Abstract
Arabidopsis FUS3 is one of the key transcription factors that regulate seed storage protein (SSP) genes expression. Previously, we proposed that the regulation of FUS3-dependent SSP expression involves an indirect mechanism requiring the ABA- and FUS3-dependent synthesis of intermediate regulatory factor(s). Here, we further conducted molecular analysis of FUS3-dependent SSP expression. By in vivo footprinting analysis of the CRC SSP promoter, we identified two ABREs and one ABRE-like element as potential cis elements for the proposed intermediate regulatory factor(s). Northern analysis revealed that the expression of bZIP67, one of the ABRE-binding factors, is regulated in an ABA- and FUS3-dependent manner. Over expression of bZIP67 was found to enhance FUS3-dependent CRC expression. Furthermore, specific in vitro interactions between bZIP67 and the two ABREs in the CRC promoter was confirmed. These results suggested that bZIP67 is one of the intermediate regulatory factors for FUS3-dependent SSP expression.
