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(W/EH051) IN VITRO VERSUS IN SITU CULTURES TO ASSAY CADMIUM EFFECT ON PROLINE CONTENT AND METABOLISM IN SUNFLOWER. gomes, clara 1, costa, armando1, santos, conceição1, 1 ABSTRACT- IN VITRO VERSUS IN SITU CULTURES TO ASSAY CADMIUM EFFECT ON PROLINE CONTENT AND METABOLISM IN SUNFLOWER Clara Gomes, Armando Costa and Conceicao Santos Department of Biology, University of Aveiro 3810 Aveiro Portugal Although the toxicity of Cd to vascular plants growing on hydroponic solutions or solid substrates is well documented, considerably little information is available on the effects of Cd in in vitro cells. However, in vitro cultures not only have already shown to be a suitable system to assay toxicity tests (e.g. salt or Hg stress, etc), but also they are potential tools for the selection of Cd tolerant cells. In the present report, the effects of Cd toxicity on some metabolic parameters were compared in sunflower cells growing in vitro and in situ. Proline content is intimately linked with several stress conditions in plant cells and, although its role is not completely clarified yet, it seems to have some protective functions in the cells. Sunflower plants and calli were exposed for three weeks to increasing concentrations of Cd (0.5; 5; 50 e 500 mM). Proline content was determined. This iminoacid increased in both stressed plants and calli cells. In plants, proline increased mostly in roots than in shoots. The higher increase was observed in 5 mM Cd. Higher concentrations although increasing proline Some enzymes involved in proline metabolism (P5-CR, proline oxidase, OAT) were also assayed. The behaviour of proline content is in tune with the behaviour of some the enzymes involved in its metabolism. These results support previous findings (Gomes et al., 1999) that point towers a higher resistance to Cd stress exhibited by in vitro cells respectively to plants and show that prolin metabolism is affected by heavy metals. Key words: sunflower, cadmium toxicity, senescence, proline metabolism |
