Accumulation and tolerance of Cr and Pb using a cell suspension culture system of Jatropha curcas

Jatropha curcas has shown to be a bioaccu- mulator and a tolerant species to different heavy metals (HMs). This study presents an evaluation system for tol- erance and accumulation of chromium (Cr) and lead (Pb) in J. curcas using a cell suspension culture (CSC). This CSC was established with callus obtained from hypocotyls segments, onto Murashige-Skoog medium and 2.27 lM 2,4-dichlorophenoxyacetic acid (2,4-D). CSC growth kinetics showed a specific cell growth rate (l) of 0.092 d -1 and a doubling time of 7.5 d. Exposure of the CSC to HMs (Cr, or Pb at 0.0, 0.5, 1.0, 2.0 and 3.0 mM), resulted in a significant effect (P B 0.05) on biomass accumulation. By adding Cr (0.5 or 1.0 mM) or any Pb concentration, bio- mass was increased. Maximum biomass production (15.1 g L -1 ) was shown with Pb (3.0 mM), while all tol- erance index values were between 47.8 and 136 %. In addition, the maximum accumulation of Cr (6,368 mg kg -1 ) and Pb (8,608 mg kg -1 ) were found by adding the highest concentrations used of Cr or Pb (3 mM). Bioaccumulation factors (BF) were higher (29 and 41) in the high concentrations of 2.0 and 3.0 mM Cr, respec- tively. In contrast, maximum BF values of Pb (16.6 and 19.4) were observed when low concentrations of Pb were used (1.0 and 0.5 mM, respectively). This is the first study reporting HMs accumulation and tolerance in J. curcas CSC. Therefore, in further studies, this culture system may be used as a model to explore the cellular mechanisms used for tolerance and accumulation of HMs.