STUDIES ON BULK PRODUCTION OF CYTOPLASTS FROM HYPOCOTYL OF BRASSICA NAPUS

Bulk cytoplasts were produced from hypocotyl protoplasts of B. napus by means of a discontinuous Percoll density gradient centrifugation or treatment with acridine orange (AO)followed by exposure to light irradiation. More than 80% cytoplastswere obtained in the interphase between WSsolution and 5% Percoll in a discontinuoustwo step gradients after 60 min centrafugation at 12 C30 000 g(18000 r/min). The protoplasts treated with 80 mg/L AO (14～18 h during maceration) plus 3 h irradiation(4000 lx), 100 mg/L AOplus 2 h irradiation or 120 mg/L AO plus 1 h irradiation seldom divided in culture,but could survive for more than 5 days. As light induced fragmentation of AO-DNA complex resulting in degradation of DNA,the nucleus inactivated irreversibly,thus the products may by considered as cytoplasts.