Dual regulation of ETT/ARF3 expression by AS2 to determine the adaxial-abaxial polarity of Arabidopsis leaves

Abstract

The ASYMMETRIC LEAVES2 (AS2) and ASYMMETRIC LEAVES1 (AS1) genes of Arabidopsis 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. We previously showed that AS2 regulates leaf polarity by repressing ETT/ARF3, KAN2, YAB5, which are abaxial determinants. To assess whether AS2 acts directly regulates ETT, KAN2, YAB5, we used glucocorticoid receptor (GR)-mediated inducible system. After the treatment 35S:AS2-GR plants with DEX, expression of ETT was decreased rapidly, but those of KAN2 and YAB5 were not changed within 12 hours. ETT is known to be a target of trans-acting siRNA, tasiR-ARF, which in turn regulated by miR390. We report how AS2 regulates the ETT expression in the process of leaf development.