Independent callus culture lines were generated from over 5000 immature embryos, ranging from 0.8mm to 6.0mm in length. Callus cultures of the following genotypes were established on both MS (Murashige and Skoog) and N6 callus induction media: inbreds A188, A632, B37, B73, CO159, F2, K55, M14, Mo17, N28, Oh43, TANA, Va26, W23, W64a; an Ontario flint; and the hybrid Seneca 60. Embryo age ranged from 9-18 days post pollination; the cultures were maintained at 26 C with a 18h light/6h dark cycle. Callus was characterized according to established (Type I and Type II) criteria (Torné, 1984), or a third class, Type III. Type III consisted of a very distinct sponge-like texture, with an amber to brown appearance.
Table 1. Types of callus observed for the genotypes over a 5 month period
of culture.
|
|
II | III | I & II | II&III | I&II&III |
| B37 | TANA | A632 | A188 | N28 | M14 |
| CO159 | Va26 | F2 | Seneca 60 | Mo17 | |
| K55 | W64A | ||||
| Oh43 | Ontario Flint | ||||
| W23 |
Table 2. Preferable media for inducing callus based on responses over
a 5 month period of culture.
| MS | N6 | BOTH |
| B73 | B37 | A188 |
| Mo17 | M14 | CO159 |
| N28 | SENECA 60 | |
| W64A | TANA | |
| A632 | VA26 | |
| Ontario Flint | F2 | |
| K55 | ||
| Oh43 | ||
| W23 |
Regenerated plants from callus over a 5 month period were obtained from: A188, A632, B73, CO159, K55, M14, N28, Oh43, Seneca 60, TANA, W23, W64a; and an Ontario flint. Observations on callus growth are summarized in Tables 1 and 2.
An extensive RFLP analysis is underway on samples of callus and regenerated plants.
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