ABSTRACT
Mesophyll cell protoplasts were isolated from potato (Solanum tuberosum L. cv. Russet Burbank) leaves and induced to proliferate in culture. Protoplast division was observed only among preparations isolated from plants previously conditioned under short periods of low intensity illumination. Sustained growth and development of protoplast-derived calli (p-calli) occurred when they were maintained on defined media at 24 C under 500 lux lighting. Shoot bud development within p-calli was controlled by a number of factors including light, temperature, basic medium composition, nature and source of phytohormones, the continued presence of an osmoticum, low concentrations of a utilizable carbohydrate, and the developmental stage of the p-callus.
ABSTRACT
A method is described for the isolation of large numbers of tobacco (Nicotiana tabacum L. cv. Xanthi-nc) mesophyll cell protoplasts under relatively low external osmotic conditions. The procedure utilized 0.2 m sucrose as the primary osmoticum and a mixture of 0.5% macerozyme, 4% cellulase, and 2% polyvinylpyrrolidone, pH 5.4. The viability of resultant protoplasts was confirmed through regeneration of fertile plants. Plating and regeneration studies revealed, however, that qualitative and quantitative modifications in plating and differentiation media were necessary for protoplasts prepared in this manner. Over-all, the procedure was found to be a simplified alternative to those previously described for tobacco protoplast regeneration. In addition, the system should permit studies related to the influence of differing osmoticum levels on a variety of cell functions.
