Specification of chimeric flowering shoots in wild-type Arabidopsis.

Within wild-type Arabidopsis populations, a subset of the plants were found to have a single chimeric shoot on their primary shoot axes. The chimeric shoots were located below the lowest primary-axis flower; and they exhibited features of both flowers and paraclades (lateral flowering shoots). Morphological analyses of chimeric shoots indicated that they developed from single primordia. In each chimeric shoot, the side furthest from the apical meristem was specified as 'flower'--while the side closest to the meristem was specified as 'paraclade'--suggesting that a stimulus from outside the apical meristem can directly induce primordia to develop as flowers. It is concluded that the development of the teratological chimeric shoots resulted from the overlap of the vegetative and floral specification processes within single primordia.