Differential responses persist in shoot explants regenerated from callus of two mature black locust trees.

Callus cultures were established from internodal segments of shoot cultures from two mature black locust Robinia pseudoacacia L. trees. Callus of both trees produced shoots on Murashige and Skoog (MS) medium supplemented with 10 microM 6-benzylaminopurine alone or in combination with 1 microM naphthaleneacetic acid. Regenerated shoots were successfully multiplied on MS medium containing 0.32 microM 6-benzylaminopurine, and produced roots on 0.1 strength MS medium containing 1 microM indole-3-butyric acid. One clone consistently outperformed the other with respect to shoot proliferation and proportion of shoots that produced roots. This distinction had previously been observed in shoots produced from bud explants obtained from the mature trees.