Exogenous Melatonin Activates Antioxidant Systems to Increase the Ability of Rice Seeds to Germinate under High Temperature Conditions

Abstract

High temperatures are a major concern that limit rice germination and plant growth. Although previous studies found that melatonin can promote seed germination, the physiological regulation mechanism by which exogenous melatonin mediates high temperature tolerance during rice seed germination is still largely unknown. In order to overcome these challenges, the present study investigates the effects of melatonin on the characteristics of rice seed germination as well as on antioxidant properties, under different high temperature conditions. The results show that 100 μM melatonin seed-soaking treatment under high temperature conditions effectively improves the germination potential, the germination index, and the vigor index of rice seeds; increases the length of the shoot and the root; improves the activity of the antioxidant enzymes; and significantly reduces the malondialdehyde content. The gray relational grade of the shoot peroxidase activity and the melatonin soaking treatment was the highest, which was used to evaluate the effect of melatonin on the heat tolerance of rice. The subordinate function method was used to comprehensively evaluate the tolerance, and the results show that the critical concentration of melatonin is 100 μM, and the critical interactive treatment is the germination at 38 °C and followed by the recovery at 26 °C for 1 day + 100 μM. In conclusion, 100 μM of melatonin concentration improved the heat resistance of rice seeds by enhancing the activity of the antioxidant enzymes.

Melatonin-mediated temperature stress tolerance in plants

“…It also enhanced the activities of antioxidant enzymes, protein, and lipid molecules and favored the lower production of H 2 O 2 and MDA 74 Strawberry ( Fragaria × ananassa Duch.) 35°C and 40°C 0, 50, and 100 μM MET treatment decreased heat injury symptoms and induced antioxidant mechanisms, also up-regulated the expression of defense HSF ( FaTHsfA2a, FaTHSFB1a ) and HSP ( HSP90 ) genes 75 Rice ( Oryza sativa L.) 38 ◦C 0, 20, 100, 500 µM MET treatment improved the heat tolerance of rice seeds by enhancing the activity of the antioxidant enzymes and significantly reducing the MDA content 76 Tomato ( Solanum lycopersicum L.) 40°C, 7 d 50 mM MET alleviated the oxidative damage of PSII by balancing the electron transfer of the donor side, reaction center, and receptor side 77 Rice ( Oryza sativa L.) 38°C/28°C 250 mL of 200 μmol L −1 MET improved the stress resistance by enhancing the scavenging efficiency of ROS and improved the leaf photosynthetic and heat-resistance properties. 78 Abbreviations: Abscisic acid (ABA); ascorbate peroxidase (APX); cold stress (CS); cytokinin (CK); chlorophyll (Chl); catalase (CAT); glutathione reductase (GSSG-R); gibberellic acid (GA3); heat stress (HS); hydrogen peroxide (H 2 O 2 ); heat shock proteins (HSPs); indole-3-acetic acid (IAA); malondialdehyde (MDA); melatonin (MET); peroxidase (POD); reactive oxygen species (ROS); superoxide dismutase (SOD); zeatin (ZT).…”

Crosstalk between Melatonin and Reactive Oxygen Species in Plant Abiotic Stress Responses: An Update

“…The increase in melatonin alleviated the inhibition of germination and growth of plants, such as Arabidopsis , rice, watermelon, Camellia sinensis , cucumber, tomato, soybean, Chrysanthemum , Actinidia deliciosa , etc. [ 15 , 37 , 38 , 44 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ] ( Table 1 ). Similar to salinity and drought stresses, cold or heat stress induced severe oxidative stress, and melatonin increased APX, SOD, CAT, POD, GPX, GR, Gly I, and Gly II activity, as well as GSH, ASC, proline, flavonoid, and proline contents.…”

The antioxidant system response to drought-stressed Diospyros lotus treated with exogenous melatonin

“…Many studies demonstrated the dose-dependent response of melatonin in plants tolerant to salt ( Ahmad et al, 2021a ), cold ( Chang et al, 2022 ), high temperature ( Yu et al, 2022 ), and heavy metals ( Nabaei & Amooaghaie, 2019 ). Ahmad et al (2019) found that foliar application of 100 µM was more effective in improving maize seedling’s drought tolerance than 50 and 75 µM melatonin application.…”