Clonal analysis of the late flowering fca mutant of Arabidopsis thaliana: Cell fate and cell autonomy

Plants that are homozygous for the fca mutation bolt and flower later than wild-type (FCA) plants, The mutation has little or no effect on the fate map of the dry seed, except that the central cells give rise to further rosette leaves instead of the bolting stem, cauline leaves and inflorescence, The large and variable sectors affecting the late rosette leaves of fca plants were used to generate an abstract frequency-distance fate map of vegetative growth, The map relates the initiation of leaves in the plant apex to their final arrangements, The map was found to be a shallow dome with phyllotaxy superimposed on its surface. X-irradiation was used to provoke loss of the FCA allele from cells in heterozygous seeds, The resulting fca sectors had no effect on the plant phenotype, Even when L(2) and L(3) cells at the centre of the meristem could not produce the FCA gene product, bolting and flowering was unaffected. The genotypically fca mutant tissue was incorporated into phenotypically normal stems, cauline leaves and flowers, Possible reasons for the non-autonomous behaviour of the trait are discussed.