Abstract
FUS3, a key transcription factor controlling seed maturation, regulates the expression of seed specific genes including the SSP genes. Microarray analysis using transgenic plants carrying an inducible FUS3 transgene revealed that FUS3 regulated genes are categorized into several groups with respect to induction kinetics and ABA-dependencies, suggesting distinct mechanisms of FUS3 action. Members of the SSP gene families (the Napin and Cruciferin families) belonged to different groups. The FUS3 induction of CRC (a Cruciferin member) took much longer periods than that of At2S3 (a Napin member), indicating that the FUS3 regulation of CRC required intermediate regulatory factors whose synthesis was regulated by FUS3 and ABA. The microarray analysis identified eighteen FUS3-induced transcription factors. Cotransfection experiments revealed that the bZIP67 and bZIP12 among them were able to activate the CRC promoter. Thus, these bZIP factors are the strong candidates for the intermediate factors that function in the FUS3 regulation of CRC.
