TABLE 4.

Role of melatonin in inducing heat stress tolerance in different plant species.

Crops	Heat stress	MT application	Effects	References
Wheat	40°C	100 μM	MT application reduced oxidative damages by lowering the TBARS and H2O2 contents and photosynthetic efficacy through enhanced activities of anti-oxidants	Iqbal et al., 2021
Tomato	42°C	10 μM	Exogenous MT increased the chlorophyll fluorescence, electron transport, efficacy of PS-1 and PS-II	Jahan et al., 2021
Wheat	42°C	100 μM	MT reduced the MDA and H2O2 accumulation and increased proline contents, and activities of APX, CAT, POD, SOD, and GSH and expression of stress-responsive genes (TaMYB80, TaWRKY26, and TaWRKY39)	Buttar et al., 2020
Tomato	42°C	100 μM	MT reduced the heat-induced oxidative stress, lowered the MDA contents, and enhanced the anti-oxidants spermidine and spermine contents and activities	Jahan et al., 2019
Rice	40.6°C	200 μM	MT alleviated the heat-induced damages to photosynthesis chlorophyll and improved the photosynthetic rate by enhancing the anti-oxidant activities	Barman et al., 2019
Kiwifruit	45°C	200 μM	MT pre-treatment ameliorates the head-induced damages by reducing the H2O2 contents and increasing the proline accumulation, activities, AsA, CAT, POD, SOD, DHAR, and MDHAR, and expression of glutathione S-transferase (GST) genes	Liang et al., 2018
Ryegrass	38/33°C (day/night)	10 μM	MT supplementation reduced the HS-induced leaf senescence. It increased plant height, biomass production, chlorophyll contents, photosynthetic rates, maintained the membrane stability, increased the CK contents, and decreased the ABA contents	Zhang et al., 2017a
Tomato	40°C	10 μM	MT supplementation increased the endogenous MT contents, expression of HSPs, chlorophyll contents and reduced the electrolyte leakage	Xu et al., 2016