Genetic Transformation

Abstract

The workshop was opened on a critical note by H. H. Steinbiss with a brief demonstration of the flexibility of calculations of transformation frequency. Frequencies between 10^-6 and 1 were derived from the same set of data from poster PF 4, depending on the criterion used for calculation. The ways in which such frequencies are determined by different workers makes comparison of published protocols difficult, especially when covert selection steps are involved as in some coculture experiments with Mitchell petunia, where transformed cells survive better than normal ones even without selection for hormone autotrophy. Two main methods were suggested: Either parallel non-treated and unselected duplicates should be carried through for counting of the plating efficiency, or the plated microcalli at the beginning of the selection step should be used as a basis. The latter was criticised as not accounting for clumping and L. Marton (Hungary) suggested that a short term cellulase treatment should be applied immediately after the coculture step to disperse the clumps.