Melatonin redirects carbohydrates metabolism during sugar starvation in plant cells

Abstract

Recent studies have shown that melatonin is an important molecule in plant physiology. It seems that the most important is that melatonin efficacy eliminates oxidative stress (direct and indirect antioxidant) and moreover induce plant stress reaction and switch on different defence strategies (preventively and interventively actions). In this report, the impact of exogenous melatonin on carbohydrate metabolism in Nicotiana tabacum L. line Bright Yellow 2 (BY-2) suspension cells during sugar starvation was examined. We analysed starch concentration, α-amylase and PEPCK activity as well as proteolytic activity in culture media. It has been shown that BY-2 cell treatment with 200 nM of melatonin improved viability of sugar-starved cells. It was correlated with higher starch content and phosphoenolpyruvate carboxykinase (PEPCK) activity. The obtained results revealed that exogenous melatonin under specific conditions (stress) can play regulatory role in sugar metabolism, and it may modulate carbohydrate concentration in etiolated BY-2 cells. Moreover, our results confirmed the hypothesis that if the starch is synthesised even in sugar-starved cells, it is highly probable that melatonin shifts the BY-2 cell metabolism on gluconeogenesis pathway and allows for synthesis of carbohydrates from nonsugar precursors, that is amino acids. These points to another defence strategy that was induced by exogenous melatonin applied in plants to overcome adverse environmental conditions.

Nano-ZnO-Induced Drought Tolerance Is Associated with Melatonin Synthesis and Metabolism in Maize

“…Then serotonin is converted into melatonin by serotonin N-acetyltransferase (SNAT) and N-acetylserotonin O-methyltransferase (ASMT)/caffeic acid O-methyltransferase (COMT) [22]. Under stress conditions, the endogenous melatonin level normally increased through alterations in biosynthesis and metabolism pathways, to protect mitochondria and chloroplast against oxidative stress [23]. Once synthesized, melatonin is rapidly metabolized into 2-hydroxymelatonin (2-HM).…”

The Role of Melatonin in Salt Stress Responses

“…Subsequently, melatonin has been found in different plant species and in various organs, such as roots, stems, leaves, fruits, and seeds. In plants, melatonin functions as a metabolite with multiple functions, including the response to plant stresses such as salinity [28], cold [29], drought [30], reactive oxygen species (ROS) [31], and nutritional deficiency [32]; it also regulates growth and development, such as root organogenesis, flowering, and senescence [33,34,35,36,37]. In recent years, many studies have focused on the function and regulation of melatonin in plants adapted to salt stress.…”

Melatonin: A Multifunctional Factor in Plants

“…It is distributed in the leaves, stems, roots, fruits and seeds of various plants ( Table 1 ). It is not only associated with plant stress response, such as cold [ 17 ], salinity [ 18 ], drought [ 19 ], oxidative [ 20 ] and nutritional deficiency [ 21 ], but also relative to development regulation, such as growth [ 22 ], senescence [ 23 , 24 ], root organogenesis [ 25 ] and flowering [ 26 ].…”