Identification and Characterization of a SEPALLATA-like MADS-box Gene from Cucumber (Cucumis sativus L)

SEPALLATA (SEP) genes encode the E class MADS-box transcription factors that play vital roles in various aspects of plant growth and development. In this study, we isolated a SEP-like gene from cucumber (Cucumis sativus L.), which was previously named as CsMADS01. CsMADS01 had a coding sequence (CDS) of 741 bp, and coded a deduced protein of 246 amino acid residues that was predicted to be located in the nucleus. The putative CsMADS01 protein was typically characterized by the MIKC-type MADS (including MADS, I, K, and C domains) and shared high homology with other SEP-like proteins. Phylogenetic analysis of CsMADS01 and SEP proteins from other plants revealed that CsMADS01 was a member of the SEP1/2 clade of SEP proteins and was the most closely related to ZjMADS48 from Chinese jujube. Promoter analysis showed that several cis-elements related to stress response and hormones were present in the promoter region of CsMADS01. Expression analysis indicated that CsMADS01 was highly expressed during the development of male and female flowers, and the expression increased gradually along with fruit development. Ectopic expression of CsMADS01 in Arabidopsis resulted in a phyllody-like phenotype and the transgenic plants never flowered. These results suggest that CsMADS01 plays an important role in the growth and development of cucumber