AN IMPROVED PROTOCOL FOR THE CULTURE OF CASSAVA LEAF PROTOPLASTS

Viable protoplasts (yield > 1.9 x 10(7) g(-1) fresh weight; mean viabi lity 85 +/- 2%, n = 5) were isolated from leaves of axenic shoot cultu res of Manihot esculenta Crantz. cv. M. Thai 8. Protoplasts were cultu red for up to 50 days in liquid, ammonium-free MS medium, overlaying a garose-solidified B5 medium with short glass rods embedded perpendicul arly within, and protruding from, the agarose layer. Control protoplas ts were cultured identically, but without glass rods. Sustained protop last division was observed only in the presence of glass rods, where t he 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 o bserved in controls.