XVI International Botanical Congess

AINTEGUMENTA (ANT) has been shown previously to be involved in floral organ initiation and growth in Arabidopsis. ant flowers have fewer and smaller floral organs and possess ovules which lack integuments and a functional embryo sac. Ectopic expression of ANT under the control of the constitutive 35S promoter results in the development of larger floral organs. The number and shape of these organs is not altered and the size of vegetative organs is normal. Microscopic and molecular analyses indicate that the increased size of 35S::ANT sepals is due to increased cell division, while the increased sizes of 35S::ANT petals, stamens, and carpels are primarily due to increased cell expansion. These results suggest that ANT can control organ growth in flowers by regulating not only cell division but also cell expansion.