GENOME-WIDE CHARACTERIZATION AND EXPRESSION ANALYSIS OF THE BCCP GENE FAMILY IN SOYBEAN: IMPLICATIONS FOR FATTY ACID BIOSYNTHESIS UNDER SALT STRESS AND MELATONIN TREATMENT

Soybean oil is a complex mixture of triacylglycerols rich in unsaturated fatty acids which are major sources of lipids for human and animal consumption. The biosynthesis of soybean oil, an important agricultural commodity, involves a complex network of enzymes and regulatory pathways. One of the major pathways, BCCP domain of Acetyl-CoA Carboxylase (ACC) is considered as a vital key role player for this process but its role in soybeans remained poorly understood. In this study, the identified and characterized 11 BCCP genes in the soybean genome (GmBCCP) revealed their diverse roles in fatty acid biosynthesis and stress response. One of the 4 subunits of Acetyl-CoA Carboxyl (ACC), BCCP (Biotin Carboxyl Carrier Protein) domain have great importance for fatty acid biosynthesis in plants, impacting the oil content and its composition. To evaluate the composition, function, and structure of this domain in soybean, this study was conducted to explore their gene structures, conserved motifs, chromosomal distribution, physiochemical properties, evolutionary relationships, and expression patterns under melatonin and salt stress. Phylogenetic analysis revealed the evolutionary conservation of GmBCCP genes across diverse oilseed crops, particularly with Arabidopsis. Subcellular localization highlighted their diverse roles in key metabolic compartments of cells. Cis-regulatory element analysis showed the potential functions in stress responses, growth, development, and hormone signaling. The distinction in intron-exon structures indicates potential regulatory complexity through alternative splicing. Gene duplication analysis identified segmental and tandem duplications contributing to the expansion and functional diversification of the GmBCCP gene family. RNA-seq data demonstrated that melatonin treatment upregulated GmBCCP1 and GmBCCP10 expression, potentially stimulating fatty acid biosynthesis. Additionally, melatonin lessened the salt-induced downregulation of GmBCCP2, suggesting its role in stress tolerance. These findings provide a comprehensive groundwork for understanding the functional roles of GmBCCP genes in soybean, with implications for crop improvement strategies for enhancing oil production and stress resilient soybean cultivars. These insights provide a foundation for targeted breeding strategies aimed at enhancing oil yield and developing stress-tolerant soybean cultivars.