442:	Uptake of heavy metals and phytochelatin synthesis in fibre hemp (Cannabis sativa L.).

Authors:	Ostwald, Anke(A)Goldsbrough, Peter(B)Theimer, Roland, R.(A)
Affiliations:	(A): Bergische Universitaet Wuppertal (B): Purdue University
Presenter:	Ostwald, Anke , ostwald@uni-wuppertal.de

Low THC hemp (Cannabis sativa L.) is a supplier of high quality natural products such as oil, protein, and fibres. Also hemp has a high ability for the uptake of heavy metals (Cd, Pb, U) from polluted soils.Therefore hemp could be a good phytoremediation crop like Brassica juncea. After 10 days of germination on soils contaminated with 10 mM Cd or Pb high amounts of Cd and Pb (1 mg/g dw) were found in the roots of hemp. In stems and leaves only low amounts of heavy metals were detected. In most cases tolerance of higher plants against heavy metals is achieved by synthesis of SH-rich peptides, i.e. phytochelatins ((g-Glu-Cys)n-Gly). Exposure to Cd leads to the accumulation of SH-rich peptides in the roots of hemp plants. HPLC elution profiles of stems and leaves showed the accumulation of the same SH-rich peptides but in much lower concentrations. In contrast, exposure to Pb or Cu does not induce the synthesis of these peptides. Hemp seedlings grown for 6 days in unpolluted soils showed a distinct decrease of the GSH level in the roots 10 min after addition of 10 mM Cd. One hour after contamination the GSH level reaches a minimum but then increases until the original level is reached again. Small peaks of SH-rich peptides were detected in hemp roots within the first hour after treatment with Cd. The peptide profiles of Cd contaminated hemp plants, hemp cell suspension cultures, and hemp callus cultures show comparable peak patterns. The dominant peaks (9, 11, 14 min retention time) can be found in all three systems. MS analysis proves that the dominant peaks are the phytochelatins PC2, PC3, and PC4.Some other SH-rich peptides detected by HPLC in root extracts are still being characterized by amino acid analysis and MS.