Abstract
The plant specific transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3) has been considered to function in ABA signaling during seed maturation and germination in angiosperms. ABI3 is evolutionarily conserved among land plants including the moss Physcomitrella patens. ABI3s from seed plants are known to regulate gene expression via ABA responsive element (ABRE) and/or RY sequence in seed plants. To gain insights into how ABI3 regulates ABA-responsive genes in Physcomitrella, we performed a promoter analysis of a Physcomitrella LEA gene (PpLEA1) required for ABI3-mediated activation using Physcomitrella transient assay. We identified a 10-base region is essential for activation by ABA and ABI3. The region contained 5'-CCACTTGTC-3', which is closely related to DistB ABRE of a Brassica napus napA gene promoter or Em1a ABRE of a wheat Em gene promoter. These results suggest that ABI3-mediated regulation of gene expression is evolutionarily conserved between Physcomitrella and seed plants.
