AINTEGUMENTA promotes petal identity and acts as a negative regulator of AGAMOUS

The Arabidopsis AINTEGUMENTA (ANT) gene has been shown previously to be inv olved in ovule development and in the initiation and growth of floral organ s. Here, we show that ANT acts in additional processes during flower develo pment, including repression of AGAMOUS (AG) in second whorl cells, promotio n of petal epidermal cell identity, and gynoecium development. Analyses of ap2-1 ant-6 double mutants reveal that ANT acts redundantly with AP2 to rep ress AG in second whorl cells. The abaxial surface of ant petals contains f eatures such as stomata and elongated, interdigitated cells that are not pr esent on wild-type petals. The loss of petal identity in these second whorl cells does not result from ectopic AG expression, suggesting that ANT acts in a pathway promoting petal cell identity that is independent of its role in repression of AG. These data suggest that ANT may function as a class A gene.