Effect of benzyl adenine on the DNA synthesis during early germination of maize embryo axes

The nature of the DNA synthesized during maize germination has been investigated making use of BND-cellulose chromatography, defining early germination as the first 3 h of imbibition; axes have been pulse-labelled for the last 30 min of the incubation period. The pattern of labelled DNA obtained for γ-irradiated axes is typical of a repair-type synthesis whereas that of non-irradiated axes would be defined as a replicative-type synthesis except that it is insensitive to abscisic acid. However, when benzyl adenine is added to these two types of tissues (irradiated and non-irradiated axes) from the beginning of the incubation period, the result is an increase in the label incorporated, enhancing the repair-type pattern in irradiated axes but most important, switching the “replicative patter” of non-irradiated axes to an unambiguous repair-type pattern. This occurs irrespective of whether the pulse-label is given 10, 20 or 30 min bofore the ent of the incubation period. The role of benzyl adenine on early germination and repair synthesis is discussed.