Genome-Wide Identification of the WD40 Gene Family and Functional Analysis of a Candidate Gene Regulating Seed Quality in Soybean.

Background: Soybean is an important crop with multiple uses for oil, food, and feed, providing 50% of the vegetable protein and 20% of the edible oil in the world. The WD40 family genes play crucial regulatory roles in growth, development, secondary metabolism, and stress responses. However, the definition of WD40 family genes in soybean remained unclear, which limited their application potential in genetic improvement. Methods: To identify soybean WD40 family members and screen candidate genes for breeding improvement, this study performed genome-wide identification of the soybean WD40 gene family via bioinformatic approaches based on the latest Williams 82 reference genome (Wm82.a6.v1). Meanwhile, the function of the family gene GmWD40-257 regulating seed quality was analyzed. Results: The results showed that a total of 458 GmWD40 genes were identified, which were distributed on the 20 chromosomes. Subcellular localization showed that most members were mainly concentrated in the nucleus, chloroplast, and cytoplasm. Phylogenetic tree analysis divided the 458 GmWD40 genes into eight groups. Synteny analysis identified 160 syntenic genes between soybean and Arabidopsis thaliana. Conserved motif analysis identified ten core motifs. The promoter regions of GmWD40 contained 19 types of cis-acting elements. Functional analysis revealed that the nonsense mutation of GmWD40-257 significantly reduced the content of oil, palmitic acid, oleic acid, linoleic acid, α-linolenic acid and soluble sugar, while significantly increasing the contents of protein, γ-tocopherol and δ-tocopherol. Conclusions: A total of 458 members of the WD40 gene family were identified in soybean. Among these, GmWD40-257 was found to positively regulate the contents of soybean oil, palmitic acid, oleic acid, linoleic acid, α-linolenic acid and soluble sugar, while negatively regulating the contents of soybean protein, γ-tocopherol and δ-tocopherol.