Cloning And Sequence Analysis Of α-galactosidases Promoter In Cucumber (Cucumis Sativus L.)

α-galactosidases exist widely in higher plants and has important physiological functions. Presently, the research on the plantα-galactosidases is lagging behind when comparing with sucrose-metabolizing enzymes. Cloning promoter sequences of these genes would provide important clues and new tools for further study of their physiological functions.Firstly, partial genomic fragments of 3α-galactosidase genes were obtained according to their cDNA sequences by PCR, and then some target-specific primers were designed based on these genomic sequences for DNA walking. Finally, promoter region sequences of 3 genes were coloned using DNA Walking SpeedUpTM Premix Kit and TaKaRa Genome Walking Kit (1855 bp before transcriptional start site of alkalineα-galactosidaseⅠ, 1902 bp before transcriptional start site of alkalineα-galactosidaseⅡand 1420 bp before transcriptional start site of acidα-galactosidaseⅡ). In addition,there is a 1613 bp intron in alkalineα-galactosidaseⅡ5′untranslated region, which may be with potential promoter regulating function.Sequence analysis with PLACE software showed that besides basic promoter elements such as CAAT-Box, TATA-Box, the promoter region sequences of 3 cucumberα-galactosidase genes contain some important cis-elements which have been reported, such as: endosperm-specific expression regulatory elements (AACACOREOS GLUB1) related to seed maturation and germination; dehydration stress and dark response element (ACGTATERD1) related to leaf senescence; cold induced response element (MYCCONSENSUSAT) related to plant freezing resistance; ethylene-induced response element (ERELEE4) related to fruit ripening, and pathogen-induced response element (OSE2ROOTNODULE) related to plants defense response after infection by the disease. The existence of these elements further indicates thatα-galactosidases may play wide and important roles in cucurbits. In conclusion, the cloning of the promoter region of 3 cucumberα-galactosidase genes will facilitate the functional genomic study of these genes, such as the use of promoter reporter assay.