The Moss <i>Leptodictyum riparium</i> Counteracts Severe Cadmium Stress by Activation of Glutathione Transferase and Phytochelatin Synthase, but Slightly by Phytochelatins

oleh: Erika Bellini, Viviana Maresca, Camilla Betti, Monica Ruffini Castiglione, Debora Fontanini, Antonella Capocchi, Carlo Sorce, Marco Borsò, Laura Bruno, Sergio Sorbo, Adriana Basile, Luigi Sanità di Toppi

Format: Article
Diterbitkan: MDPI AG 2020-02-01

Deskripsi

In the present work, we investigated the response to Cd in <i>Leptodictyum riparium</i>, a cosmopolitan moss (Bryophyta) that can accumulate higher amounts of metals than other plants, even angiosperms, with absence or slight apparent damage. High-performance liquid chromatography followed by electrospray ionization tandem mass spectrometry of extracts from <i>L. riparium</i> gametophytes, exposed to 0, 36 and 360 &#181;M Cd for 7 days, revealed the presence of &#947;-glutamylcysteine (&#947;-EC), reduced glutathione (GSH), and traces of phytochelatins. The increase in Cd concentrations progressively augmented reactive oxygen species levels, with activation of both antioxidant (catalase and superoxide dismutase) and detoxifying (glutathione-<i>S-</i>transferase) enzymes. After Cd treatment, cytosolic and vacuolar localization of thiol peptides was performed by means of the fluorescent dye monochlorobimane and subsequent observation with confocal laser scanning microscopy. The cytosolic fluorescence observed with the highest Cd concentrations was also consistent with the formation of &#947;-EC-bimane in the cytosol, possibly catalyzed by the peptidase activity of the <i>L. riparium</i> phytochelatin synthase. On the whole, activation of phytochelatin synthase and glutathione-<i>S</i>-transferase, but minimally phytochelatin synthesis, play a role to counteract Cd toxicity in <i>L. riparium</i>, in this manner minimizing the cellular damage caused by the metal. This study strengthens previous investigations on the <i>L. riparium</i> ability to efficiently hinder metal pollution, hinting at a potential use for biomonitoring and phytoremediation purposes.