Exogenous 6-Benzyladenine Improves Waterlogging Tolerance in Maize Seedlings by Mitigating Oxidative Stress and Upregulating the Ascorbate-Glutathione Cycle

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 (O2-), 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 O2-, 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.

N7‐SSPP fusion gene improves salt stress tolerance in transgenic Arabidopsis and soybean through ROS scavenging

“…It has been previously shown that the increased synthesis and response of cytokinins (CTKs) leads to enhanced scavenging capability of ROS. For example, the application of synthetic CTK 6‐benzyladenine (6‐BA) improved waterlogging tolerance in maize seedlings via the elimination of ROS (Wang et al, 2021). The activities of antioxidant enzymes were promoted by exogenously applied kinetin, thereby protecting tomato plants against NaCl‐induced oxidative stress (Ahanger et al, 2018).…”

Drought and flooding resistances of maize germplasm are compared and evaluated using a multivariate analysis method

“…On the other hand, APX and POD catalyze the conversion of H 2 O 2 to O 2 − (Lin et al, 2004; Salah et al, 2019), leading to the low content of H 2 O 2 accumulated in both drought and flooding stresses. Moreover, the more accumulation of ROS in flooding stress or drought stress is, the more membrane lipid peroxidation and damage membrane homeostasis are, ultimately accelerating leaf senescence and inhibiting the growth of plants (LIU et al, 2010; Wang et al, 2021). All the above give us new insights into understanding the different scavenging mechanisms of ROS and the adaptive growth mechanism of maize in response to drought and flooding stresses.…”

Sandbur Drought Tolerance Reflects Phenotypic Plasticity Based on the Accumulation of Sugars, Lipids, and Flavonoid Intermediates and the Scavenging of Reactive Oxygen Species in the Root

“…Stress responses are often associated with redox homeostasis and normally lead to a rapid and transient increase in the levels of intracellular ROS [ 57 , 58 ]. Plants have evolved an efficient ROS scavenging system to maintain redox homeostasis under stress including enzymatic components such as GSTs [ 59 , 60 ] and metabolic components such as ascorbate and glutathione, forming the ASC–GSH cycle [ 61 , 62 , 63 ]. This system ensures the efficient removal of hydrogen peroxides and lipid peroxides [ 64 ].…”