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The shoot apex development during the life cycle of Crocus sativus L. was characterized by light microscopy and two-dimensional gel electrophoresis. Using silver staining of polyacrylamide gels, numerous quantitative and qualitative changes in the populations of polypeptides were observed during transition from vegetative to prefloral and from prefloral to floral stages. Using 80 μg protein, we were able to detect 352 polypeptidic spots. In comparison with the vegetative apex, 89 new polypeptides were identified in the prefloral meristem and 29 polypeptides were missing. In the reproductive meristem, 94 new spots were identified and 44 spots were missing. Thus, substantial quantitative and qualitative changes in the populations of polypeptides occurred during the prefloral stage, a point of no return in plant development, i.e., and before floral primordia initiation.