Melatonin Protects Tobacco Suspension Cells against Pb-Induced Mitochondrial Dysfunction.

Agnieszka Kobylińska,Małgorzata Maria Posmyk

doi:10.3390/ijms222413368

Agnieszka Kobylińska, Małgorzata Maria Posmyk

Open Access

https://doi.org/10.3390/ijms222413368

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Abstract

Recent studies have shown that melatonin is an important molecule in plant physiology. It seems that the most important is that melatonin effectively eliminates oxidative stress (direct and indirect antioxidant) and switches on different defence strategies (preventive and interventive actions) during environmental stresses. In the presented report, exogenous melatonin potential to protect Nicotiana tabacum L. line Bright Yellow 2 (BY-2) exposed to lead against death was examined. Analyses of cell proliferation and viability, the level of intracellular calcium, changes in mitochondrial membrane potential (ΔΨm) as well as possible translocation of cytochrome c from mitochondria to cytosol and subsequent caspase-like proteolytic activity were conducted. Our results indicate that pretreatment BY-2 with melatonin protected tobacco cells against mitochondrial dysfunction and caspase-like activation caused by lead. The findings suggest the possible role of this indoleamine in the molecular mechanism of mitochondria, safeguarding against potential collapse and cytochrome c release. Thus, it seems that applied melatonin acted as an effective factor, promoting survival and increasing plant tolerance to lead.

Highlights

Among the most significant soil contaminants resulting from both natural and manmade sources, heavy metals, and especially lead, are of prime importance due to their long-term toxicity effects [1])
We demonstrated that significant increases in cells viability and beneficial effects of exogenous melatonin on Pb-exposed Bright Yellow 2 (BY-2) cells are correlated with drastically decreasing in O2 - and H2 O2 contents and with changes in the expression of BI-1 protein—an ancient regulator of plant cell death
We found the inhibition of LEHDase activity in cells incubated with melatonin and treated with lead 24 and 72 h after heavy metal incubation, and for MEL + Pb samples, caspase-9-like pro(MEL + Pb)

Summary

Introduction

Among the most significant soil contaminants resulting from both natural and manmade sources, heavy metals, and especially lead, are of prime importance due to their long-term toxicity effects [1]). Lead (Pb) can be found in dust, fumes, mists, vapours and in soil as minerals (PbCO3 —cerussite, PbS—galena, PbSO4 —anglesite) [1]. Lead is taken up via roots, along with water, or it can be absorbed from the air via shoots and foliage [2]. Plant roots are not highly selective and absorb excessively accumulated lead. It affects mineral uptake, inducing imbalances in essential and trace elements resulted from toxic ion competitions with macro- and microelements and their replacement in various biologically active substances [3,4]. The decrease of P, K, Ca, Cu, Fe, Mn and Zn content in plant tissue, as a result of a possible blockage of the transporter proteins by lead, is observed [2,3,5]

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