Received January 2, 2006
Returned for revision January 30, 2006
Accepted May 12, 2006
AINTEGUMENTA contributes to organ polarity and regulates growth of lateral organs in combination with YABBY genes
Staci Nole-Wilson and Beth A. Krizek *
Department of Biological Sciences, 700 Sumter St., University of South Carolina, Columbia, SC 29208, USA
* Corresponding author; email: krizek{at}sc.edu.
Lateral organs in flowering plants display polarity along their adaxial-abaxial axis with distinct cell types forming at different positions along this axis. Members of three classes of transcription factors in Arabidopsis thaliana (the Class III homeodomain/leucine zipper (HD-ZIP) proteins, KANADI proteins, and YABBY proteins) are expressed in either the adaxial or abaxial domain of organ primordia where they confer these respective identities. Little is known about the factors that act upstream of these polarity-determining genes to regulate their expression. We have investigated the relationship between AINTEGUMENTA (ANT), a gene that promotes initiation and growth of lateral organ primordia, and polarity genes. Although ant single mutants do not display any obvious defects in organ polarity, loss of ANT activity in combination with mutations in one or more YABBY genes results in polarity defects greater than those observed in the yabby mutants alone. Our results suggest that ANT acts in combination with the YABBY gene FILAMENTOUS FLOWER (FIL) to promote organ polarity by upregulating the expression of the adaxial-specifying HD-ZIP gene PHABULOSA (PHB). Furthermore we show that ANT acts with FIL to upregulate expression of the floral homeotic gene, APETALA3 (AP3). Our work defines new roles for ANT in the development of lateral organs.
