Exogenous Application of Melatonin Improves Drought Tolerance in Coffee by Regulating Photosynthetic Efficiency and Oxidative Damage

Abstract

The protective role of melatonin in plants under abiotic stress has been reported, but little information is available on its mitigation effect on coffee (Coffea arabica) plants. The objective of this study was to determine the effect of exogenous application of 100 µM melatonin in coffee leaves under 3 months of drought stress treatment. Melatonin was found to alleviate the drought-induced damage in coffee through reducing the rate of chlorophyll degradation, electrolyte leakage, malonaldehyde content, and activating various antioxidant enzymes, such as catalase, guaiacol peroxidase, and superoxide dismutase. Melatonin application suppressed the expression of chlorophyll degradation gene PAO encoding pheophorbide a oxygenase, and upregulated the expression of photosynthetic gene RBCS2 encoding ribulose-1,5-bisphosphate oxygenase (Rubisco) protein, and a drought-related gene AREB encoding abscisic acid-responsive element binding protein. The photosynthetic efficiency of photosystem II under dark adaptation was also improved upon melatonin application in drought-stressed plants. Our results showed that both foliar spray and direct soil application of melatonin could improve drought tolerance by regulating photosynthetic efficiency and oxidative damage in C. arabica seedlings. This study provides insights in application of melatonin as a protective agent against drought stress in improvement of crop yields.

Melatonin Mediated Differential Regulation of Drought Tolerance in Sensitive and Tolerant Varieties of Upland Cotton (Gossypium hirsutum L.)

“…Electrolytic leakage indicates membrane damage, which is a common detrimental effect of drought stress, with the primary cause being lipid peroxidation ( Cherono et al, 2020 ; Sadak et al, 2020 ). Here, elevated MDA and electrolytic leakage levels indicate the pernicious effect of drought stress in L-799, but the non-significant changes in Suraj suggest its stress-tolerance nature ( Figure 6 ).…”

“…Frozen leaf samples (a true third leaf) (150–200 mg) were used to extract the crude protein for enzyme activity assays, following the procedure of Cherono et al (2020) . Superoxide dismutase (SOD, EC 1.15.1.1) activity was determined using nitro blue tetrazolium (NBT), following Beauchamp and Fridovich (1971) .…”

Melatonin-Mediated Abiotic Stress Tolerance in Plants

“…Drought restricts plant growth and development. It is also a severe threat to crop productivity and quality because of alterations to the morphological, physiological, biochemical, and molecular features of plants ( Cherono et al, 2021 ). Drought induces oxidative stress and activates stress signaling pathways mediated by ROS, Ca 2+ , and hormones.…”

Melatonin-Induced Protection Against Plant Abiotic Stress: Mechanisms and Prospects

“…MT supply also suppressed the expression of chlorophyll degradation genes [pheophorbide a oxygenase (PAO)], which improves the chlorophyll synthesis under stress conditions. MT also increases the expression of photosynthetic genes (RBCS2), thereby improving overall photosynthetic efficiency, assimilating production and crop growth under drought stress ( Cherono et al, 2021 ).…”