271
to C 70 NPs than MWCNTs (Lin et al. 2009a). SWCNTs were found to alter the
expression of genes associated with seminal root and root hair growth of maize.
SWCNTs induced upregulation of genes encoding epigenetic modification enzymes,
causing deacetylation of H3 histones that affected root growth (Yan et al. 2013).
Magnetic NP exposure has increased the mitotic index and induced low percentage heritable chromosomal aberrations to maize plants (Racuciu and Creanga
2009a). Ag NPs have been reported to interact with pollen membranes and reduce
their viability in kiwi. These NPs were more potent at disrupting the pollen tube
elongation process by inducing ultrastructural alterations and changing their calcium content (pollen tube elongation is a critical step of fertilization in flowering
plants. Exposure of PVP-coated Ag NPs induced the disruption of pollen tube elongation in kiwi fruits. This disruption has lowered their ability to reproduce)
(Speranza et al. 2013). Perchloric acid-coated Fe oxide NPs were documented to
stimulate nucleic acid biosynthesis and reduce chlorophyll a/ chlorophyll b ratio
and plant length in maize. The magnetic NPs were internalized by vegetal tissue and
they absorbed electromagnetic energy. This induced putative local heating, leading
to the observed metabolic process–mediated regeneration reactions (Racuciu et al.
2009). TiO 2 NPs were, likewise, found to reduce the mitotic index of V. narbonensis
and maize plants. Disturbances induced in spindle apparatus, DNA strand breakage,
and chromosomal aberrations were responsible for the reduction of plant mitotic
index (Castiglione et al. 2011).
Ag NPs have induced genotoxic effects as a result of bridging of chromatin,
disturbed metaphase, and multiple chromosomal breaks in A. cepa root cells
(Kumari et al. 2009). CdS QD-treated A. thaliana showed the upregulation of 195
and downregulation of 43 genes. Among these genes, 32% of genes were involved
in stress tolerance. Transgenic A. thaliana containing Ds elements confirmed that
the Ds insertion site was responsible for countering QD toxicity (Marmiroli
et al. 2014).
TiO 2 NP exposure was inducing DNA damage in V. narbonensis plants. TiO 2
NPs did not induce H 2 O 2 and ROS production, so ROS-independent DNA fragmentation mechanism was involved in TiO 2 -mediated genotoxic effects. TiO 2 was found
to interact directly with the phosphate groups of DNA and inducing damage
(Castiglione et al. 2014). Graphene induced an increase in the expression of genes
encoding water channel proteins in barley, corn, and soybean plants. These genes
have induced more uptake of graphene through the water channels and hence
enhanced the phytotoxic effects (Lahiani et al. 2013).
NPs Negatively Altered Plant Growth by Inducing Oxidative/Abiotic Stress
SWCNTs have induced oxidative stress in the leaves and protoplast of A. thaliana
and rice cells. Oxidative stress was responsible for the initiation of programmed cell
death in A. thaliana and rice plants (Shen et al. 2010). TiO 2 NPs have been reported
to induce disorganization of microtubular and 26S proteosome-mediated tubulin
degradation in A. thaliana root cells. ROS generation and physical interaction with
10 Phytoresponse to Nanoparticle Exposure
to C 70 NPs than MWCNTs (Lin et al. 2009a). SWCNTs were found to alter the
expression of genes associated with seminal root and root hair growth of maize.
SWCNTs induced upregulation of genes encoding epigenetic modification enzymes,
causing deacetylation of H3 histones that affected root growth (Yan et al. 2013).
Magnetic NP exposure has increased the mitotic index and induced low percentage heritable chromosomal aberrations to maize plants (Racuciu and Creanga
2009a). Ag NPs have been reported to interact with pollen membranes and reduce
their viability in kiwi. These NPs were more potent at disrupting the pollen tube
elongation process by inducing ultrastructural alterations and changing their calcium content (pollen tube elongation is a critical step of fertilization in flowering
plants. Exposure of PVP-coated Ag NPs induced the disruption of pollen tube elongation in kiwi fruits. This disruption has lowered their ability to reproduce)
(Speranza et al. 2013). Perchloric acid-coated Fe oxide NPs were documented to
stimulate nucleic acid biosynthesis and reduce chlorophyll a/ chlorophyll b ratio
and plant length in maize. The magnetic NPs were internalized by vegetal tissue and
they absorbed electromagnetic energy. This induced putative local heating, leading
to the observed metabolic process–mediated regeneration reactions (Racuciu et al.
2009). TiO 2 NPs were, likewise, found to reduce the mitotic index of V. narbonensis
and maize plants. Disturbances induced in spindle apparatus, DNA strand breakage,
and chromosomal aberrations were responsible for the reduction of plant mitotic
index (Castiglione et al. 2011).
Ag NPs have induced genotoxic effects as a result of bridging of chromatin,
disturbed metaphase, and multiple chromosomal breaks in A. cepa root cells
(Kumari et al. 2009). CdS QD-treated A. thaliana showed the upregulation of 195
and downregulation of 43 genes. Among these genes, 32% of genes were involved
in stress tolerance. Transgenic A. thaliana containing Ds elements confirmed that
the Ds insertion site was responsible for countering QD toxicity (Marmiroli
et al. 2014).
TiO 2 NP exposure was inducing DNA damage in V. narbonensis plants. TiO 2
NPs did not induce H 2 O 2 and ROS production, so ROS-independent DNA fragmentation mechanism was involved in TiO 2 -mediated genotoxic effects. TiO 2 was found
to interact directly with the phosphate groups of DNA and inducing damage
(Castiglione et al. 2014). Graphene induced an increase in the expression of genes
encoding water channel proteins in barley, corn, and soybean plants. These genes
have induced more uptake of graphene through the water channels and hence
enhanced the phytotoxic effects (Lahiani et al. 2013).
NPs Negatively Altered Plant Growth by Inducing Oxidative/Abiotic Stress
SWCNTs have induced oxidative stress in the leaves and protoplast of A. thaliana
and rice cells. Oxidative stress was responsible for the initiation of programmed cell
death in A. thaliana and rice plants (Shen et al. 2010). TiO 2 NPs have been reported
to induce disorganization of microtubular and 26S proteosome-mediated tubulin
degradation in A. thaliana root cells. ROS generation and physical interaction with
10 Phytoresponse to Nanoparticle Exposure