Abstract
The synthetic cytokinin 6-benzyladenine (6-BA) regulates plant growth and prevents the negative consequences of various forms of abiotic stress, including waterlogging in crop plants. The present study aimed to investigate the effects of exogenous 6-BA on the growth, oxidative stress, and ascorbate-glutathione (AsA-GSH) cycle system in the inbred SY-MY13 (waterlogging-resistant) and SY-XT1 (waterlogging-sensitive) seedlings of waxy corn in conditions of waterlogging stress. The results demonstrated that waterlogging stress causes chlorosis and necrosis in waxy corn leaves, inhibiting growth and leading to the accumulation of reactive oxygen species (ROS), which induces oxidative stress and, in turn, reduces membrane lipid peroxidation and the disruption of membrane homeostasis. This is specifically manifested in the increased concentrations of superoxide anion radicals (), hydrogen peroxide (H2O2), and malondialdehyde (MDA), in addition to increased relative electrical conductivity (REC%) values. The SY-MY13 strain exhibited growth superior to that of SY-XT1 when waterlogged due to its excellent waterlogging resistance. Thus, exogenous 6-BA was found to be effective in enhancing the growth of plants stressed by waterlogging in terms of the weight of the shoots and roots, shoot height, and leaf area. In addition to this, exogenous 6-BA also reduced the accumulation of , H2O2, and MDA, increased ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR) activity, and enhanced ascorbic acid (AsA), and reduced glutathione (GSH) concentration through the regulation of the efficiency of the AsA-GSH cycle system in maize plants. Hence, the application of exogenous 6-BA can alleviate waterlogging-induced damage and improve waterlogging tolerance in waxy corn via the activation of the AsA-GSH cycle system and the elimination of ROS.
Highlights
Climate change has compounded global environmental risks, affecting crop growth and jeopardizing food production and economic growth worldwide (Li et al, 2017; Tiwari et al, 2017; Maraci et al, 2018)
Treatment with 6-BA significantly increased the shoot height of SY-MY13 plants, there were no significant differences for other growth parameters between the two inbred lines in well-drained conditions
The results of the present study reveal that exogenous 6-BA is able to coordinate relative internal balance and the high activity of ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR), allowing adaptation to stress and enabling the balance between the production and scavenging of reactive oxygen species (ROS) through the modulation of the levels of the ascorbic acid (AsA)-reduced glutathione (GSH) cycle enzymes
Summary
Climate change has compounded global environmental risks, affecting crop growth and jeopardizing food production and economic growth worldwide (Li et al, 2017; Tiwari et al, 2017; Maraci et al, 2018). Of the heightened environmental risks, waterlogging has already been identified as among the most critical abiotic stresses affecting crop productivity. Waterlogging stress modifies the balance between the endogenous production and neutralization of reactive oxygen species (ROS), such as superoxide anion radicals (O−2 ), hydrogen peroxide (H2O2), etc., causing the accumulation of ROS that leads to oxidative stress in plants (Posso et al, 2018; Anee et al, 2019; Begum et al, 2019; Malhi et al, 2019; Park and Ju, 2019). Xiao et al (2020) concluded that the exposure of peach seedlings to waterlogging induced the accumulation of intracellular reactive ROS, in turn, causing apoptosis and impeding their growth and development. Excess ROS destroys physiological membrane activity, causing cell swelling and rupture (Zhang et al, 2007; Geetika et al, 2016; Sarwar et al, 2019)
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