Glycine-betaine induced salinity tolerance in maize by regulating the physiological attributes, antioxidant defense system and ionic homeostasis

Zain Dustgeer,Bushra A Alhammad,Imran Khan,Muhammad U Hassan,Mahmoud F Seleiman,Yahya Refay,Rewaa S Jalal,Muhammad U Chattha,Esmat F Ali

doi:10.15835/nbha49112248

Abstract

The plants are exposed to different abiotic stresses, including the salinity stress (SS) that negatively affect the growth, metabolism, physiological and biochemical processes. Thus, this study investigated the effect of diverse levels of foliar-applied GB (0 control, 50 mM and 100 mM) on maize growth, membrane stability, physiological and biochemical attributes, antioxidant enzymes and nutrients accumulation under different levels of SS (i.e., control, 6 dS m-1, 12 dS m-1). Salt stress diminished the root and shoot length, root and shoot biomass, chlorophyll contents, photosynthetic rate (Pn), stomatal conductance (gs), relative water contents (RWC), soluble proteins (SP) and free amino acids; (FAA); and increased activities of antioxidant enzymes, electrical conductivity (EC) and accumulation of malondialdehyde (MDA), hydrogen peroxide (H2O2), Na+ and Cl− ions. GB application significantly increased root and shoot growth, leaves per plant, shoots length, chlorophyll contents, gs, Pn and membrane stability by reducing MDA and H2O2 accumulation. Moreover, GB also increased the SP, FAA accumulation, activities of antioxidant enzymes and Na+ and Cl- exclusion by favouring Ca2+ and K+ accumulation. In conclusion, the foliar-applied GB increased Pn, gs, ant-oxidants activities, and accumulation of SP and FAA; and reduced the accretion of Na+ and Cl− by favouring the Ca2+ and K+ accretion which in turns improved growth under SS.

Highlights

Salinity stress (SS) is one of the critical factors of abiotic stress that substantially diminishes crop growth, development, and production (Mbarki et al, 2018; Seleiman and Kheir, 2018; Seleiman, 2019; Seleiman et al, 2020)
The reduction in growth traits was noted under all SS levels, but the maximum reduction was recorded with the highest SS level (i.e. 12 dS m-1) (Table 1)
The maximum LPP (6) was recorded from plants grown in control with the application of 100 mM GB, and lowest LPP (3) was recorded from plants grown with the highest SS level (i.e. 12 dS m-1) without foliar-applied GB (Table 1)

Summary

Introduction

Salinity stress (SS) is one of the critical factors of abiotic stress that substantially diminishes crop growth, development, and production (Mbarki et al, 2018; Seleiman and Kheir, 2018; Seleiman, 2019; Seleiman et al, 2020). The effects of salt stress have been reported in most of the world's crops (Seleiman and Kheir, 2018; Al-Ashkar et al, 2020), including maize, which is the most imperative staple food of many nations. Salinity stress has a drastic effect on plant morphology and physiology due to the physiologically mediated osmotic stress. This can result imperfections in plant water relations and ionic balance that eventually leads to ionic toxicity of plant metabolic processes (Semida et al, 2016; Al-Ashkar et al, 2019; Seleiman et al, 2020). SS can induce the overproduction of reactive oxygen species (ROS), which triggers the oxidative stress (OS) in different plant tissues, and causes chlorophyll degradation and oxidation of significant molecules including lipids, proteins and DNA (Radi, 2018)

Methods

Results

Discussion

Conclusion