Background: Dihydroflavonol 4-reductase (DFR) is a key enzyme in the flavonoid biosynthetic pathway that regulates anthocyanin and proanthocyanidin accumulation in plants. Although DFR genes have been studied in various species, their origin of the DFR gene family, its distribution across the plant kingdom, and the reasons behind the emergence of different DFR subtypes Methods: This study performed a whole-genome analysis of DFR genes in 237 plant species, including algae, mosses, ferns, gymnosperms, and angiosperms, integrating phylogeny, conserved motifs, duplication mechanisms, positive selection, and expression pattern analyses. Results: These results indicate that the DFR gene family originated from the common ancestor of extant ferns and seed plants, and the emergence of asparagine (Asn)-type and aspartic (Asp)-type DFRs is associated with gymnosperms. Notably, we report for the first time the presence of Asn-type, Asp-type, and arginine (Arg)-type DFRs in some species, which breaks the previous notion that Arg-type DFRs are exclusive to ferns. Tandem duplication is considered the primary driving force behind the expansion of the DFR family and is associated with the formation of different DFR subtypes. Furthermore, Asn-type DFRs were highly expressed during the early stages of seed development, suggesting their important role in seed development. Conclusions: Overall, this study revealed the dynamic evolutionary trajectory of the DFR gene family in plants, providing a theoretical foundation for future research on DFR genes.

Background: The RSPO gene family encodes secreted glycoproteins that are rich in cysteine, which generally serve as activators of the Wnt signaling pathway in animals. Four types of this family have been identified in a few model species. However, the evolution of the family remains unclear. Methods: In this study, we identified a total of 1496 RSPO homologs through an extensive survey of the RSPO genes in 430 animals. Gene family clustering and phylogenetic analysis identified four major subtypes of the family (RSPO1–RSPO4) and clarified their distribution of copy number in different species. Results and Conclusions: Members of the RSPO4 subfamily that were closest to ancestral forms existed in both Deuterostomes and Protostomates, and we speculate that representatives of this subfamily already existed in Urbilatera, the last common ancestor of Deuterostomes. Particularly, in some RSPO3 subtypes of Actinopterygii (ray-finned fishes), an FU repeated motif with three conserved cysteines was identified. Further conservative analysis of amino acids and alignment of tertiary protein structure revealed the potential functional sites for each subgroup. The results provide insight into the phylogenetic relationships and evolutionary patterns of conserved motifs of RSPO family genes in animal kingdoms, which will guide further studies on the biological functions of RSPO in other non-model species.