Exogenous melatonin expediently modifies proteome of maize (Zea mays L.) embryo during seed germination

Abstract

Melatonin (N-acetyl-5-methoxytryptamine) has a great potential for plant biostimulation. Its role in plant physiology is intensively explored, and its important function in plant stress defence frequently underlined. Melatonin is particularly effective when applied as an additional factor of seed priming. In the presented research, hydroconditioning was chosen experimentally as optimal for maize (Zea mays L.) seeds. The following seed variants were compared: controlled non-treated, hydroprimed with water and hydroprimed with melatonin solutions 50 and 500 lM. To identify modifications in proteome of maize seeds caused by the applied hydroconditioning techniques, protein extracts of germinated seed embryos (24 h, 25°C) were separated by 2D-PAGE. Next, obtained maps of proteomes were compared (statistically and graphically) using PDQuest software, and characteristic spots of proteins were analysed qualitatively by mass-spectrometric techniques and identified in the Mascot protein databases. Research helped to identify hydropriming-associated proteins, and for the first time those which were expressed only in the presence of melatonin. Study confirmed that suitably selected pre-sowing treatment with melatonin, by embryo proteome modification, effectively prepares plants to adverse environmental conditions. In melatonin treated seeds during the initial state of embryos growth, even under optimal conditions, additional antioxidative, detoxifying, anti-stresses proteins were synthesized. Moreover, the supply of energy from seed storage substances was pretty intensified. The presented results partially explain how melatonin acts in plant stress defence, and why plants with higher melatonin content have exhibited increased capacity for stress tolerance.

Melatonin Improves the Photosynthetic Apparatus in Pea Leaves Stressed by Paraquat via Chlorophyll Breakdown Regulation and Its Accelerated de novo Synthesis

“…It is also worth mentioning that transcriptome analysis of melatonin-treated Arabidopsis (Weeda et al, 2014 ) revealed upregulation of numerous genes implicated in the signaling of senescence-promotion but also stress-induced phytohormones, such as ethylene, abscisic, jasmonic, and salicylic acids (Jibran et al, 2013 ; Khan et al, 2014 ). This also might indicate that MEL provokes a stress response syndrome in plants as suggested by Kołodziejczyk et al ( 2016a , b ), although this issue still requires clarification. Since the breakdown of the damaged Chl and de novo synthesis are a natural processes occurring in plant cells, the next step was to examine if under oxidative stress MEL affects the contents of its precursor-ALA. Biosynthesis of ALA is the first step of Chl biosynthesis, and is therefore supposed to be a crucial control point in the regulation of Chl supply (Figure 2 ; Tanaka and Tanaka, 2006 ).…”

Direct visualization of location and uptake of applied melatonin and serotonin in living tissues and their redistribution in plants in response to thermal stress

“…One of the leading theories for the function of melatonin in mitigating diverse stresses, including thermal stress, is that it reduces ROS and free radicals produced in response to these stresses either directly or via upregulation of other related pathways, such as the ascorbate‐glutathione cycle, though many other mechanisms have also been identified such as interaction with phytohormone networks, or modification of protective transcription factors . Melatonin applied to seeds also modifies their proteome when germinated under optimal (prevention) and chilling stress (intervention) conditions . If melatonin is effective in combatting stress in this way, it would need to be present in cells under stress.…”

Melatonin Application to Pisum sativum L. Seeds Positively Influences the Function of the Photosynthetic Apparatus in Growing Seedlings during Paraquat-Induced Oxidative Stress

“…There are suggestions that seed conditioning may be a method of improving tolerance through ‘priming memory’ (Savvides et al, 2016). Generally it is provoked by induction of stress reaction syndrome without negative metabolic disorders and injuries, e.g., through epigenetic modifications and/or synthesis of corresponding anti-stress proteins (Kołodziejczyk et al, 2016a,b). …”