Implication of Nitric Oxide Under Salinity Stress: The Possible Interaction with Other Signaling Molecules

Journal of Plant Growth Regulation - It is a well-established fact that nitric oxide (NO) is a multifaceted signaling molecule, which plays diverse role in organisms. In the past two decades,...     

GABA Requires Nitric Oxide for Alleviating Arsenate Stress in Tomato and Brinjal Seedlings

In recent years, gamma-aminobutyric acid (GABA) and nitric oxide (NO) have drawn much attention in reducing/alleviating metal toxicity in plants. Arsenic is a potentially toxic metal that imposes severe toxic effects on crop plants. Therefore, the present study was an attempt to explore the role of GABA and NO in the amelioration of arsenate As(V) toxicity in tomato and brinjal seedlings. Arsenate toxicity reduced fresh mass about by 17% in tomato and 25% in brinjal seedlings, increased the level of reactive oxygen species, antioxidant enzymes (except glutathione-S-transferase), and altered photosynthesis. However, exogenously applied GABA and sodium nitroprusside (SNP, a NO donor) improved the growth of both vegetables and reduced As(V) toxicity. Interestingly, As(V) toxicity was further increased on applying biosynthetic inhibitor of NO even in the presence of GABA, and under similar conditions addition of NO donor rescued the negative effect of biosynthetic inhibitor (L-NAME) of NO. This indicates that NO is crucial in GABA-mediated alleviation of As(V) toxicity in tomato and brinjal seedlings. Besides this, results revealed that c-PTIO (a NO scavenger) addition reversed the alleviatory effect of SNP also suggesting that NO is important in curtailing As(V) toxicity. Overall, the results indicated that NO is necessary for mitigation of As(V) stress by GABA in two studied vegetable crops but NO itself does not require GABA for the same.

     

An Appraisal of Ancient Molecule GABA in Abiotic Stress Tolerance in Plants,and Its Crosstalk with Other Signaling Molecules

Gamma-aminobutyric acid (GABA), a non-proteinaceous amino acid, is reported in prokaryotes and eukaryotes, since ancient times. However, it has gained attention in the present time because of its rapid accumulation during stressed conditions in plants as well as in the cyanobacteria. In plants, it regulates the number of physiological processes such as pollen tube growth, root growth, TCA cycle, N₂-metabolism, and osmoregulation. Several biotic and abiotic stresses prevail in the environment, which lead to enhanced accumulation of reactive oxygen species (ROS) thus causing oxidative damage. However, a rapid increase in the accumulation of GABA during stress in various plant forms like bacteria, cyanobacteria, fungi, and plants indicates its putative role in stress regulation and acclimation. This review summarizes the biosynthesis of GABA, its role in abiotic stress tolerance, and its crosstalk with ROS, nitric oxide, Ca⁺² ions, phytohormones, and polyamines in stress acclimation.