STIMULATION OF GROWTH INDUCED BY BRASSINOSTEROID AND CONDITIONING FACTORS IN PLANT-CELL CULTURES

The multiplication of plant cells in culture is strongly dependent on cell density. To obtain division of single cells in culture conditioning factors (CF) produced by cells themselves must be present in the medium. We have demonstrated that different classes of CF are produced by cells. We have previously isolated and partially characterized, one class of CF that stimulate growth in diluted carrot cell suspensions. The effect of CF on the increase of plating efficiency can be mimicked by 24-epibrassinolide (BR). However BR, unlike CF, induces cell enlargement and its action is synergistic with CF. Experiments on cross-conditioning between different species have demonstrated that interspecific conditioning is more effective than the intraspecific one.