Lecturer University of Ibadan, Ibadan, Nigeria IBADAN, Oyo, Nigeria
Body of Abstract: Soil contamination with heavy metals is a life-threatening environmental stress. The use of native and tolerant plants for effective phytoremediation is being promoted. Two studies were carried out to assess the Pb hyperaccumulating potential of tolerant native plant species growing on Pb contaminated site and to identify the genes for Pb tolerance. Among these plant species in the first study, G. celosoides was found to be an hyperaccumulator and was able to tolerate Pb concentration of up to 4000 mg/kg for two weeks. It also accumulated up to 15149.8 mg kg-1Pb in the shoot and this was more than those of other species. For the Pb tolerance gene identification, two types of G. celosoides were used for the study. They are; G. celosoides growing on the Pb contaminated site and the other one from uncontaminated site (Control). These are exposed to Pb using in-vitro study and samples taken at one week after exposure. Different genes that have been reported for Pb tolerance were tested using RT-qPCR technique. These genes include; PDR8, PDR12, PCS2, PSE1 and CNCG10. Different primers were designed and used for amplification, while ACTIN 2 served as housekeeping gene. Among the tested genes, PSC2 was highly expressed in the treated plants with 2 folds increase and the expression in the G. celosoides from contaminated site was more than that from uncontaminated site. It could be concluded that G. celosoides is an hyperaccumulator and it makes use of phytochelatin as a strong metabolite for tolerance as reflected in the increase in the expression of phytochelatin synthase enzyme.