Exogenous melatonin improved potassium content in Malus under different stress conditions

Abstract

Melatonin mediates many physiological processes in plants. We investigated its role in regulating growth, potassium uptake, and root system architecture under three types of stress: salinity or a deficiency of all nutrients in Malus hupehensis Rehd., as well as a K deficiency in Malus rockii Rehd. Each treatment caused a reduction in growth rates and disrupted the absorption of potassium. However, pretreatment with 0.1 mmol/L melatonin significantly alleviated such inhibitions. The addition of melatonin also upregulated genes for antioxidant enzymes involved in the ascorbate-glutathione cycle (MdcAPX, MdDHAR1, MdDHAR2, MdMDHAR, and MdcGR) and helped decrease the accumulation of H2 O2 while improving the expression of K transporters and genes for the CBL1-CIPK23 pathway. These results indicated that melatonin can regulate the ROS signal and activate the CBL1-CIPK23 pathway to regulate the expression of a potassium channel protein gene, thereby promoting the absorption of potassium ions. Our findings demonstrate that inducing melatonin production is an important mechanism for plant defenses that can serve as a platform for possible applications in agricultural or related fields of research.

Melatonin Improves Waterlogging Tolerance of Malus baccata (Linn.) Borkh. Seedlings by Maintaining Aerobic Respiration, Photosynthesis and ROS Migration

“…It is well known that various stressors induce melatonin production in plants as well as in animals (Byeon et al, 2012; Li C. et al, 2016; Xu et al, 2016). This is considered as self-defense of organisms against external insults (Tan et al, 2015).…”

“…Melatonin was identified in plants in Dubbels et al (1995) and Hattori et al (1995). Since then it has been reported to exist in many plants and plant products (Ramakrishna et al, 2012; Yip et al, 2013; Shi et al, 2015b; Zhao et al, 2015a; Li C. et al, 2016; Ma et al, 2016; Xu et al, 2016). Different from other antioxidants, it is an amphiphilic molecule which makes it distribute in all cellular compartments including cytosol, membrane, mitochondria and chloroplasts (López et al, 2009; Byeon et al, 2013; Back et al, 2016).…”

“…Also, melatonin as well as its metabolites can eliminate different kinds of ROS including superoxide anion $\left({\mathrm{O}}_2^{•-}\right)$, hydrogen peroxide (H 2 O 2 ), hydroxyl radical ( • OH), singlet oxygen ( 1 O 2 ), peroxynitrite anion (ONOO - ) and nitric oxide (NO) (Tan et al, 2013). Melatonin has been reported to protect plants against a variety of abiotic and biotic stresses (Zuo et al, 2014; Liang et al, 2015; Liu et al, 2015; Shi et al, 2015a; Wang et al, 2015; Zhao et al, 2015b; Li C. et al, 2016; Xu et al, 2016). The transgenic Arabidopsis plants, ecotopically expressing melatonin synthetic gene MzASMT1 , had higher endogenous melatonin production and significantly lower ROS than that of their wild types.…”

Overexpression of rice serotonin N‐acetyltransferase 1 in transgenic rice plants confers resistance to cadmium and senescence and increases grain yield

“…[1][2][3][4][5] Large numbers of experiments involving exogenous application of melatonin to a series of plant species indicated that melatonin acts as a biostimulator in plants 6 by enhancing a myriad of defense responses against abiotic stresses, including oxidative stress, 7-10 high temperature, 10,11 cold, [12][13][14] senescence, 15,16 drought, 17,18 and salt, 19,20 as well as biotic stress such as pathogen attacks. [21][22][23][24][25][26][27][28][29] In addition to the defense responses, melatonin has also been implicated in promoting plant growth processes, such as seedling growth, 30,31 flowering, 32 nutrient absorption, 33 and fruit ripening, 34 suggesting a potential role of melatonin as a plant growth factor. 6 Recently, the relationship between melatonin and cadmium has been a focus of attention because melatonin treatment not only attenuated the toxic effects of cadmium stress in tomato and rice, but melatonin levels were shown to be upregulated in response to cadmium to such an extent that this heavy metal is the most effective elicitor of melatonin biosynthesis in plants.…”

Melatonin Increases the Chilling Tolerance of Chloroplast in Cucumber Seedlings by Regulating Photosynthetic Electron Flux and the Ascorbate-Glutathione Cycle

“…Melatonin itself is an effective antioxidant, which directly scavenges ROS and whose metabolite, N1 -acetyl- N2 -formyl-5-methoxykynuramine (AMFK), can also directly and efficiently scavenge ROS (Tan et al, 2007a; Manchester et al, 2015). Beyond this, melatonin also possesses antioxidant activity operating by stimulating antioxidant enzymes and augmenting antioxidants and involving the ascorbate–glutathione (AsA–GSH) cycle to scavenge excess ROS (Wang et al, 2012; Li et al, 2015; Chao et al, 2016). However, previous studies on the effects of melatonin on the AsA–GSH cycle under stress conditions are based mainly on whole leaves.…”