Melatonin alleviates drought impact on growth and essential oil yield of lemon verbena by enhancing antioxidant responses, mineral balance, and abscisic acid content

Abstract

Melatonin has recently emerged as a multifunctional biomolecule with promising aspects in plant stress tolerance. The present study examined the effects of foliar-sprayed melatonin (0, 100, and 200 μM) on growth and essential oil yield attributes of lemon verbena (Lippia citriodora) under water-shortage (mild, moderate and severe). Results revealed that melatonin minimized drought effects on lemon verbena, resulting in improved growth and essential oils yield. Drought impositions gradually and significantly reduced several growth parameters, such as plant height and biomass, whereas melatonin application revived the growth performance of lemon verbena. Melatonin protected the photosynthetic pigments and helped maintain the mineral balance at all levels of drought. Melatonin stimulated the accumulation of proline, soluble sugars and abscisic acid, which were positively correlated with a better preservation of leaf water status in drought-stressed plants. Melatonin also prevented oxidative damages by enhancing the superoxide dismutase, ascorbate peroxidase and catalase activities. Furthermore, increased levels of total phenolic compounds, chicoric acid, caffeic acid and chlorogenic acid, as well as ascorbate and total antioxidant capacity in melatonin-sprayed drought-stressed plants indicated that melatonin helped verbena plants to sustain antioxidant and medicinal properties during drought. Finally, melatonin treatments upheld the concentrations and yield of essential oils in the leaves of lemon verbena regardless of drought severities.These results provided new insights into melatonin-mediated drought tolerance in lemon verbena, and this strategy could be implemented for the successful cultivation of lemon verbena, and perhaps other medicinal plants, in drought-prone areas worldwide.

Melatonin Promotes SGT1-Involved Signals to Ameliorate Drought Stress Adaption in Rice

“…Oxidative products, i.e., H 2 O 2 , could activate the antioxidant system to maintain redox homeostasis, but excess accumulation would damage the antioxidant system [ 37 ]. Melatonin is thought to promote the antioxidant system to scavenge ROS, even under severe drought stress, such as 25% FC [ 38 ]. To detect whether the mutation of OsSGT1 affected the promoted effects of melatonin on antioxidant system under drought stress, activities of the enzymatic SOD, CAT, APX, GR, and content of the nonenzymatic ASA and GSH, were further investigated.…”

Exogenous melatonin mitigates salinity‐induced damage in olive seedlings by modulating ion homeostasis, antioxidant defense, and phytohormone balance

“…Frozen leaves (0.5 g, −80°C) from each sample were extracted in 5 mL extraction buffer as described previously (Hosseini et al 2021). After centrifugation, the supernatant was collected and used to determine the activities of antioxidant enzymes, including SOD (EC 1.15.1.1), CAT (EC 1.11.1.6.…”

“…The applications of exogenous chemicals, such as melatonin (MEL), abscisic acid (ABA), salicylic acid, and brassinolides, have been used to increase the potential of plants to deal with different abiotic stresses, including salinity (Csiszar et al 2018; Hosseini et al 2021; Ren et al 2018; Tanveer et al 2018; Zahedi et al 2019; Zahedi et al 2020). MEL, a hormone‐like compound found in plants, has been used to enhance salt tolerance in several fruit crops, including sour orange ( Citrus aurantium ; Kostopoulou et al 2015), tomato ( Solanum lycopersicum ; Martinez et al 2018), and strawberry ( Fragaria sp.…”

Melatonin-Mediated Abiotic Stress Tolerance in Plants

“…Exogenous melatonin treatment can trigger an increase in endogenous melatonin levels, thereby improving turgor pressure, cell stability, chlorophyll recovery, and photosynthetic machinery stability under drought stress ( Meng et al, 2014 ; Ding et al, 2018 ). Furthermore, melatonin treatment can promote seed germination, lateral root formation, hypocotyl elongation, vegetative growth, and fruit quality during drought ( Hosseini et al, 2021 ; Sun et al, 2021 ). In rapeseed, seed priming with melatonin improves stomatal and ultrastructural traits, as well as osmotic adjustment, thus improving drought tolerance ( Khan et al, 2019 ).…”