Abstract
The quality of Coffee arabica L. beans, particularly the aroma, is a key determinant of commercial value. Fatty acids, as precursors of volatile aroma compounds, play a crucial role in this quality. Screening and identification of their related genes are of particular significance. This study identified 21 members of the CaFAD gene family in the C. arabica genome using bioinformatics tools. Gene duplication events observed in the CaFAD gene family were likely driven by natural selection and mutation pressure, with natural selection being more prominent. Transcriptome sequencing, qRT-PCR, and fatty acid profiling across four fruit developmental stages revealed that CaFAD8 was closely associated with fatty acid synthesis regulation. Fatty acid content was initially high but decreased during the later stages, while CaFAD8 expression showed an inverse pattern. Subcellular localization indicated that CaFAD8 functions primarily on the inner membrane. CaFAD8-OE heterologous expression experiment in Arabidopsis thaliana reduced the total fatty acid content in seeds but increased unsaturated fatty acids, including oleic, linoleic, and linolenic acids. These findings suggest that CaFAD8 promotes fatty acid unsaturation and provides insights into fatty acid metabolism in C. arabica. This study offers a foundation for understanding CaFAD gene regulation and supports breeding strategies for high-oil C. arabica varieties.