metal(loid)s and non-metals within the plant are principally reliant on the type of
plant species, concentration of ions/molecules and their oxidation state (Tangahu
et al. 2011). Intrinsic protein, proton pumps and transporters (IRT1, ZnT1, heavy
metal ATPase-HMA2, and HMA4) facilitate the uptake and transportation of Zn,
Cu, Cd, Pb, Ni and Fe to various parts of the plant (Martinoia 2018; Viehweger
2014). Contaminants translocate from roots to shoot by two regulatory mechanism,
i.e. evaporation and transpiration (Tangahu et al. 2011). Plants are mainly of two
types: accumulators and excluders. Accumulators continue to be present in spite of
concerted pollutants in the shoots, whereas excluders confined pollutant phytouptake. Both accumulator and excluder manage to combat the high metal contents
in their body parts through adapted defence strategies (Viehweger 2014).
Organic and inorganic pollutants in soil beyond National Oceanic and Atmospheric Administration (NOAA) soil quality guidelines may cause deleterious
effects on plants (Buchmann 2008). They pose toxic effects on plant cell ultrastructure, biosynthesis, membrane stability and deoxyribonucleic acid (DNA) which
consequently affect their metabolic, photosynthetic and reproductive processes.
Organic and inorganic pollutants adversely affect the cellular ultrastructure such as
distortion of the cell wall, leakage of the cytoplasm and alteration in the shape and
size of chloroplasts from ovate to hexagonal (Xiong et al. 2017). Ramadass et al.
(2015) found that organic pollutants, for example, bipyridylium and diphenylether,
persuade cell membrane disruption and damage the plant tissues. Zhang et al. (2017)
unravel the adverse effects of organic pollutants on the assemblage of micro-tubulins
and associated proteins in the cell. Toxic effects of metal contents in plants may be
direct and/or indirect. Some of the direct toxic effects associated with high metal
contents include inhibition of cytoplasmic enzymes and damage to cell structures
due to oxidative stress (Jadia and Fulekar 2009), whereas indirect toxic effect is
composed of replacement of essential nutrients at cation exchange sites of plants
(Taiz and Zeiger 2002).
Several studies have reported the impact of pollutants (toxic metal(loid)s, PCBs,
antibiotics and herbicides) on plant cell biosynthesis, detrimental effects on photosynthesis and synthesis of proteins, amino acids, nucleic acids, lipids and hormones
(Zhang et al. 2017; Asati et al. 2016). Photosynthesis is an essential process in plants,
responsible for nutrient uptake, arbitrates growth as well as yield and provides
potential resistance to plants under environmental stresses (Yang et al. 2010).
Pollutants alter photosynthesis by hampering the formation of pigments causing
leaves and stems to become translucent and white (Kaspary et al. 2014). It has been
reported that ribonucleic acid (RNA), protein and lipid synthesis are significantly
inhibited by prolonged exposure to hexazinone and chlorsulfuron treatments (Yang
et al. 2010). Increase in malondialdehyde content is positively correlated with the
inhibition of antioxidative enzyme activities in some plants under oxidative stress
induced by organic and inorganic pollutants (Zhang et al. 2017; Gautam et al. 2016).
Some studies have revealed that DNA damage can be caused by metals (Cd, Cr and
Pb) and PAHs (Huang et al. 2013). A possible reason for this could be attributed to
alteration in protein synthesis, enzyme activities and cell organelle dysfunction,
which may result in inhibition of mitotic division in root tip cells (Van Dingenen
464
M. Gautam et al.
plant species, concentration of ions/molecules and their oxidation state (Tangahu
et al. 2011). Intrinsic protein, proton pumps and transporters (IRT1, ZnT1, heavy
metal ATPase-HMA2, and HMA4) facilitate the uptake and transportation of Zn,
Cu, Cd, Pb, Ni and Fe to various parts of the plant (Martinoia 2018; Viehweger
2014). Contaminants translocate from roots to shoot by two regulatory mechanism,
i.e. evaporation and transpiration (Tangahu et al. 2011). Plants are mainly of two
types: accumulators and excluders. Accumulators continue to be present in spite of
concerted pollutants in the shoots, whereas excluders confined pollutant phytouptake. Both accumulator and excluder manage to combat the high metal contents
in their body parts through adapted defence strategies (Viehweger 2014).
Organic and inorganic pollutants in soil beyond National Oceanic and Atmospheric Administration (NOAA) soil quality guidelines may cause deleterious
effects on plants (Buchmann 2008). They pose toxic effects on plant cell ultrastructure, biosynthesis, membrane stability and deoxyribonucleic acid (DNA) which
consequently affect their metabolic, photosynthetic and reproductive processes.
Organic and inorganic pollutants adversely affect the cellular ultrastructure such as
distortion of the cell wall, leakage of the cytoplasm and alteration in the shape and
size of chloroplasts from ovate to hexagonal (Xiong et al. 2017). Ramadass et al.
(2015) found that organic pollutants, for example, bipyridylium and diphenylether,
persuade cell membrane disruption and damage the plant tissues. Zhang et al. (2017)
unravel the adverse effects of organic pollutants on the assemblage of micro-tubulins
and associated proteins in the cell. Toxic effects of metal contents in plants may be
direct and/or indirect. Some of the direct toxic effects associated with high metal
contents include inhibition of cytoplasmic enzymes and damage to cell structures
due to oxidative stress (Jadia and Fulekar 2009), whereas indirect toxic effect is
composed of replacement of essential nutrients at cation exchange sites of plants
(Taiz and Zeiger 2002).
Several studies have reported the impact of pollutants (toxic metal(loid)s, PCBs,
antibiotics and herbicides) on plant cell biosynthesis, detrimental effects on photosynthesis and synthesis of proteins, amino acids, nucleic acids, lipids and hormones
(Zhang et al. 2017; Asati et al. 2016). Photosynthesis is an essential process in plants,
responsible for nutrient uptake, arbitrates growth as well as yield and provides
potential resistance to plants under environmental stresses (Yang et al. 2010).
Pollutants alter photosynthesis by hampering the formation of pigments causing
leaves and stems to become translucent and white (Kaspary et al. 2014). It has been
reported that ribonucleic acid (RNA), protein and lipid synthesis are significantly
inhibited by prolonged exposure to hexazinone and chlorsulfuron treatments (Yang
et al. 2010). Increase in malondialdehyde content is positively correlated with the
inhibition of antioxidative enzyme activities in some plants under oxidative stress
induced by organic and inorganic pollutants (Zhang et al. 2017; Gautam et al. 2016).
Some studies have revealed that DNA damage can be caused by metals (Cd, Cr and
Pb) and PAHs (Huang et al. 2013). A possible reason for this could be attributed to
alteration in protein synthesis, enzyme activities and cell organelle dysfunction,
which may result in inhibition of mitotic division in root tip cells (Van Dingenen
464
M. Gautam et al.