mitigating salt stress and could have great potential as an inductor of salinity tolerance in the agriculture sector.
γ-aminobutyric acid (GABA), a non-protein amino acid, plays an important role in the human nervous system. GABA has revealed numerous physiological benefits in the medical and pharmaceutical fields in humans. It is regarded as an edible alternative treatment for the prevention and treatment of many diseases. As a result, GABA-rich functional foods are highly favored by consumers. Therefore, in order to meet the demand for healthy food, the use of effective and safe enrichment methods to increase the content of GABA in food has received much attention. The content of GABA in natural foods, bioenrichment techniques, and the health benefits of GABA-rich foods are discussed. In addition, this paper also discusses the shortcomings and future challenges of GABA bioconcentration technology, in order to provide a new idea for the investigation of GABA enrichment technology.
Isoflavones are a class of flavonoids that belong to a large family of polyphenols and synthesized predominantly in legume, and they play important roles including acting as antioxidant, preventing osteoporosis, reducing the risk of atherosclerosis, and protecting against cardiovascular disease. This study focused on the accumulation and synthetic metabolism of isoflavone in soybean hypocotyl and cotyledon calluses under UV-B radiation. The results showed that UV-B radiation significantly up-regulated the gene expression of phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), chalcone ketone synthase (CHS), chalcone isomerase (CHI), and isoflavone synthase (IFS), and enhanced their activity in soybean hypocotyl and cotyledon calluses. As a result, isoflavones content increased by 21.23 and 21.75% in soybean hypocotyl and cotyledon calluses, respectively. Among the isoflavones produced, malonyldaidzin was the dominant one in hypocotyl callus, while malonylglycitin and daidzein were the main isoflavones in cotyledon calluses. This study revealed that UV-B radiation induced isoflavone accumulation in soybean calluses, which could be an efficient strategy to improve the nutritional value of food and produce high levels of bioactive secondary metabolites.
Gamma-aminobutyric acid (GABA), a non-protein amino acid, possesses various health benefits and plays a signaling and defensive role in plants. Due to the low content of GABA in plant foods, scientists have made great efforts to enrich GABA in foods using various chemical, physical, and biological methods, including anaerobic treatment, cold, salt treatment, germination, microbial fermentation, crossbreeding, and innovative technologies such as ultrasound, ultraviolet, high pressure, etc. To effectively increase GABA in different foods, it is crucial to understand the underlying mechanisms and the virtues and limitations of different enrichment methods that are suitable for different foods. In this paper, we aimed to comprehensively review the recent progress on both conventional and innovative enrichment methods, the advantages and disadvantages, the associated mechanisms, and the applicable foods of these methods. We also summarized the functions of GABA in plants and microorganisms, the factors influencing GABA enrichment, the patents related to GABA enrichment, and the functional foods rich in GABA. The mechanisms of GABA enrichment mainly include modification of cell microstructure; influencing H⁺ and Ca²⁺ concentration and enzyme configuration, thereby activating glutamate decarboxylase; and regulation of gene and protein expression of enzymes involved in GABA biosynthesis and metabolism. This review will provide significant information on the production of GABA-enriched foods.
