Roles of transcription factor SQUAMOSA promoter binding protein-like gene family in papaya (Carica papaya) development and ripening

SQUAMOSA promoter binding protein-like (SPL) family plays vital regulatory roles in plant growth and development. The SPL family in climacteric fruit Carica papaya has not been reported. This study identified 14 papaya SPLs (CpSPL) from papaya genome and analyzed their sequence features, phylogeny, intron/exon structure, conserved motif, miR156-mediated posttranscriptional regulation, and expression patterns. 14 CpSPLs were clustered into 8 groups, and two distinct expression patterns were revealed for miR156-targeted and nontargeted CpSPLs in different tissues and fruit development stages. The expression changes of CpSPLs in ethephon and 1-MCP treated fruit during ripening suggested that the CpSPLs guided by CpmiR156 play crucial roles in ethylene signaling pathway. This study sheds light on the new function of SPL family in fruit development and ripening, providing insights on understanding evolutionary divergence of the members of SPL family among plant species.