Fig. 2

Transient EYFP gene expression as directed by SCBV21 and its deletions in sugarcane. a Schematic map of full-length SCBV21 [1816 base pair (bp)] and its deletions. Nucleotide (nt) 1 is the first nt at the 5′ end of SCBV21. Deletions are indicated by dotted lines and their nt position of each deletion is indicated above the dotted line. The region between SCBV21 and EYFP, marked with an asterisk (*) in deletion A, is derived from the multicloning site of pGEM T-Easy vector and is removed from all deletion fragments. In deletions C and D, the guanine base (G) at nt 1816 was deleted during cloning. Three important restriction enzyme sites, XhoI, StuI, and NcoI used for deletions are marked in deletion A. The two potential promoter regions (PPR1 and PPR2) of SCBV21, which are 632 bp apart from each other, are shown with unfilled square boxes. The approximate position of primers used to generate deletions is indicated with filled arrowheads. b, c Monitoring of transient EYFP expression as directed by SCBV21 and its deletions in sugarcane young leaf segments. Representative images were collected with a stereomicroscope (Olympus SZX7, Olympus) fitted with YFPHQ filters (excitation of 490–500 nm and emission of 515–560 nm) and a DP71 digital camera (Olympus) (×15 magnification) for 48 h post-DNA bombardment (scale bar 2.0 mm). EYFP expression levels were scored as high (+++), medium (++), low (+), and none (−), based on the EYFP focus count and EYFP expression level (mean gray value × pixels)