Changes in nitrate reductase activity and oxidative stress response in the moss Polytrichum commune subjected to chromium, copper and zinc phytotoxicity

Abstract

The main aim of this paper was to investigate the effect of chromium (Cr), copper (Cu) and zinc (Zn) on nitrate reductase (NR) activity and oxidative stress responses in the moss Polytrichum commune. Cr, Cu and Zn resulted in the inhibition of NR activity. A decline in total chlorophyll content was observed after 24 and 48 h of metal treatment. Accumulation of the metals showed a dose and time dependent increase. High accumulation of Cu, Cr and Zn were seen in moss shoots after 24 and 48 h of treatment. Treatment of Cr, Cu and Zn for 24 or 48 h resulted in the increase of malondialdehyde (MDA) content in moss shoots. The highest increase was observed in shoots under Cu treatment followed by Cr and Zn. The MDA content was significantly higher after 48h. Antioxidant enzymes viz., catalase (CAT), guaiacol peroxidase (GPx), glutathione reductase (GR) and superoxide dismutase (SOD) were affected by elevated concentrations of the three metals. Increase in the activity of CAT, GR and SOD was seen after 24 and 48 h of treatment. GPx activity declined under Cr treatment. However, under Cu and Zn, an increase in GPx was seen after 24 h and 48 h of treatment. For Zn, the antioxidant efficiency was less affected as compared to Cr and Cu. The response of Polytrichum commune to toxic concentrations of Cr, Cu and Zn appears to induce oxidative damage as observed by the increase in MDA content and antioxidant metabolism.

Effects of Different Zn Supply Levels on Physiological Parameters, Seed Zn Concentration and Root Cell Ultrastructure in three Different Genotypes of Brassica Species

“…When Zn level is higher than 10.0 mg kg -1 , MDA content shows an upward trend and reached up to the peak level at Zn supply level of 20.0 mg kg -1 . These results suggest that low Zn is benefit for the growth of plants; in contrast, excessive Zn can induce Zn stress and result in increasing MDA content and influencing the normal growth of plants and same trend was reported by Panda and Choudhury (2005).…”

Bryophytes and heavy metals: a review

“…The absence of a root system indicates the ability of these plants to absorb heavy metals over the entire surface (Berg andSteinnes 1997, Degola et al 2014). The lack of the cuticle layer, which makes their cell walls easy accessible for metal ions (Choudhury andPanda 2005, Koz andCevik 2014), pronounced ion-exchange properties (Little and Martin 1974) and a large surface-to-weight ratio also significantly contribute to this ability (Sun et al 2009). Consequently, they can react to and reflect the changes in the heavy metal concentrations faster than most vascular plants (Zvereva and Kozlov 2011).…”

“…These effects include ultrastructural changes as well as the changes in the plant physiological processes and characteristics (Sun et al 2009, Canivet et al 2015. Ultrastructural changes seen in bryophytes under heavy metal stress may include alternations of the chloroplast shape and thylakoid organization (Choudhury and Panda, 2005) as well as the appearance of the stromal plastoglobules in them (Basile et al 2009). In the moss Scorpiurum circinatum (Brid.)…”

“…Also, the phenomenon that some bryophytes tend to grow on substrates containing certain heavy metals led to their use as bioindicators that could imply the presence of a specific metal in that particular environment (Shaw 1987). Additionally, the relative simplicity of these plants (Markert andWeckert 1989, Reski 1998) makes them an important model for the investigation of morphological and genomic alterations in plants due to heavy metal toxicity (Carginale et al 2004, Choudhury andPanda 2005). Finally, the key phylogenetic position of bryophytes in plant evolution, connecting the terrestrial and aquatic mode of life (Shaw and Renzaglia 2004, Shaw et al 2011, Strotbek et al 2013, and the fact that they are the most conservative group of land plants (Reski 1998), emphasize their importance for the studies of the evolution of plant resistance mechanisms to this type of environmental pollution.…”

“…One of the potential reasons for the lack of control of nonessential metals input could be the absence of the specific transporters for these metals (Pérez-Llamazares et al 2011). Instead, they could be using channels and transporters of the plasma membrane that normally function in the uptake of essential ions (Wells et al 1995, Choudhury andPanda 2005), which leads to the increase of their intracellular concentration independently of the previously existent intracellular concentration (Choudhury and Panda 2005).…”