Symbiotic Role of Glomus Mosseae in Lead Phytoextraction Using Vetiver Grass

Phytoextraction of lead (Pb) from contaminated soils can be a promising remediation technology, particularly for cleanup of residential soils contaminated with lead-based paints. For successful Pb phytoremediation, the candidate species needs to be a high biomass plants that can accumulate large amounts of Pb in roots and transfer them to shoots. Vetiver grass (Vetiveria zizanioides) has shown the ability to accumulate high amount of Pb in varying soil and climatic conditions. However, soil Pb needs to be in a form that vetiver root can uptake, which may be a problem in soils where Pb precipitates as carbonate solids. In this study, we investigated the potential of arbuscular mycorrhizal (AM) fungus, Glomus mosseae (Gm) in increasing Pb uptake in vetiver grass. We conducted an incubation chamber pot experiment with four levels of Pb (0, 400, 800 and 1200 mg/kg) with and without vetiver grass colonized by communities of AM fungi. After 4 weeks of growth, the plants were harvested and total root and shoot biomass were measured. We analyzed Pb concentrations in the roots and the shoots in addition to analyzing for chlorophyll activity and the concentrations of low molecular weight thiols (LMWT). We found that the vetiver plants colonized by AM fungi not only tolerated higher concentrations of Pb compared to their non-infected counterparts, but their presence increased root and shoot dry mass as well at all application rates. Furthermore, the presence of AM fungi significantly increased Pb uptake by roots and also facilitated Pb translocation to shoots. We also found that the plants infected with AM fungi had higher chlorophyll activities and lower metal stress as indicated by the concentrations of LMWT. Results from this preliminary study indicate that AM fungi assisted phytoextraction of Pb by vetiver grass may have the potential to develop into an effective phytoremediation technology.