Abstract:
Zinc oxide (ZnO) and Titanium dioxide(TiO2) nanoparticles (NPs) are
released into the environment and pose serious risks to plants. Impact of these
NPs on edible food crops, which is a point of entry of NPs into the food chain, is
very little documented. In the present study, we aimed to identify Glutathione S
transferase (GST) genes from Lactuca sativa (lettuce) genome and check their
response against nanotoxicity imposed by ZnO and TiO2 NPs. Translocation of
the NPs in lettuce was confirmed through X-ray Diffraction (XRD) and Scanning
Electron Microscopy (SEM) analysis. In silico analysis revealed the presence of
113 putative GST genes in lettuce from Compositae genome project database,
GenomeNET and DDBJ/EMBL/GenBank sequence database; that were divided
into 5 classes through phylogenetic analysis. Quantitative real time PCR was used
to monitor the changes in expression ofTC18793 gene of phi class, TC20111 and
TC20660 genes of tau class in ZnO and TiO2 treated plants. Expression of
TC18793, TC20111 and TC20660 genes was upregulated by 39.2, 4.7 and 5.7
fold respectively in ZnO NP treated plants while TC18793, TC20111 and
TC20660 genes was upregulated by 0.79, 17.90 and 0.94 fold in TiO2 NP treated
plants. GST specific enzyme activity was also significantly increased (p<0.05) in
ZnO and TiO2 treated plants. Our results indicate that TiO2.and ZnO NPs may
cause the phytotoxicity in lettuce.
