Genome-Wide Identification of Litchi SPL Gene Family and Expression Analysis in Pericarp Anthocyanin Biosynthesis

During the ripening of litchi (Litchi chinensis Sonn.) fruit, anthocyanin biosynthesis is crucial in providing vibrant coloring. Previous studies on anthocyanin-related transcription factors have made significant discoveries relating to plants. However, the role of the SQUAMOSA promoter-binding protein-like (SPL) transcription factors in anthocyanin biosynthesis has rarely been studied in litchi. SPL genes are widely involved in the developmental mechanisms of plants. In this study, a total of 17 SPL genes have been identified from the litchi genome. Phylogenetic analysis revealed that these genes were divided into eight groups (Group I-VIII). Analysis of gene structure conserved domains, conserved motifs, and miR156 target prediction showed that LcSPLs were highly conserved during evolution. RNA-seq analysis of litchi revealed that six LcSPL genes have a role in regulating anthocyanin biosynthesis. Further, weighted correlation network analysis (WGCNA) revealed LcSPL7's role in anthocyanin synthesis and chlorophyll degradation in litchi fruit ripening. These findings collectively suggest that the LcSPL gene family plays an essential role in anthocyanin biosynthesis in litchi pericarp. In summary, comprehensive bioinformatics analysis of the SPL family expands our understanding of anthocyanin synthesis in litchi pericarp.