Abstract
Drought stress is a major problem in wheat production but it could be managed by using various exogenous protectants such as gibberellic acid (GA). Although GA is a plant growth hormone, it shows a potential to protect the plant in stress conditions. To investigate the possible role of GA in mitigating drought stress, we treated wheat (<em>Triticum aestivum</em> ‘BARI Gom-21’) seedlings with a GA spray under semihydroponic conditions. In the experiment, the combined effect of GA and drought stress (induced by 12% polyethylene glycol) was studied after 48 h and 72 h. In the absence of exogenous GA, drought-stressed wheat seedlings showed various physiological and biochemical changes in a time-dependent manner. Malondialdehyde (MDA), hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and free proline (Pro) concentrations were increased, whereas catalase (CAT) and ascorbate peroxidase (APX) activities were reduced under drought stress. Gibberellic acid played a role in restoring the ascorbate (AsA) level, decreased the reduced/oxidized glutathione (GSH/GSSG) ratio and reduced monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) activities. Gibberellic acid significantly affected the glyoxalase system. Under drought stress, the methylglyoxal (MG) concentration was increased but GA application stimulated glyoxalase I (Gly I) and glyoxalase II (Gly II) activities to protect the wheat seedlings against stress. The study concluded that the severity of drought stress in wheat depends on the growth stage and it increases with an increase in the duration of stress, whereas exogenous GA helped the seedlings to survive by upregulating antioxidant defense mechanisms and the glyoxalase system.
Highlights
Plants are sessile organisms that have to face many unfavorable conditions due to their unstable and changing surroundings
The shortest plants were those grown under drought stress, whereas the maximum plant heights were found in the C+G treatment after 48 h and 72 h (Fig. 1)
Exogenous gibberellic acid (GA) increased the height of plants exposed to the drought stress by about 20% and 12% after 48 h and 72 h, respectively (Fig. 1)
Summary
Plants are sessile organisms that have to face many unfavorable conditions due to their unstable and changing surroundings. These stressful conditions include both biotic and abiotic stresses. The geographical distribution of plants may be affected which lead to decreases in plant productivity which could threaten food security. It has been reported that abiotic stress is responsible for most of the damage to plants, even as much as 50% [1]. Drought causes severe damage to plants in various ways, reducing growth by disrupting photosynthesis and other physiological functions, which reduce yield.
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