Biological Responses to Cadmium Stress in Liverwort Conocephalum conicum (Marchantiales).

Viviana Maresca,Marina Piscopo,Gennaro Lettieri,Sergio Sorbo,Adriana Basile

doi:10.3390/ijms21186485

Abstract

Oxidative damage (production and localization of reactive oxygen species) and related response mechanisms (activity of antioxidant enzymes), and induction of Heat Shock Protein 70 expression, have been studied in the toxi-tolerant liverwort Conocephalum conicum (Marchantiales) in response to cadmium stress using two concentrations (36 and 360 µM CdCl2). Cadmium dose-dependent production of reactive oxygen species (ROS) and related activity of antioxidant enzymes was observed. The expression level of heat shock protein (Hsp)70, instead, was higher at 36 µM CdCl2 in comparison with the value obtained after exposure to 360 µM CdCl2, suggesting a possible inhibition of the expression of this stress gene at higher cadmium exposure doses. Biological responses were related to cadmium bioaccumulation. Since C. conicum was able to respond to cadmium stress by modifying biological parameters, we discuss the data considering the possibility of using these biological changes as biomarkers of cadmium pollution.

Highlights

The contamination of aquatic and terrestrial ecosystems with heavy metals is an environmental problem of public health concern [1]
reactive oxygen species (ROS)-conjugates signals were emitted from the cytoplasm, the most metabolically active compartment of the cell, while the red light came from chloroplasts
After 2 -7 dichlorofluorescein diacetate (DFC-DA) has entered the cell, it undergoes modification into DCF, which is trapped in the cytoplasm and, after reaction with ROS, can be detected as fluorescent DCF-derived compound [27]

Summary

Introduction

The contamination of aquatic and terrestrial ecosystems with heavy metals is an environmental problem of public health concern [1]. Cadmium (Cd) is a toxic non-essential transition metal; the third main environmental contaminant of most hazards after mercury and lead. This metal poses a health risk for both humans and animals already at very low concentrations (0.5 μM) [2,3,4,5], while for plants there is usually a wider range of concentrations (from 5 to 5000 μM) that are generally not phytotoxic to the plants [6,7]. Cd can negatively affect plant growth, and its toxic effects can be found at both morphological and physiological levels [8]. Effects are known at the cellular level [10]. The effects of cadmium generally occur with an alteration of photosynthesis and respiration, mineral absorption and alterations in gene expression [12,13]

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