IDENTIFICATION OF COPPER-INDUCIBLE GENES IN Pistia stratiotes

IDENTIFICATION OF COPPER-INDUCIBLE GENES IN Pistia stratiotes
ABSTRACT
In this study, a widely used plant to investigate freshwater pollution, Pistia
stratiotes was utilized as a model system to determine the rate of copper uptake
and to identify the candidate gene(s) that was specifically induced in response to
copper challenge. The plant was exposed to various concentrations of copper (0,
1, 5, 10, 25, 50, 75, 100, 150 and 250 µg/ml) for 24 hours. Generally, it was
found that the amount of copper absorbed by Pistia stratiotes increased as the
concentrations of the heavy metal exposed to the plant increased. Interestingly,
the content of copper uptake by root was higher than to that of shoot. ACP-based
RT-PCR method was used to identify copper-inducible genes. Three copper-
inducible candidate gene fragments were identified and were found to be up-
regulated in Pistia stratiotes exposed to copper in dose- and time-dependent
manner. These findings strongly indicate that all three identified genes were
positively induced in copper-treated Pistia stratiotes. Using RLM-RACE, a full
length copper-inducible gene of fragment 1 was successfully cloned. Sequence
analysis revealed that the full length gene shared 56% and 71% identity at
nucleotide and amino acid levels, respectively, with Elaeis guineensis asparagine
synthase-related protein.
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