GABA-Alleviated Oxidative Injury Induced by Salinity, Osmotic Stress and their Combination by Regulating Cellular and Molecular Signals in Rice

Abstract

This study was conducted in order to determine the effect of priming with γ-aminobutyric acid (GABA) at 0.5 mM on rice (Oryza sativa L.) seed germination under osmotic stress (OS) induced by polyethylene glycol (30 g/L PEG 6000); and salinity stress (S, 150 mM NaCl) and their combination (OS+S). Priming with GABA significantly alleviated the detrimental effects of OS, S and OS+S on seed germination and seedling growth. The photosynthetic system and water relation parameters were improved by GABA under stress. Priming treatment significantly increased the GABA content, sugars, protein, starch and glutathione reductase. GABA priming significantly reduced Na+ concentrations, proline, free radical and malonaldehyde and also significantly increased K+ concentration under the stress condition. Additionally, the activities of antioxidant enzymes, phenolic metabolism-related enzymes, detoxification-related enzymes and their transcription levels were improved by GABA priming under stress. In the GABA primed-plants, salinity stress alone resulted in an obvious increase in the expression level of Calcineurin B-like Protein-interacting protein Kinases (CIPKs) genes such as OsCIPK01, OsCIPK03, OsCIPK08 and OsCIPK15, and osmotic stress alone resulted in obvious increase in the expression of OsCIPK02, OsCIPK07 and OsCIPK09; and OS+S resulted in a significant up-regulation of OsCIPK12 and OsCIPK17. The results showed that salinity, osmotic stresses and their combination induced changes in cell ultra-morphology and cell cycle progression resulting in prolonged cell cycle development duration and inhibitory effects on rice seedlings growth. Hence, our findings suggested that the high tolerance to OS+S is closely associated with the capability of GABA priming to control the reactive oxygen species (ROS) level by inducing antioxidant enzymes, secondary metabolism and their transcription level. This knowledge provides new evidence for better understanding molecular mechanisms of GABA-regulating salinity and osmotic-combined stress tolerance during rice seed germination and development.

The Integration of Bio and Organic Fertilizers Improve Plant Growth, Grain Yield, Quality and Metabolism of Hybrid Maize (Zea mays L.)

“…Seed priming has been frequently used to improve seed germination and seedling development and can also improve plant growth in a wide range of environmental conditions [30][31][32][33][34][35]. As a priming agent, humic acid (HA) are usually used as a kind of hormone that promotes plant growth rather than improving the chemical or the physical conditions of the soil.…”

The Halotolerant Rhizobacterium—Pseudomonas koreensis MU2 Enhances Inorganic Silicon and Phosphorus Use Efficiency and Augments Salt Stress Tolerance in Soybean (Glycine max L.)

“…The world population is estimated to reach 9 billion by 2050 and approximately 800 million hectares of cultivable lands in the earth have high salt concentration [ 2 ]. Salt stress has adverse effects on plant metabolism, which include osmotic stress, ionic imbalance, oxidative damage, reduced water acquisition, damage of cellular structures, and declination in gas exchange rates, which ultimately leads to plant death [ 3 , 4 ].…”

γ-Aminobutyric Acid Participates in the Adult-Phase Adventitious Rooting Recalcitrance

“…Exogenous GABA imparts salt tolerance by increasing proline and soluble sugar contents and upregulating antioxidants in maize (Zea mays) (Wang et al 2017). GABA priming in rice germinating seeds significantly alleviates the effects of osmotic and salinity stress on seed germination and seedling growth, by inducing antioxidant activities (Sheteiwy et al 2019). In addition, GABA application was shown to promote the growth of maize or muskmelon (Cucumis melo) under abiotic stress by reducing the production of reactive oxygen species (ROS), activating antioxidant activity, and improving photosynthesis (Salah et al 2019;Jin et al 2019).…”