Abstract
Today, drought stress threatens the world seriously. Determining the effects of some exogenous stimulators in acquiring resistance against stress will contribute to agriculture under drought stress. In this regard, we investigated the effects of melatonin (MEL) on Morus nigra cv. 'Eksi Kara' (black mulberry) in challenging drought. To reach this object, we reproduced 'Eksi Kara', which is registered in Turkey and has economic importance, in tissue culture by using the meristem culture method. Plants were then transferred in a medium containing polyethylene glycol (PEG) 8000, which causes -1.5 MPa drought stress, and 20 μl MEL has applied. Leaf samples were taken on the 5th, 10th, and 15th days after treatments in groups of plants grown in a different medium (Control, Control+MEL, PEG and PEG+MEL). The changes in the pigment system, relative water content (RWC) and antioxidant system were evaluated comparatively between the groups to assess plants' growth and determine their roles in coping with stress. Our findings showed that RWC decreased in leaves under drought. Exogenous MEL added in MS medium had a mitigation effect on stress. The reduction was detected in the chlorophyll and carotenoid content of leaves. Moreover, MEL+PEG combination improved the chlorophyll level. It was seen that exogenous MEL application promoted the plant defence mechanism of M. nigra plants, which exposed to drought stress, by increasing the accumulation of non-enzymatic antioxidants; total glutathione (GSH), total phenolic, proline) and activities of antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), Glutathione-S-transferase (GST), glutathione reductase (GR), peroxidase (POD), ascorbate peroxidase (APX). This study also indicates that the application of MEL+PEG composition partially prevented membrane lipid peroxidation by decreasing (malondialdehyde) MDA content.
Highlights
Abiotic stress is the primary cause of yield loss worldwide, and it corresponds to more than 50% of yield loss in high-yield cultivated plants (Wang et al, 2004)
It was found that RWC decreased in the application of polyethylene glycol (PEG) to M. nigra leaves compared to the Control (p
There was a substantial decrease in RWC in different PEG group days (p
Summary
Abiotic stress is the primary cause of yield loss worldwide, and it corresponds to more than 50% of yield loss in high-yield cultivated plants (Wang et al, 2004). Drought is considered one of the significant abiotic stresses, and it alters the average growth balance in plants negatively. It damages plants' growth and productivity by causing a series of morphological, physiological, biochemical, and molecular changes (Pandey et al, 2017). (black mulberry) is in Urticales order Moraceae family and Morus genus. It has been reported that mulberry will have significant potential bio-energy plants in a rapidly changing global climate under drought conditions (Sekhar et al, 2017)
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