title: Manganese-induced salt stress tolerance in rice seedlings: regulation of ion homeostasis, antioxidant defense and glyoxalase systems.
abstract: Hydroponically grown 12-day-old rice (Oryza sativaL. cv. BRRI dhan47) seedlings were exposed to 150 mM NaCl alone and combined with 0.5 mM MnSO4. Salt stress resulted in disruption of ion homeostasis by Na+influx and K+efflux. Higher accumulation of Na+and water imbalance under salinity caused osmotic stress, chlorosis, and growth inhibition. Salt-induced ionic toxicity and osmotic stress consequently resulted in oxidative stress by disrupting the antioxidant defense and glyoxalase systems through overproduction of reactive oxygen species (ROS) and methylglyoxal (MG), respectively. The salt-induced damage increased with the increasing duration of stress. However, exogenous application of manganese (Mn) helped the plants to partially recover from the inhibited growth and chlorosis by improving ionic and osmotic homeostasis through decreasing Na+influx and increasing water status, respectively. Exogenous application of Mn increased ROS detoxification by increasing the content of the phenolic compounds, flavonoids, and ascorbate (AsA), and increasing the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), superoxide dismutase (SOD), and catalase (CAT) in the salt-treated seedlings. Supplemental Mn also reinforced MG detoxification by increasing the activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) in the salt-affected seedlings. Thus, exogenous application of Mn conferred salt-stress tolerance through the coordinated action of ion homeostasis and the antioxidant defense and glyoxalase systems in the salt-affected seedlings.
authors.affiliation: Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0795 Japan ; Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, 1207 Bangladesh.
authors.forename: Anisur
authors.initials: A
authors.lastname: Rahman
authors.affiliation: Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0795 Japan.
authors.forename: Md Shahadat
authors.initials: MS
authors.lastname: Hossain
authors.affiliation: Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0795 Japan ; Department of Agroforestry and Environmental Science, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, 1207 Bangladesh.
authors.forename: Jubayer-Al
authors.initials: JA
authors.lastname: Mahmud
authors.affiliation: Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0795 Japan ; Department of Agricultural Botany, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, 1207 Bangladesh.
authors.forename: Kamrun
authors.initials: K
authors.lastname: Nahar
authors.affiliation: Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, 1207 Bangladesh.
authors.forename: Mirza
authors.initials: M
authors.lastname: Hasanuzzaman
authors.affiliation: Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0795 Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Fujita
keywords: Methylglyoxal; Nutrient homeostasis; Osmotic stress; Oxidative stress; Reactive oxygen species; Trace elements