Genome-Wide Identification and Characterization of SQUAMOSA-Promoter-Binding Protein (SBP) Genes Involved in the Flowering Development of Citrus Clementina

SQUAMOSA-promoter binding protein (SBP)-box genes encode a family of plant-specific transcription factors that play vital roles in plant growth and development. In this study, 15 SBP-box genes were identified and isolated from ( ), where 10 of these genes were predicted to be putative targets of microRNA156 (CclmiR156). The 15 genes could be classified into six groups based on phylogenetic analysis, diverse intron⁻exon structure, and motif prediction, similar to the gene family of and . Furthermore, classified into a group/subgroup have similar gene structures and conserved motifs, implying their functional redundancy. Tissue-specific expression analysis of demonstrated their diversified expression patterns. To further explore the potential role of during floral inductive water deficits, the dynamic changes of the 15 were investigated during floral inductive water deficits, and the results showed that some were associated with floral induction. Among these genes, was not homologous to the SBP-box gene family, and was regulated by being alternatively spliced. Therefore, and were genetically transformed in . Overexpression of the two genes changed the flowering time of .