Improvement of Cell Culture Conditions for Rice
Cell culture techniques are necessary for the use of biotechnology including the production of transgenic rice plants. However, there are significant differences in vitro culture responses among rice varieties. These differences limit the application of biotechnology to genetic improvement of rice. In this study, it was demonstrated that nitrite reductase activity is one of the physiological factors correlated with the differences among rice varieties in cell culture. It was indicated that the modification of the culture medium was effective in overcoming the differences in cell culture: the calluses of some Indica and Japonica type varieties showed a poor growth or did not grow under the initial conditions, whereas the calluses of all the varieties tested showed good growth when the nitrogen source, carbon source and medium pH were modified. As a result, in this stud, the culture conditions applicable to a wider range of varieties, including Indica type, Javanica type and Indica-Japonica crossed varieties as well as Japonica type were identified.