Transcriptional repressor that regulates multiple aspects of plant growth and development through the regulation of BEL1-LIKE (BLH) and KNOX TALE (KNAT) homeodomain transcription factors. Forms a transcription repression complex with KNAT7 which regulates secondary cell wall formation. Interacts with BLH1, BLH2, BLH3, BLH6, BLH10, KNAT1, KNAT3, KNAT4, KNAT5, KNAT6 and KNAT7. Expressed in root vascular cylinder, root tips, xylem of stems, flower buds and siliques. Moderate irregular xylem, but normal plant morphology. Plants over-expressing OFP4 show kidney-shaped cotyledons, round and curled leaves, small rosette size, late flowering, reduced fertilization and round seeds.