University of Paris
In order to enhance type II callus initiation, more favourable culture conditions have been researched. We have already shown that AgNO3, when added to a modified Murashige and Skoog's medium, increases 4 to 6 fold the rate of type II callus initiation from inbred A188 (Vain et al., Plant Cell Tissue Organ Cult., in press). Here, the effect of three classical gelling agents on maize callus initiation rate is reported.
Fourteen-day-old embryos (1-2 mm long) were aseptically removed from self-pollinated kernels of inbred A188 and plated on Murashige and Skoog's modified medium complemented with 10 mg/l AgNO3, with the embryo axis facing the medium. Cultivated embryos and/or calluses were subcultured every two weeks and callus production was scored at the fifth subculture. Results are given in the following table.
Gelrite is from Siccap-Emmop (France), agar from Difco and agarose from Sigma (Type 1:low EEO); given concentrations are the most commonly used and give roughly the same compactness to the medium.
Both agarose and gelrite proved to be
very well-suited for type I callus initiation (non-friable callus). For
type II callus production, agarose gave the best results, showing a higher
sensitivity of this type of callus to the impurities present in gelling
agents. These results suggest that according to what is wanted and to the
price of those components, using gelrite or agarose rather than agar may
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