Identification, evolution, and expression analysis of SBP-box gene family in kiwifruit (Actinidia chinensis Planch.)

The Squamosa promoter binding protein (SBP)box genes encode a kind of plant-specific transcription factors, and play important roles in plant growth, development, biotic and abiotic stress. Although the genome-wide analysis of SBP-box gene family has been performed in some species, SBP-box gene family in kiwifruit (Actinidia chinensis Planch.) remains poorly understood. In this study, 25 SBP-box genes of kiwifruit were identified in the kiwifruit genome. Based on phylogenetic and comprehensive bioinformatics analysis, 25 kiwifruit SBP-box genes can be classified into eight groups. Additionally, detailed gene structure, conserved domain, motif compositions, and phylogenetic relationship of the AcSBP genes were systematically characterized. Synteny analysis indicated that segmental duplication has likely contributed to the expansion and evolution of the AcSBP genes. Expression analysis revealed that all the AcSBP genes showed distinct expression levels in five different tissues, and suggested AcSBP genes are significantly involved in response to different plant hormone, drought, salt, and Psa treatments to mimic biotic and abiotic stresses. The genome-wide identification and characterization of SBP-box gene family could facilitate the functional analysis ofAcSBP genes and provide information of the molecular basis of development and stress tolerance in kiwifruit.