FLORAL DEVELOPMENT AND EXPRESSION OF FLORAL HOMEOTIC GENES ARE INFLUENCED BY CYTOKININS

Tobacco plants that are somatic mosaics for the expression of a cytoki nin-synthesizing gene have viviparous leaves. Epiphyllous buds can be either vegetative or floral. Floral adventitious buds can be either no rmal or abnormal. Abnormalities of floral development correlate with: (i) a local activation of the cytokinin-synthesizing gene, (ii) a dras tic increase in floral cytokinin content, and (iii) a decrease in the steady-state levels of mRNA homologues of the homeotic genes DEFA, GLO and PLENA of Antirrhinum majus. Thus, these data show in planta that cytokinins, a class of phytohormones, are able to alter the developmen t of floral organs and to decrease the expression of three homeotic fl oral genes.