Bioremediation and Phytoremediation of Pesticides: Recent Advances

Glutathione S-transferases (GSTs) are abundant proteins encoded by a highly divergent, ancient gene family. Soluble GSTs form dimers, each subunit of which contains active sites that bind glutathione and hydrophobic ligands. Plant GSTs attach glutathione to electrophilic xenobiotics, which tags them for vacuolar sequestration. The role of GSTs in metabolism is unclear, although their complex regulation by environmental stimuli implies that they have important protective functions. Recent studies show that GSTs catalyse glutathione-depend-ent isomerizations and the reduction of toxic organic hydroperoxides. GSTs might also have non-catalytic roles as carriers for phytochemicals.

Data mining methods have been used to identify 356 Cyt P450 genes and 99 related pseudogenes in the rice (Oryza sativa) genome using sequence information available from both the indica and japonica strains. Because neither of these genomes is completely available, some genes have been identified in only one strain, and 28 genes remain incomplete. Comparison of these rice genes with the 246 P450 genes and 26 pseudogenes in the Arabidopsis genome has indicated that most of the known plant P450 families existed before the monocot-dicot divergence that occurred approximately 200 million years ago. Comparative analysis of P450s in the Pinus expressed sequence tag collections has identified P450 families that predated the separation of gymnosperms and flowering plants. Complete mapping of all available plant P450s onto the Deep Green consensus plant phylogeny highlights certain lineage-specific families maintained (CYP80 in Ranunculales) and lineage-specific families lost (CYP92 in Arabidopsis) in the course of evolution.