Exogenous melatonin induces salt and drought stress tolerance in rice by promoting plant growth and defense system

Abstract

Due to global climate change, crops are certainly confronted with a lot of abiotic and biotic stress factors during their growth that cause a serious threat to their development and overall productivity. Among different abiotic stresses, salt and drought are considered the most devastating stressors with serious impact on crop’s yield stability. Here, the current study aimed to elucidate how melatonin works in regulating plant biomass, oxidative stress, antioxidant defense system, as well as the expression of genes related to salt and drought stress in rice plants. Eight groups of rice plants (3 replicates, 5 plants each) underwent varied treatments: control, melatonin, salt, drought, salt + drought, salt + melatonin, drought + melatonin, and salt + drought + melatonin. Melatonin (100 µM) was alternately applied a week before stress exposure; salt stress received 100 mM NaCl every 3 days for 3 weeks, and drought stress involved 10% PEG. Young leaves were randomly sampled from each group. The results showed that melatonin treatment markedly reduces salt and drought stress damage by promoting root, shoot length, fresh and dry weight, increasing chlorophyll contents, and inhibiting excessive production of oxidative stress markers. Salt and drought stress significantly decreased the water balance, and damaged cell membrane by reducing relative water contents and increasing electrolyte leakage. However, melatonin treated rice plants showed high relative water contents and low electrolyte leakage. Under salt and drought stress conditions, exogenous application of melatonin boosted the expression level of salt and drought stress responsive genes like OsSOS, OsNHX, OsHSF and OsDREB in rice plants. Taken together, our results reveal that melatonin treatment significantly increases salt and drought tolerance of rice plants, by increasing plant biomass, suppressing ROS accumulation, elevating antioxidants defense efficiency, and up-regulating the expression of salt and drought stress responsive genes.

Phytofabricated gold nanoparticles as modulators of salt stress responses in spinach: implications for redox homeostasis, biochemical and physiological adaptation

“…Our findings also unveiled that, salinity stress significantly reduced growth biomarkers ( Figure 2 ). This might be due to an imbalance in ROS production, membrane damage and changes in antioxidant machinery ( Khan et al., 2024 ); leading to impaired photosynthetic machinery ( Karumannil et al., 2023 ) and stomatal dynamical traits ( Wahid et al., 2022 ). However, following AuNPs treatment, the plants exhibited significant enhancements in various growth attributes.…”

Exogenous GABA Enhances Copper Stress Resilience in Rice Plants via Antioxidant Defense Mechanisms, Gene Regulation, Mineral Uptake, and Copper Homeostasis

“…They were soaked in water for four days at 32 °C in an incubator, as per Jan, R., et al [ 43 ]. Pre-germinated seeds were then planted in a specialized soil mix (Doobaena plus) consisting of cocopeat (27%), peat moss (10%), vermiculite (34%), Masato (10%), diatomite (13%), bara mesh (5.5%), fertilizer (0.48%), and humectant (0.2%), provided by Nongkyung Co. Ltd. (Yeongcheon-si, Republic of Korea) [ 44 ]. Eight groups of rice plants, five plants per group, were established and grown for 10 days: control only treated with water (CK), 50 μM copper treated (C50), 50 μM copper and GABA treated (C50+G), 100 μM copper treated (C100), 100 μM copper and GABA treated (C100+G), 200 μM copper treated (C200), 200 μM copper and GABA treated (C200+G), and GABA treated (G) plants.…”

“…One month after applying the stress, plant growth including shoot length, root length, and fresh weight were measured, while for the assessment of dry weight (DW) of seedlings, the whole plant including roots and shoots, underwent oven drying at 200 °C for 30 min, followed by maintenance at 60 °C for 48 h, and then weight was calculated [ 44 ].…”

“…To measure GSH (Glutathione) content, we used the method of [ 52 ] with some modifications and a method used in our pervious study [ 44 ]. Briefly, leaf samples were ground in liquid nitrogen and treated with 10% trichloroacetic acid.…”

Mitigating Effect of Exogenous Melatonin on Salt and Drought Stress in Cyperus esculentus L. during the Tillering Stage

“…Although Cyperus esculentus L. itself has a certain level of salt and drought tolerance, stress conditions increase the threshold of reactive oxygen species, which means that C. esculentus plants use physiological, biochemical, and molecular mechanisms to cope with these pressures in the face of external drought and salinity stress [12]. In the process of salt and drought stress, all of the key processes in plant growth, such as photosynthesis, protein synthesis, energy metabolism, and osmotic regulation, are affected to varying degrees [13]. Both drought and salt stress can cause ion toxicity in cells, resulting in osmotic imbalances in plants and thus affecting plant growth and development [14].…”