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Abstract
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The involvement of melatonin in the regulation of salt stress acclimation has been
shown in plants in this present work. We found that the GOAL cultivar of wheat
(Triticum aestivum L.) was the most salt-tolerant among the investigated cultivars,
GOAL, HD-2967, PBW-17, PBW-343, PBW-550, and WH-1105 when screened
for tolerance to 100 mM NaCl. The application of 100 μM melatonin maximally
reduced oxidative stress and improved photosynthesis in the cv. GOAL. Melatonin
supplementation reduced salt stress-induced oxidative stress by upregulating the
activity of antioxidant enzymes, such as superoxide dismutase (SOD), ascorbate
peroxidase (APX), and glutathione reductase (GR), and reduced the glutathione
(GSH) production. This resulted in increased membrane stability, photosynthetic-N
use efficiency and photosynthesis in plants. The application of 50 μM of the ethyl-
ene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) in the presence of mela-
tonin and salt stress increased H 2 O 2 content but reduced GR activity and GSH,
photosynthesis, and plant dry mass. This signifies that melatonin-mediated salt
stress tolerance was related to ethylene synthesis as it improved antioxidant activ-
ity and photosynthesis of plants under salt stress. Thus, the interaction of melato-
nin and ethylene bears a prominent role in salt stress tolerance in wheat and can be
used to develop salt tolerance in other crops.
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