Timing of the protein changes during phase transition in cineraria

Shoot apices in vegetative plants of cineraria cv. Cindy Dark Red growing in the juvenile (5 and 6 leaves initiated), transition (7 leaves) and competent (9, 12, 16, 20 and 22 leaves) phases of development were labelled with [S-35]-methionine. Proteins were then extracted from the shoot tips and separated by SDS-PAGE and examined through autoradiography. Clear and consistent quantitative differences in banding intensity between juvenile, transition and competent phases were observed. Four bands appear to change in banding intensity at the time of phase transition. Two proteins (21 and 23 kD) were found to be predominant in the juvenile phase with their intensities degrading during phase transition to almost extinct in competent plants. In contrast, two proteins (40 and 53 kD) were found to increase in intensity from the transition to the competent phase, and then their expression remained almost constant in competent plants as they grew older. No qualitative differences in protein were apparent between plants in different phases.