期刊
PLANTS-BASEL
卷 10, 期 11, 页码 -出版社
MDPI
DOI: 10.3390/plants10112519
关键词
Sorghum bicolor L. moench; a-lipoic acid; salinity; transporter proteins and oxidative stress
资金
- Taif University, Taif, Saudi Arabia [TURSP-2020/307]
The study showed that foliar application of alpha-Lipoic acid (ALA) significantly promoted the growth of salt-stressed sorghum plants by improving plant growth, reducing oxidative damage, increasing antioxidant enzyme activity, decreasing sodium and Na/K ratio, and increasing potassium and calcium content. The molecular study confirmed the role of ALA in regulating K+/Na+ selectivity under saline conditions by downregulating SOS1 and NHX1 genes and upregulating HKT1 gene.
In plants, alpha-Lipoic acid (ALA) is considered a dithiol short-chain fatty acid with several strong antioxidative properties. To date, no data are conclusive regarding its effects as an exogenous application on salt stressed sorghum plants. In this study, we investigated the effect of 20 mu M ALA as a foliar application on salt-stressed sorghum plants (0, 75 and 150 mM as NaCl). Under saline conditions, the applied-ALA significantly (p & LE; 0.05) stimulated plant growth, indicated by improving both fresh and dry shoot weights. A similar trend was observed in the photosynthetic pigments, including Chl a, Chl b and carotenoids. This improvement was associated with an obvious increase in the membrane stability index (MSI). At the same time, an obvious decrease in the salt induced oxidative damages was seen when the concentration of H2O2 and malondialdehyde (MDA) was reduced in the salt stressed leaf tissues. Generally, ALA-treated plants demonstrated higher antioxidant enzyme activity than in the ALA-untreated plants. A moderate level of salinity (75 mM) induced the highest activities of superoxide dismutase (SOD), guaiacol peroxidase (G-POX), and ascorbate peroxidase (APX). Meanwhile, the highest activity of catalase (CAT) was seen with 150 mM NaCl. Interestingly, applied-ALA led to a substantial decrease in the concentration of both Na and the Na/K ratio. In contrast, K and Ca exhibited a considerable increase in this respect. The role of ALA in the regulation of K+/Na+ selectivity under saline condition was confirmed through a molecular study (RT-PCR). It was found that ALA treatment downregulated the relative gene expression of plasma membrane (SOS1) and vacuolar (NHX1) Na+/H+ antiporters. In contrast, the high-affinity potassium transporter protein (HKT1) was upregulated.
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