Molecular Evolution, Genome-Wide Characterization and Codon Bias Analysis of the SBP-Box Family in Cucumis sativus

Abstract Background: SQUAMOSA promoter binding protein (SBP)-box genes encode a group of transcription factors which extensively play essential roles in plant development and stress responses. However, the SBP-box gene family has not been well characterized in cucumber (Cucumis sativas). Results: In present study, 15 putative SBP-box genes were identified distributing on 4 chromosomes of cucumber. Evolutionary analysis showed that the green plant SBP family originated from a common ancestor. Phylogenic analysis divided CuSBPs into 6 groups similar to those of Arabidopsis and rice. Intron-exon and motif structure within each group shared common features according to evolutionary study. Expression pattern analysis of transcriptional data about flowering and resistance to powdery mildew demonstrated conserved SBP-box genes function in vegetative-to-reproductive transition and potential roles in other regulatory pathways. Moreover, codon bias analysis explained the mutation and selection pressure exerted on genes. Conclusions: This study comprehensively characterized cucumber CuSBP gene families, which would provide a foundation to explore the functions of CuSBPs for improving yield, quality and stress tolerance of cucumber in the future.