Abstract
Here we report the isolation and characterization of a novel bZIP-encoding cDNA from rice which belongs to the lip19 subfamily. The cDNA showed highest identity (60.9% and 86% at DNA and amino acid sequence levels, respectively) to OBF1 from maize, thus named OsOBF1 (Oryza sativa OBF1). The gene product, OsOBF1, localizes in nuclei and binds to the hexamer sequence 5'-ACGTCA-3' but is unable to bind the ocs sequence, differing from the DNA binding specificity of maize OBF1. In an in vitro system OsOBF1 not only takes a homodimer form but also a heterodimer form with LIP19. OsOBF1 transcripts were abundantly detected in young mature leaf blades, whereas lip19 ones were more accumulated in senescing leaf blades. Based on those data, we will discuss a function of OsOBF1 and a possible role in transcriptional regulation of a heterodimer of OsOBF1 and LIP19 in growth development and stress response in rice plants.
