In-depth analysis of potential CaAP2/ERF transcription factor related to fatty acid accumulation in Allotetraploid Coffea arabica and functional characterization of CaAP2.7 in transgenic tomato

Coffee seed oil critically determines beverage mouthfeel, aroma retention, and oxidative stability, yet the transcriptional regulation of fatty acid accumulation in Coffea arabica remains largely unknown. A genome-wide identification analysis of the AP2/ERF superfamily in the allotetraploid C. arabica (cv. Caturra genome) was performed, followed by phylogenetic, motif, promoter, and expression analyses across four seed developmental stages. Fatty acid content and oil body dynamics were quantified concurrently. A total of 214 CaAP2/ERF genes were identified. Five genes, including the WRINKLED1 ortholog CaAP2.7, showed strong positive correlation with lipid accumulation. Constitutive overexpression of CaAP2.7 in tomato fruits increased total fatty acid content by 42-68 %, with palmitic, oleic, and linoleic acids rising to 2.6-fold. Transcriptome profiling confirmed that CaAP2.7 activates the canonical WRINKLED1-regulated network, up-regulating key enzymes of de novo fatty acid synthesis and triacylglycerol assembly. CaAP2.7 is a functional ortholog of WRINKLED1 and a potent positive regulator of seed oil biosynthesis in coffee. These findings provide the first comprehensive CaAP2/ERF genomic resource and a validated high-priority target for the molecular target of breeding C. arabica cultivars with enhanced seed oil content, superior cup quality, and improved nutritional value.