The ameliorative effects of exogenous melatonin on grape cuttings under water‐deficient stress: antioxidant metabolites, leaf anatomy, and chloroplast morphology

Abstract

Grapes are an important economic crop and are widely cultivated around the world. Most grapes are grown in arid or semi-arid regions, and droughts take a heavy toll in grape and wine production areas. Developing effective drought-resistant cultivation measures is a priority for viticulture. Melatonin, an indoleamine, mediates many physiological processes in plants. Herein, we examined whether exogenously applied melatonin could improve the resistance of wine grape seedlings grown from cuttings to polyethylene glycol-induced water-deficient stress. The application of 10% polyethylene glycol (PEG) markedly inhibited the growth of cuttings, caused oxidative stress and damage from H2 O2 and O2∙-, and reduced the potential efficiency of Photosystem II and the amount of chlorophyll. Application of melatonin partially alleviated the oxidative injury to cuttings, slowed the decline in the potential efficiency of Photosystem II, and limited the effects on leaf thickness, spongy tissue, and stoma size after application of PEG. Melatonin treatment also helped preserve the internal lamellar system of chloroplasts and alleviated the ultrastructural damage induced by drought stress. This ameliorating effect may be ascribed to the enhanced activity of antioxidant enzymes, increased levels of nonenzymatic antioxidants, and increased amount of osmoprotectants (free proline). We conclude that the application of melatonin to wine grapes is effective in reducing drought stress.

Melatonin production in Escherichia coli by dual expression of serotonin N-acetyltransferase and caffeic acid O-methyltransferase

“…Treating various plant species with low concentrations of exogenous melatonin (<1 μM) promotes root and coleoptile growth (Hernández-Ruiz et al 2005;Chen et al 2009) and ameliorates stress injury due to salt , alkaline soda stress (Liu et al 2015), drought (Meng et al 2014), and oxidative stress (Dan et al 2015). In addition to mitigating effects on abiotic stressors, melatonin participates in the response to pathogen attack as a signaling molecule by enhancing salicylic acid levels, resulting in resistance to infection (Lee et al , 2015.…”

Arabidopsis serotonin N‐acetyltransferase knockout mutant plants exhibit decreased melatonin and salicylic acid levels resulting in susceptibility to an avirulent pathogen

“…As a primary metabolite, it acts as a growth regulator in developmental processes including coleoptile growth , root growth , leaf morphology , flowering timing , and fruit ripening . As a secondary metabolite, it is associated with tolerance to biotic and abiotic stresses including pathogens , senescence , drought , peroxidizing herbicide , cold , salt , and high temperature . All of these stress tolerance mechanisms are closely associated with enhanced melatonin production and the induction of genes corresponding to various stresses .…”

Beneficial Roles of Melatonin on Redox Regulation of Photosynthetic Electron Transport and Synthesis of D1 Protein in Tomato Seedlings under Salt Stress

“…Melatonin improves the functions of stomata, through the maintenance of the water balance and down-regulated the ABA pathway in Malus hupehensis through under drought stress (Li et al, 2015). Melatonin contributes to the efficiency of electron transport under conditions of water deficiency (Wang et al, 2013; Zhang et al, 2013; Meng et al, 2014). However, to avoid damage from excess electrons in the chloroplast, (e.g., ROS), melatonin plays a protective role by directly scavenging ROS and also by up-regulating the antioxidant enzymes and antioxidants (Arnao and Hernández-Ruiz, 2015; Li et al, 2016).…”