Induction of Cell Division of Isolated Pollen Grains by Sugar Starvation in Rice.

Cell division of isolated immature pollen grains was induced by sugar starvation in rice cv. Nipponbare. Irmuature pollen grains were isolated from a freshly harvested panicle without any pretreatuent. The pollen suspension was fractionated based on the size (37-50μm in diameter) and density (lighter than 35 % Percoll solution) of the grains. The fraction was incubated in a sugar-free medium consisting of R2 salts with various concentrations of KH2PO4 instead of NaH2PO4, B5 vitamins and 0.5 mg/l 2, 4-D (pH 5.8). After sugar starvation, a sucrose solution was added to a final concentration of 5 InM. Sugar starvation was essential to induce cell division of the pollen grains and the optimum period of sugar starvation was three days. The optimum concentration of KH2PO4 in the medium was 1 mM for induction of cell division. It was shown that sugar starvation for three days in the medium containing I mM KH2PO4 resulted in the highest frequency of colony fornration at 0.04%. Out of 200 calli, three produced green plants while 15 produced albino plants.