Genome-Wide Identification of the BTB Domain-Containing Protein Gene Family in Pepper (Capsicum annuum L.)

Pepper (<i>Capsicum annuum</i> L.), recognized as a globally preeminent vegetable, holds substantial economic and nutritional value. The BTB (broad-complex, tramtrack, and bric-a-brac) family of proteins, characterized by a highly conserved BTB domain, also denoted as the POZ domain, are intricately involved in a diverse array of biological processes. However, the existing corpus of research regarding pepper <i>BTB</i> genes remains relatively meager. In this study, a total of 72 <i>CaBTB</i> gene members were meticulously identified from the entire genome of pepper. Phylogenetic analysis illuminated the presence of conspicuous collinear relationships between the <i>CaBTB</i> genes and those of its closely affiliated species. Gene expression profiling and RT-qPCR analysis revealed that multiple <i>CaBTB</i> genes exhibited pronounced differential expression under diverse treatment regimens. Expression pattern analysis unveiled that <i>CaBTB25</i> manifested a remarkably elevated abundance in leaves. Moreover, its promoters were replete with an abundance of light-responsive <i>cis</i>-elements. Our comprehensive and in-depth explorations into subcellular localization revealed that CaBTB25 was predominantly detected to localize within the nucleus and lacked transcriptional activation. This research provides a crucial theoretical edifice, enabling a more profound understanding of the biological functions of the <i>BTB</i> gene family in pepper, thereby underscoring its potential significance within the intricate network of gene-environment interactions.