Gamma-aminobutyric acid (GABA) alleviates salt damage in tomato by modulating Na+ uptake, the GAD gene, amino acid synthesis and reactive oxygen species metabolism
Background: Salt stress is a serious abiotic stress that caused crop growth inhibition and yield decline. Previous studies have reported on the the synthesis of gamma-aminobutyric acid (GABA) and its relationship with plant resistance under various abiotic stress. However, the relationship between exogenous GABA alleviating plant salt stress damage and ion flux, amino acid synthesis, and key enzyme expression remains largely unclear. We investigated plant growth, Na+ transportation and accumulation, reactive oxygen species (ROS) metabolism and evaluated the effect of GABA on amino acids especially SlGADs gene expression and the endogenous GABA content of tomato (Solanum lycopersicum L.) seedlings treated with or without 5 mmol·L-1 GABA under 175 mmol·L-1 NaCl stress.
Results: Exogenous application of GABA significantly reduced the salt damage index and increased plant height, chlorophyll content and the dry and fresh weights of tomato plants exposed to NaCl stress. GABA significantly reduced Na+ accumulation in leaves and roots by preventing Na+ influx in roots and transportation to leaves. The transcriptional expression of SlGAD1-3 genes were induced by NaCl stress especially with GABA application. Among them, SlGAD1 expression was the most sensitive and contributed the most to the increase in glutamic acid decarboxylase (GAD) activity induced by NaCl and GABA application; Exogenous GABA increased GAD activity and amino acid contents in tomato leaves compared with the levels under NaCl stress alone, especially the levels of endogenous GABA, proline, glutamate and eight other amino acids. These results indicated that SlGADs transcriptional expression played an important role in tomato plant resistance to NaCl stress with GABA application by enhancing GAD activity and amino acid content. GABA significantly alleviated the active oxygen-related injury of leaves under NaCl stress by increasing the activities of antioxidant enzymes and decreasing the contents of active oxygen species and malondialdehyde.
Conclusion: Exogenous GABA had a positive effect on the resistance of tomato seedlings to salt stress, which was closely associated with reducing Na+ flux from root to leaves, increasing amino acid content and strengthening antioxidant metabolism. Endogenous GABA content was induced by salt and exogenous GABA at both the transcriptional and metabolic levels.
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Alignment of conserved region amino acid sequence of four tomato GAD genes. Note: Identical and similar base are shown in black, pink or green, respectively.
Posted 20 Aug, 2020
On 09 Oct, 2020
On 23 Sep, 2020
Received 17 Sep, 2020
On 23 Aug, 2020
Received 19 Aug, 2020
Invitations sent on 18 Aug, 2020
On 18 Aug, 2020
On 17 Aug, 2020
On 16 Aug, 2020
On 16 Aug, 2020
Received 18 Jul, 2020
On 18 Jul, 2020
Received 16 Jul, 2020
On 04 Jul, 2020
Invitations sent on 29 Jun, 2020
On 29 Jun, 2020
On 17 Jun, 2020
On 16 Jun, 2020
On 16 Jun, 2020
On 15 Jun, 2020
Gamma-aminobutyric acid (GABA) alleviates salt damage in tomato by modulating Na+ uptake, the GAD gene, amino acid synthesis and reactive oxygen species metabolism
Posted 20 Aug, 2020
On 09 Oct, 2020
On 23 Sep, 2020
Received 17 Sep, 2020
On 23 Aug, 2020
Received 19 Aug, 2020
Invitations sent on 18 Aug, 2020
On 18 Aug, 2020
On 17 Aug, 2020
On 16 Aug, 2020
On 16 Aug, 2020
Received 18 Jul, 2020
On 18 Jul, 2020
Received 16 Jul, 2020
On 04 Jul, 2020
Invitations sent on 29 Jun, 2020
On 29 Jun, 2020
On 17 Jun, 2020
On 16 Jun, 2020
On 16 Jun, 2020
On 15 Jun, 2020
Background: Salt stress is a serious abiotic stress that caused crop growth inhibition and yield decline. Previous studies have reported on the the synthesis of gamma-aminobutyric acid (GABA) and its relationship with plant resistance under various abiotic stress. However, the relationship between exogenous GABA alleviating plant salt stress damage and ion flux, amino acid synthesis, and key enzyme expression remains largely unclear. We investigated plant growth, Na+ transportation and accumulation, reactive oxygen species (ROS) metabolism and evaluated the effect of GABA on amino acids especially SlGADs gene expression and the endogenous GABA content of tomato (Solanum lycopersicum L.) seedlings treated with or without 5 mmol·L-1 GABA under 175 mmol·L-1 NaCl stress.
Results: Exogenous application of GABA significantly reduced the salt damage index and increased plant height, chlorophyll content and the dry and fresh weights of tomato plants exposed to NaCl stress. GABA significantly reduced Na+ accumulation in leaves and roots by preventing Na+ influx in roots and transportation to leaves. The transcriptional expression of SlGAD1-3 genes were induced by NaCl stress especially with GABA application. Among them, SlGAD1 expression was the most sensitive and contributed the most to the increase in glutamic acid decarboxylase (GAD) activity induced by NaCl and GABA application; Exogenous GABA increased GAD activity and amino acid contents in tomato leaves compared with the levels under NaCl stress alone, especially the levels of endogenous GABA, proline, glutamate and eight other amino acids. These results indicated that SlGADs transcriptional expression played an important role in tomato plant resistance to NaCl stress with GABA application by enhancing GAD activity and amino acid content. GABA significantly alleviated the active oxygen-related injury of leaves under NaCl stress by increasing the activities of antioxidant enzymes and decreasing the contents of active oxygen species and malondialdehyde.
Conclusion: Exogenous GABA had a positive effect on the resistance of tomato seedlings to salt stress, which was closely associated with reducing Na+ flux from root to leaves, increasing amino acid content and strengthening antioxidant metabolism. Endogenous GABA content was induced by salt and exogenous GABA at both the transcriptional and metabolic levels.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
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Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14