γ-Aminobutyric Acid Imparts Partial Protection from Salt Stress Injury to Maize Seedlings by Improving Photosynthesis and Upregulating Osmoprotectants and Antioxidants

Abstract

γ-Aminobutyric acid (GABA) has high physiological activity in plant stress physiology. This study showed that the application of exogenous GABA by root drenching to moderately (MS, 150 mM salt concentration) and severely salt-stressed (SS, 300 mM salt concentration) plants significantly increased endogenous GABA concentration and improved maize seedling growth but decreased glutamate decarboxylase (GAD) activity compared with non-treated ones. Exogenous GABA alleviated damage to membranes, increased in proline and soluble sugar content in leaves, and reduced water loss. After the application of GABA, maize seedling leaves suffered less oxidative damage in terms of superoxide anion (O2·−) and malondialdehyde (MDA) content. GABA-treated MS and SS maize seedlings showed increased enzymatic antioxidant activity compared with that of untreated controls, and GABA-treated MS maize seedlings had a greater increase in enzymatic antioxidant activity than SS maize seedlings. Salt stress severely damaged cell function and inhibited photosynthesis, especially in SS maize seedlings. Exogenous GABA application could reduce the accumulation of harmful substances, help maintain cell morphology, and improve the function of cells during salt stress. These effects could reduce the damage to the photosynthetic system from salt stress and improve photosynthesis and chlorophyll fluorescence parameters. GABA enhanced the salt tolerance of maize seedlings.

Research on the adaptive mechanism of photosynthetic apparatus under salt stress: New directions to increase crop yield in saline soils

“…In recent decades, exogenous protectants, such as osmoprotectants (mannitol) (Chan, Grumet, & Loescher, ; C. Ma, Ren, Hu, Chen, & Li, ), phytohormones (Brassinosteroids, ABA) (S. Gao, Sun, Li, Shi, & Qi, ; Talaat & Shawky, ; Yue, Zhang, You, Wang, & Zhang, ), signalling molecules (hydrogen sulphide, nitric oxide, γ‐aminobutyric acid) (Deng et al, ; Dong, Jinc, Liu, Xu, & Kong, ; Khoshbakht, Asghari, & Haghighi, ; Y. Wang, Gu, et al, ), polyamines (Spd, Spm, Put) (Khoshbakht, Asghari, & Haghighi, ; Shu et al, ; Yaakoubi, Hamdani, Bekalé, & Carpentier, ), microorganisms (arbuscular mycorrhizal fungi, Bacillus subtilis ) (Han et al, ; Y. Zhang, Gao, Guo, & Hao, ), trace elements (Ca, Si, Se) (Diao et al, ; G. Wang, Bi, et al, ; G. Zhao, Li, Xing, Wang, & Chang, ) and other substances (5‐azacytidine) (Zhong, Xu, & Wang, ) have been found effective in mitigating salt‐induced damages. However, different exogenous substances may be used to enhance plant resistance, but excessive exogenous substances may adversely affect plants.…”

Oversensitivity of Arabidopsis gad1/2 mutant to NaCl treatment reveals the importance of GABA in salt stress responses

“…Furthermore, high GABA accumulating Arabidopsis pop2 mutants showed tolerance to mannitol induced osmotic stress (Renault et al, 2010). Similarly, exogenous application of GABA to maize seedlings increased the endogenous GABA level and subsequently improved tolerance to salt stress (Wang et al, 2017). Sensitivity to the ionic component of salt stress requires the accumulation of Na + to a toxic level.…”

A metabolomic strategy revealed the role of JA and SA balance in Clematis terniflora DC. Response to UVB radiation and dark

“…In a study of nitrogen metabolism under nitrate‐limited and dark conditions, Glu, Gln, Asp, Asn and Pro coincidently restored nitrogen content to wild‐type levels in a T‐DNA insertion mutant of Arabidopsis plastidial folylpolyglutamate synthetase gene (Meng et al ). The high Pro content in transgenic tobacco was also suggested to be attributable to excess Gln production (Wang et al , ). These results indicate that SA functions in nitrogen metabolism by enhancing metabolic flux from Glu, Gln and Asp to Pro, which results in an increased tolerance to oxidative stress by the accumulation of Pro in C. terniflora in response to HUVB + D.…”

“…In a study of nitrogen metabolism under nitrate-limited and dark conditions, Glu, Gln, Asp, Asn and Pro coincidently restored nitrogen content to wild-type levels in a T-DNA insertion mutant of Arabidopsis plastidial folylpolyglutamate synthetase gene (Meng et al 2017). The high Pro content in transgenic tobacco was also suggested to be attributable to excess Gln production (Wang et al 2017a(Wang et al , 2017b.…”

“…5B). GABA, a non-protein amino acid, plays an important protective role in plant stress resistance (Wang et al 2017a(Wang et al , 2017b. The GABA shunt pathway, which modulates the balance of the carbon-nitrogen ratio in plants, plays a major role in primary carbon metabolism (Fait et al 2008) and is functionally linked with the tricarboxylic acid cycle (TCA) (Studart-Guimarães et al 2007).…”