REVIEW | doi:10.20944/preprints202010.0051.v1
Subject: Biology, Anatomy & Morphology Keywords: melatonin; ROS; NO; posttranslational modifications (PMTs); abiotic stress; drought; salinity; high temperature; high light; waterlogging; abiotic stress combination
Online: 5 October 2020 (07:48:29 CEST)
Abiotic stress in plants is an increasingly common problem in agriculture, and thus, studies on plant treatments with specific certain compounds that may help to mitigate these effects have increased in recent years Melatonin (MET) application and its role in mitigating the negative effects of abiotic stress in plants have become important in the last few years. MET, a derivative of tryptophan, is an important plant-related response molecule involved in the growth, development, and reproduction of plants, and the induction of different stress factors. In addition, MET plays a protective role against different abiotic stresses such as salinity, high/low temperature, high light, waterlogging, nutrient deficiency and stress combination by regulating both the enzymatic and non-enzymatic antioxidant defense systems. Also, MET interacts with many signaling molecules, among these, reactive oxygen species (ROS) and nitric oxide (NO), and participates in a wide variety of physiological reactions. It is well known that NO produces S-nitrosylation and NO2-Tyr of important antioxidant-related proteins, being this an important mechanism for maintaining the antioxidant capacity of the AsA/GSH cycle under nitro-oxidative conditions, being extensively reviewed here under different abiotic stress conditions. Lastly, in this review, we show the coordination between NO and MET as a long-range signaling molecule, regulating many responses in plants, including plant growth and abiotic stress tolerance. Despite all the knowledge acquired over the years, there is still more to know about how MET and NO act on tolerance to abiotic stresses.
REVIEW | doi:10.20944/preprints202205.0279.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: Melatonin; NO; ROS; abiotic stress; NOmela; H2S; NRS; PTMs
Online: 20 May 2022 (13:35:00 CEST)
Melatonin (MEL), a ubiquitous indolamine, is a molecule whose regulatory role in plan metabolism has gained interest in the last decades. Likewise, nitric oxide (NO), a gasotransmitter, can also affect plant molecular pathways due to its function as a signalling molecule. Both MEL and NO can interact at multiple levels under abiotic stress, starting by their own biosynthetic pathways and inducing a particular signalling response in plants. This review summarizes the role of these molecules during plant development and fruit ripening, as well as their interactions. Due to the impact of climate change‐related abiotic stresses on agriculture, this review has also focused on their role in mediating abiotic stress tolerance and the mechanisms by which they operate, from upregulation of the whole antioxidant defence system to posttranductional modifications of important molecules. Their interactions and crosstalk with phytohormones and H2S is also discussed. Finally, we introduce NOmela, an emerging and very unknown molecule which seems to have a stronger potential than MEL and NO separately in mediating plant stress response.
REVIEW | doi:10.20944/preprints202104.0637.v1
Subject: Biology, Anatomy & Morphology Keywords: metal toxicity, phytomelatonin, heavy metals, ROS, NO
Online: 23 April 2021 (12:36:12 CEST)
Metal toxicity in soils, along with water runoff, are increasing environmental problems that affect agriculture directly and, in turn, human health. In light of finding a suitable and urgent solution, research on plant treatments with specific compounds that can help mitigate these effects has increased, and thus the exogenous application of melatonin (MET) and its role in alleviating the negative effects of metal toxicity in plants, have become more important in the last few years. MET is an important plant-related response molecule involved in growth, development, and reproduction, and in the induction of different stress-related key factors in plants. It has been shown that MET plays a protective role against the toxic effects induced by different metals (Pb, Cd, Cu, Zn, B, Al, V, Ni, La, As, and Cr) by regulating both the enzymatic and non-enzymatic antioxidant plant defense systems. In addition, MET interacts with many other signaling molecules, such as reactive oxygen species (ROS) and nitric oxide (NO), and participates in a wide variety of physiological reactions. Furthermore, MET treatment enhances osmoregulation and photosynthetic efficiency and increases the concentration of other important antioxidants such as phenolic compounds, flavonoids, polyamines (PAs), and carotenoid compounds. Some recent studies have shown that MET appeared to be involved in the regulation of metal transport in plants, and lastly, various studies have confirmed that MET significantly upregulated stress tolerance-related genes. Despite all the knowledge acquired over the years, there is still more to know about how MET is involved in the metal toxicity tolerance of plants.