AN IMPROVED PROTOCOL FOR THE CULTURE OF CASSAVA LEAF PROTOPLASTS

Viable protoplasts (yield > 1.9 x 10(7) g(-1) fresh weight; mean viability 85 +/- 2%, n = 5) were isolated from leaves of axenic shoot cultures of Manihot esculenta Crantz. cv. M. Thai 8. Protoplasts were cultured for up to 50 days in liquid, ammonium-free MS medium, overlaying agarose-solidified B5 medium with short glass rods embedded perpendicularly within, and protruding from, the agarose layer. Control protoplasts were cultured identically, but without glass rods. Sustained protoplast division was observed only in the presence of glass rods, where the initial plating efficiency was almost 6-fold greater than control (p < 0.05). The mean final plating efficiency of treated cultures was 1.0 +/- 0.2% while, in contrast, significant colony formation was not observed in controls.