Genome-Wide Characterization and Anthocyanin-Related Expression Analysis of the B-BOX Gene Family in Capsicum annuum L.

Abstract

The transcription factors, B-box (BBX), belong to a subfamily of the zinc finger family of proteins and exhibit multiple biological functions in plant growth, development, and abiotic stress response pathways. In this study, a total of 23 <i>CaBBX</i> members were identified using the pepper reference genome database. According to the gene structure, conserved domains, and the phylogenetic tree, 23 <i>CaBBX</i> genes were divided into four groups, wherein the analysis of the promoter region indicated the presence of <i>cis</i>-acting elements related to plant development, hormones, and stress response. Interspecies collinearity analysis showed that the <i>CaBBXs</i> had three duplicated gene pairs, and the highest gene density was found on chromosomes 2 and 7. Transcriptome RNA-seq data and quantitative polymerase chain reaction (qRT-PCR) analysis of pepper plants spanning the entire period showed that more than half of the <i>CaBBX</i> genes were widely expressed in diversity tissues of pepper. Co-expression network analysis indicated that the <i>CaBBXs</i> and the anthocyanin structural genes had a close co-expression relationship. Thus, it was reasonably speculated that the <i>CaBBX</i> genes may be involved in the regulation of anthocyanin biosynthesis. Overall, this study involved the genome-wide characterization of the <i>CaBBX</i> family and may serve as a solid foundation for further investigations on <i>CaBBX</i> genes involved in the anthocyanin synthesis mechanisms and development in pepper.