Assessment of aquatic plants and expression profiling of potential genes involved in arsenic phytoremediation

Despite comprehensive usage in industries, Arsenic (As) contamination has resulted in greater health effects for the public. Among various technologies used to clean up these contaminants, phytoremediation is chosen as an alternative and cost-effective method where plants are used as remediating agents. This project aimed to screen aquatic plants that can tolerate As and profile selected plant genes expression involved in the As uptake. Six plants including Pontederia crassipes, Salvinia molesta, Epiprenum aureum, Neptunia oleracea, Nymphoides indica, and Limnocharis flava, were exposed to varying concentrations of As for 14 days for preliminary screening. After selection, the plants were exposed to the same treatment but with a higher range of As concentrations. All biochemical reactions were measured, and total arsenic uptake in all plants’ parts was determined. Total RNA of control and treated samples was isolated, converted, and reverse-transcribed and all products were analysed. The studies showed that N. oleracea, S. molesta and P. crassipes plants were capable of tolerating different concentrations of As. Therefore, they were selected for further studies on their biochemical reaction under As treatment. However, only P. crassipes had been shown to accumulate As in all of the plants’ parts with the highest accumulation were measured with 2.08 mg/L, 1.57 mg/L and 0.90 mg/L at 80 ppm of As concentrations in roots, leaves and stems, respectively. The Reverse-Transcription PCR analyses showed that the targeted genes, Heat shock protein (Hsp90) in both control and treated samples were highly expressed on Day 1 with 11.25 % and 8.40 %, respectively, but later decreased on Day 2 by 3.03-fold and 1.32-fold, respectively. As for the Heat shock protein 70 (Hsp70), the gene in both control and treated samples expressed more on Day 2 with 1.73 % and 4.95 %, respectively, compared to Day 1. On Day 3 of the treatment, both genes in treated samples barely showed any expression compared to control samples, but both genes’ expressions in control samples were reduced by the end of the treatment. In conclusion, phytoremediation using hyperaccumulator P. crassipes could uptake As at high concentrations ranging from 30 - 100 ppm and accumulate them at different plant tissues. Therefore, the data obtained from this study can further utilize this species in remediating As in contaminated water.

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