SOME FACTORS RELATED TO PROTOPLAST CULTURE AND PLANT-REGENERATION FROM LEAF MESOPHYLL PROTOPLASTS OF MAGDEBURG CHICORY (CICHORIUM-INTYBUS L VAR MAGDEBURG)

Conditions have been established for efficient plant regeneration from protoplasts of the cultivar Pevele of Cichorium intybus L var Magdeburg. In order to increase the yield of protoplasts which are able to undergo cell divisions during the first week of culture, protoplasts of Magdeburg chicory were cultured in a Murashige and Skoog (1962) modified medium containing 2 mg/l ANA, 1 mg/l BA, 10 g/l sucrose, a mixture of glutamine-KNO3 as nitrogen source and were placed at a temperature of 30-degrees-C. With this method, cell walls can be regenerated within 24 h and after a lapse of 1-2 d, cell division became apparent and continuous divisions led to callus formation and then to plantlet regeneration. Special emphasis has been paid to leaf material for protoplast culture. Donor plantlets, aged 14 d and cultivated in a photoperiod of 16:8 h under a light intensity of 15 W.m-2 (fluorescent light tubes "Deluxe Cool White") gave a better yield of microcalli. These were then incorporated in a proliferation medium containing agarose at low gel temperature. During this phase it is better to use Petri dishes of large diameter regardless of the amount of microcalli transferred.