Glycine Betaine-Mediated Root Priming Improves Water Stress Tolerance in Wheat (Triticum aestivum L.)

Abstract

Droughts represent one of the main challenges that climate change imposes on crop production. As a globally cultivated staple crop, wheat (Triticum aestivum L.) is prone to drought environments. Therefore, improvement in drought tolerance represents a growing concern to ensure food security, especially for wheat. In this perspective, the application of Phyto-phillic exogenous materials such as glycine-betaine (GB) has been attracting attention, particularly in stress-related studies. Since roots procure the water and nutrients for plants, any improvements in their response and capacity against drought stress could induce stress tolerance in plants. However, the knowledge about the changes in root architecture, defense mechanism, hormonal metabolism, and downstream signaling, in response to GB-mediated root priming, is still limited. Therefore, we designed the present study to investigate the role of GB-mediated root priming in improving the water stress tolerance in wheat (cv. Jimai-22) under in-vitro conditions. The roots of twelve days old wheat seedlings were treated with Hoagland’s solution (GB-0), 50 mM GB (GB-1), and 100 mM GB (GB-2) for 48 h and subjected to well-watered (WW) and water-stress (WS) conditions. The osmotic stress substantially impaired shoot/root growth, dry matter accumulation, and increased malondialdehyde (MDA) and hydrogen-peroxide (H2O2) production in the roots of wheat seedlings. However, GB-mediated root priming improved the redox homeostasis of wheat roots by boosting the activities of SOD and POD and triggering the significantly higher accumulation of abscisic acid (ABA) and salicylic acid (SA) in the roots of GB-primed plants. Consequently, it modified the root architecture system and improved plant growth, dry matter accumulation, and water-stress tolerance of wheat seedlings. Moreover, GB-mediated root priming increased root sensitivity to water stress and induced overexpression of stress-responsive genes involved in ABA metabolism (TaNECD1, TaABA’OH2), their downstream signal transduction (TaPP2C, TaSNRK2.8), and activation of different transcriptional factors (TabZIP60, TaAREB3, TaWRKY2, TaERF3, and TaMYB3) that are associated with plant metabolite accumulation and detoxification of ROS under water stress conditions. Overall, our results demonstrated that GB-priming improved the physiological and biochemical attributes of wheat plants under WS conditions by improving the drought perception capacity of wheat roots, ultimately enhancing the water stress tolerance. Thus, the GB-priming of roots could help to enhance the water-stress tolerance of economically important crops (i.e., wheat).

Abscisic acid and glycine betaine-mediated seed and root priming enhance seedling growth and antioxidative defense in wheat under drought

“…Proline and soluble sugars as well as other osmoregulatory substances can be significantly increased by exogenous ABA signaling resulting in improved osmotic adjustment in plants [ 89 ]. The findings in this study are supported with other studies in relation to the accumulation of proline under ABA and GB application for the enhancement of drought tolerance in wheat and other plants [ 57 , 68 , 90 , 91 ]. The plants with ABA and GB application enhanced drought tolerance might be due to the increased expressions of genes at the transcription level.…”

“…However, we were not able to measure the activities of these enzymes which is a major limitation of this study. Previous reports confirmed the increased production of enzymatic antioxidants under drought conditions combined with the exogenous application of ABA and GB in plants [ 21 , 22 , 37 , 57 , 68 , 84 ].…”

“…Several reports suggested that the pre-treatment of ABA and GB increased seedling growth in many crop plants under different abiotic stress conditions [ 58 , 66 [58] , [66] , [67] , [68] [58] , [66] , [67] , [68] ]. ABA has been reported to improve seed dormancy, germination, dormancy as well as vegetative growth in plants [ 69 , 70 ].…”

“…On the other hand, GB is an important compatible solute that might improve seedling growth in all wheat cultivars by improving the tissue water status and maintaining the osmotic balance for proper root and shoot growth [ 24 ]. Previous reports also highlighted the enhancement of drought tolerance with the exogenous application of GB in wheat and other crop plants [ 37 , 68 , 77 ].…”

Advancing horizons in vegetable cultivation: a journey from ageold practices to high-tech greenhouse cultivation—a review

“…There is growing interest in anti-stress compounds. For example, osmoprotectants counteract the negative impacts of environmental stressors ( Ahmed et al., 2021a ). In onions, proline has been a game-changer for mitigating drought-induced stress ( Semida et al., 2020 ).…”