Heavy Metal Tolerance in Plants:

Overview

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Key numbers

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• Samiksha Singh 1 , Parul Parihar 1 , Rachana Singh 1 , Vijay P. Singh 2* and Sheo M. Prasad 1*
• Plant Physiology, which causes toxicity to the living organisms (Eapen and D’Souza, 2005; Kavamura and Esposito,
• a section of the journal 2010; Miransari, 2011). Large areas of land have been contaminated with heavy metals due to
• Received: 14 August 2015 release from smelting industries and metalliferous mines (Yang et al., 2005). Although many
• Accepted: 02 December 2015 heavy metals occur naturally in the earth’s crust at various levels, the problem arises when they
• Published: 08 February 2016 are released in excess into the environment due to natural and/or anthropogenic activities. The
• Citation: 53 elements belonging to the d-block have been categorized as “heavy metals” based on their
• Singh S, Parihar P, Singh R, Singh VP density (>5 g/cm3 ) (Jarup, 2003). During evolution of angiosperms, only 19 elements such as C,
• and Prasad SM (2016) Heavy Metal
• (micronutrients) were selected for basic metabolism (Ernst, 2006). In addition, Si is also considered
• Front. Plant Sci. 6:1143. structures in some plants (Epstein, 1999). Macro and micronutrients play an important role in
• doi: 10.3389/fpls.2015.01143 physiological and biochemical processes of plants such as chlorophyll biosynthesis, photosynthesis,
• chloroplast and the mitochondrion, sugar metabolism, and of heavy metal tolerance (Figure 1).
• 300 enzymes and 200 transcription factors associated with the
• Briat et al., 2007; Williams and Pittman, 2010; Prasad, 2012;
• Ricachenevsky et al., 2013). However, at elevated concentrations,
• the plant cells (Janicka-Russak et al., 2008; Saito et al., 2010;
• Singh et al., 2012; Srivastava et al., 2012; DalCorso et al., 2013a;
• Farias et al., 2013; Fidalgo et al., 2013). Some heavy metals,
• low concentrations (Ernst et al., 2008; Janicka-Russak et al.,
• 2008; Garzón et al., 2011; Hayat et al., 2012; Shahid et al., 2012;
• Chong-qing et al., 2013; Gill et al., 2013). Essential and non-
• its concentration high for as long as 150 years (NandaKumar
• et al., 1995; Yang et al., 2005). Plants growing in heavy metal-
• cancers (McLaughlin et al., 1999). This problem might become
• crop yield reduction of ca. 70%, and thus, are considered a
• great constraint to crop production (Acquaah, 2007; Jewell et al.,
• 2010). This situation has worsened due to disturbed equilibrium
• and desired agronomical traits (Lee et al., 2007; Atkinson and FIGURE 1 | Integrated approach to study plant responses to heavy
• Urwin, 2012). In this context, this review is focused on several metal stress. Transcriptomics, proteomics, metabolomics, and ionomics are
• after plants’ exposure to stress. For instance, Tamás et al. (2010) of primary root elongation. Similarly, Petö et al. (2011) have
• to Cd and Hg. Similar to this, Hernandez et al. (2012) reported that inhibition in root growth is accompanied by an increase in
• signs of sensing and signal transduction after exposure to heavy a target of heavy metal toxicity (Zobel et al., 2007). Therefore,
• metals. In another study by Zhang et al. (2002), seed germination these studies suggest that heavy metals might cause an inhibition
• high concentration of As. Similarly, Imran et al. (2013) reported thereby affecting their transportation to the aboveground
• nutrient balance and protein metabolism (Li et al., 2006; Singh anatomy. Apart from barricading the entry of heavy metals, roots
• et al., 2009; Ahsan et al., 2010). also allow their transportation to aboveground plant parts (in
• mechanisms. These include (i) similarities with the nutrient can grow in heavy metal-contaminated soil; Fahr et al., 2013) for
• damages the macromolecules (Sharma and Dietz, 2009; DalCorso rapid membrane voltage changes might be an excellent tool
• et al., 2013a). for monitoring the effects of heavy metal toxicity (Kenderešová
• The roots of sessile plants are the first organ that encounters et al., 2012). Once inside the cell, heavy metals alter metabolism
• the impact of a stressor. Plants growing on heavy metal-rich accumulation (Nagajyoti et al., 2010). Heavy metal toxicity

Methods (brief)

• Yuan et al. (2013) have reported that excess Cu affects both Elodea densa. Similarly, Li et al. (2012) have also reported that
• and 2DE samples. Among them, 18 protein spots were alterations under Cu stress due
• leaves by two-dimensional gel electrophoresis coupled with mass spectrometry. et al. (2010). Arabidopsis thaliana transcription factors bZIP19 and bZIP23
• Li, Y., Dhankher, O. P., Carreira, L., Lee, D., Chen, A., Schroeder, J. I., et al. and antioxidant status of elodea. Russ. J. Plant Physiol. 59, 190–197. doi:
• Shanker, K., Mishra, S., Srivastava, S., Srivastava, R., Daas, S., Prakash, S., et al. Singh, R. K., Anandhan, S., Singh, S., Patade, V. Y., Ahmed, Z., and Pande, V.

Implications

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Wiki pages this source may touch

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• Mercury
• Cadmium
• Lead
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• Nickel
• Aluminum
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Verification notes

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Update history

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