Genome-Wide Identification, Phylogenetic and Expression Pattern Analysis of Fatty Acid Desaturase Genes in Castor ( Ricinus communis L.)

Fatty acid desaturase (FAD) plays a crucial role in plant growth, development, and stress response. The FADs have been identified and reported in diverse plants, but so far, the whole genome exploration and analysis of FADs in castor ( Ricinus communis L.) have not been reported yet. In this study, the identification of the RcFADs was carried out using a sequence alignment method. The physicochemical properties, gene structure, protein motifs, evolution, as well as gene expression under cold stress and different tissues were analyzed. A total of 16 RcFADs in the castor genome were identified, which contained the TMEM189_B_domain (PF10520)/FA_desaturase (PF00487)/FA_desaturase_2 (PF03405) conserved domain. Phylogenetic analysis showed that RcFADs can be categorized into ω-3, ω-6, ADS/SLD/DES, FAD4, and FAB2 groups, indicating that the function of RcFADs may vary. RNA-Sequencing and real-time PCR showed that the expression of RcFAD4 and RcFAD8.1 were increased with the duration of cold treatments, indicating their involvement in cold adaptability of castor. Global expression profiles of the RcFADs in different tissues displayed diverse expression patterns, which suggested that these genes might play important roles in regulating different developmental and physiological processes in castor. This study provides valuable information for understanding the potential function of RcFADs in regulating the growth and development and abiotic stress responses in castor.