Genome-Wide Characterization of the F-Box Gene Family in Cardamine hupingshanensis and Functional Analysis of ChFBX171

Cardamine hupingshanensis (C. hupingshanensis) is an important dietary source of selenium for humans due to its remarkable capacity for selenium hyperaccumulation. As core components of the SCF (SKP1–Cullin–F-box) ubiquitin ligase complex, F-box proteins play vital roles in plant responses to environmental stress, such as salt and drought. However, information regarding the F-box gene family in C. hupingshanensis and its potential functions in regulating responses to abiotic stress remains limited. In this study, members of the F-box gene family in C. hupingshanensis were identified through sequence alignment. Comprehensive bioinformatic analyses, including analyses of physicochemical properties, phylogenetic relationships, subcellular localization, conserved motifs and domains, gene structure, chromosomal distribution, promoter cis-elements, and gene duplication events, were performed using TBtools and associated online resources. In particular, a total of 548 F-box genes were identified and classified into nine distinct groups based on phylogenetic analysis. Protein sequence analysis predicted 15 conserved motifs and 18 distinct domains across the identified F-box proteins. Promoter analysis suggested the presence of 32 different cis-elements that may be potentially associated with growth, development, hormone signaling, and abiotic stress responses. Furthermore, 283 collinear gene pairs were detected within the C. hupingshanensis genome, providing insights into the possible expansion of this gene family. Quantitative real-time PCR was employed to examine the tissue-specific expression levels of F-box genes in various organs, as well as their expression profiles in response to exogenous selenium, salt, osmotic stress, and abscisic acid treatment. The results indicated that 11 ChFBX genes responded to exogenous selenium, salt, osmotic stress, or abscisic acid. Notably, transgenic plants overexpressing ChFBX171 displayed heightened sensitivity to salt stress during seed germination. In conclusion, this study provides a comprehensive identification and characterization of 548 F-box genes in C. hupingshanensis and offers valuable insights into the potential role of ChFBX genes, particularly ChFBX171, in mediating responses to abiotic stress.