Analysis of downstream target of ASYMMETRIC LEAVES2 in the leaf development

Abstract

The ASYMMETRIC LEAVES2 (AS2) and ASYMMETRIC LEAVES1 (AS1) genes of Arabidopsis thaliana are required for symmetrical and flat lamina expansion. AS2 encodes a plant specific protein that contains AS2/LOB domain, and AS1 encodes a myb (SANT) domain protein. AS2 and AS1 are thought to act as a transcriptional regulator of certain genes including class 1 KNOX genes. To identify the downstream target of AS2, microarray analysis of mRNA from shoot apices was performed. Several candidate genes to be downstream target were identified, and ETTIN(ETT)/ARF3 was selected for the genes whose expression levels were increased in as1 and as2 but decreased in pAS1::AS2 plants. ETT specifies abaxal organ polarity, and known to be a target of TAS3 ta-siRNA. The altered expression levels of ETT were confirmed with real-time PCR. We report how AS2 regulates the ETT expression in the process of leaf development.