Potassium-Induced Regulation of Cellular Antioxidant Defense and Improvement of Physiological Processes in Wheat under Water Deficit Condition

Drought is the most common form of abiotic stress that reduces plant growth and productivity.It causes plant injuries through elevated production of reactive oxygen species(ROS).Potassium(K)is a vital plant nutrient that notably ameliorates the detrimental effect of drought stress in the plant.A pot experiment was conducted at the Laboratory of Plant Stress Responses,Faculty of Agriculture,Kagawa University,Japan,under controlled environment of green house to explore the role of K in mitigating drought severity in wheat(Triticum asevitum L.)seedlings.Three days after germination,seedlings were exposed to three water regimes viz.,100,50,and 20%field capacity(FC)for 21 days.Potassium was adjusted in Hoagland nutrient solution at 0,6 and 12 mM concentration and applied to pot instead of normal water.Results show that,water deficit stress notably reduced plant growth,biomass accumulation,leaf relative water content(RWC)along with reduced photosynthetic pigments.Increased amount of biochemical stress markers viz.,malondialdehyde(MDA),hydrogen peroxide(H_(2)O_(2)),methylglyoxal(MG),proline(Pro)as well as an impaired antioxidant defense system were observed in drought affected wheat plants.On the contrary,K supplementation resulted in improvement of biochemical and physiological parameters that worked behind in improving growth and development of the wheat plants.In addition,enzymes of ascorbateglutathione(AsA-GSH)cycle were also enhanced by supplemented K that accelerated the ROS detoxification process in plant.Although glyoxalse system did not performed well till MG was detoxified might following another short stepped pathways.Our results revealed that drought stressed plants showed better performances in terms of biochemical and physiological attributes,antioxidant defense and glyoxalase system,as well as ROS detoxification due to K supplementation with better performance at 12 mM K added in 50%FC growing condition.

Targeting Glycinebetaine for Abiotic Stress Tolerance in Crop Plants:Physiological Mechanism,Molecular Interaction and Signaling

In the era of climate change,abiotic stresses(e.g.,salinity,drought,extreme temperature,flooding,metal/metalloid(s),UV radiation,ozone,etc.)are considered as one of the most complex environmental constraints that restricts crop production worldwide.Introduction of stress-tolerant crop cultivars is the most auspicious way of surviving this constraint,and to produce these types of tolerant crops.Several bioengineering mechanisms involved in stress signaling are being adopted in this regard.One example of this kind of manipulation is the osmotic adjustment.The quarternary ammonium compound glycinebetaine(GB),also originally referred to as betaine is a methylated glycine derivative.Among the betaines,GB is the most abundant one in plants,which is mostly produced in response to dehydration caused by different abiotic stresses like drought,salinity,and extreme temperature.Glycinebetaine helps in decreased accumulation and detoxification of ROS,thereby restoring photosynthesis and reducing oxidative stress.It takes part in stabilizing membranes and macromolecules.It is also involved in the stabilization and protection of photosynthetic components,such as ribulose-1,5-bisphosphate carboxylase/oxygenase,photosystem II and quarternary enzyme and protein complex structures under environmental stresses.Glycinebetaine was found to perform in chaperone-induced protein disaggregation.In addition,GB can confer stress tolerance in very low concentrations,and it acts in activating defense responsive genes with stress protection.Recently,field application of GB has also shown protective effects against environmental adversities increasing crop yield and quality.In this review,we will focus on the role of GB in conferring abiotic stress tolerance and the possible ways to engineer GB biosynthesis in plants.