GENOME-WIDE CHARACTERIZATION, EVOLUTIONARY ANALYSIS, AND FUNCTIONAL PREDICTION OF THE BCCP GENE FAMILY IN HELIANTHUS ANNUUS
TL;DR
This study offers the first glimpse of the evolutionary, structural, and functional importance of the BCCP gene family in sunflower, revealing that duplication has led to family expansion while critical metabolic functions in fatty acid synthesis have been preserved.
Abstract
The biotin carboxylase carrier (BCCP) is an essential component of the acetyl-CoA Carboxylase complex (ACCase), responsible for catalyzing the initial reaction of fatty acid synthesis and therefore is crucial for plant growth, development, and production of oil. Sunflower (Helianthus annuus L.) is an economically important oilseed crop; however, a genome-wide analysis of the BCCP gene family in this crop has not been reported. In this study, a genome-wide analysis of the BCCP gene family in H. annus was performed to determine its evolutionary history, duplication events, and genomic structures and predict potential functions. A total of ten HaBCCP genes were identified to be unevenly distributed across the eight sunflower chromosomes, revealing a dispersed genomic distribution largely driven by segmental duplication. Phylogenetic clustering of the BCCP genes into three distinct clades suggested that the diversification of the BCCP gene family occurred before species divergence and that the sunflower BCCP genes are orthologous to members from Arabidopsis thaliana, Brassica juncea, Gossypium hirsutum, Oryza sativa, Glycine max, and Solanum tuberosum. The Domain and Motif analysis identified highly conserved catalytic regions among numerous HaBCCP genes, while structural divergence in some genes revealed lineage-specific functional specialization. Subcellular localization analysis revealed that the majority of the BCCP proteins are targeted to chloroplasts or plastids, in line with their role in fatty acid biosynthesis, while the targeting of the other members to the cytoplasm, mitochondria, endoplasmic reticulum, and nucleus suggested wider functional diversification within the family. The cis-regulatory elements analysis revealed an abundant amount of these elements involved in hormonal signaling, light responsiveness, stress responsiveness, and development, suggesting that the HaBCCP genes are regulating diverse physiological processes. Ka/Ks analysis showed that duplicated HaBCCP gene pairs have been subjected to strong purifying selection, indicating that the function of this gene family has been conserved despite gene duplications. Additionally, intra-genomic synteny analysis confirmed segmental duplication as the primary driver of family evolution, and protein-protein interaction analysis identified a closely coordinated interaction network with HaBCCP3 and HaBCCP10 as the hub proteins. In summary, this study offers the first glimpse of the evolutionary, structural, and functional importance of the BCCP gene family in sunflower, revealing that duplication has led to family expansion while critical metabolic functions in fatty acid synthesis have been preserved. This work provides a solid genomic foundation for future functional studies of the BCCP genes and also provides potential targets for enhancing oil production and metabolic efficiency in sunflower.