RESPONSE TO CADMIUM IN CARROT IN-VITRO PLANTS AND CELL-SUSPENSION CULTURES

In vitro grown plants and cell suspension cultures of carrot (Daucus c arota L.) were treated with various Cd concentrations. Stress ethylene production in carrot plants was highly stimulated by 1 mM Cd. A pre-t reatment with buthionine sulfoximine (BSO) did not further increase et hylene production. After being treated with Cd, both plants and cell s uspensions produced phytochelatins, and no lipid peroxidation was dete cted. In cell cultures, the in vitro activity of phytochelatin synthas e was assayed in the presence of Cd and glutathione: the first product (PC2) was detected in less than 30 min. Absence of ethylene (after tr eatment with aminoethoxyvinylglycine (AVG), an inhibitor of ethylene-b iosynthesis, or use of ethylene traps) caused both a decrease in the p hytochelatin synthase activity of cell suspensions and a strong loweri ng in the Cd-induced SH groups in plants. However 1-aminocyclopropane- 1-carboxylic acid (ACC) supply did not increase either phytochelatin s ynthase activity or total SH level. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.