EFFECT OF WATER-STRESS ON GROWTH, OSMOTIC POTENTIAL AND SOLUTE ACCUMULATION IN CELL-CULTURES FROM CHILI-PEPPER (A MESOPHYTE) AND CREOSOTE BUSH (A XEROPHYTE)

Cell cultures were established from the drought sensitive chili pepper (Capsicum annuum L.) and from Larrea tridentata, a plant species highly tolerant to drought. The cell cultures were exposed to water stress imposed by the presence of polyethylene glycol (PEG) in the culture medium. Cell cultures of L. tridentata showed higher resistance to PEG (6.6 times higher) than those of C. annuum. More negative psi(s) values were found to occur in cell cultures of L. tridentata in response to PEG as compared to cell suspensions from chili pepper. Analysis of solutes revealed an important contribution of K+ to psi(s), K+ levels were higher in chili pepper cells than in L. tridentata cultures. The Na+ and Ca2+ contents in the cell suspensions of the two species did not contribute significantly to psi(s). A positive correlation was observed between proline accumulation and the capacity of cell cultures to grow in conditions of water stress. Glycine betaine levels did not show a positive correlation with drought resistance.