Expressing activity of promoter elements of large intergenic region from cotton leaf curl virus in host plant

Cotton leaf curl virus (CLCuV) is a type of single-stranded DNA virus, belonging to geminivirus of subgroup III. In order to determine the function of CLCuV large intergenic region (LIR), total DNA of CLCuV-infected cotton leaves was used as template, and fragment of LIR was obtained by PCR and inserted into clone vector. The fragment of LIR was fused withgus reporter gene andnos terminator in the orientation of transcription of virion sense and complementary sense respectively, and the plant expression vectors were constructed. GUS activity ofAgrobacterium-mediated transgenic tobacco was measured. The result indicated that LIR showed strong promoter activity in complementary sense gene orientation. Average GUS activity of the complementary sense promoter was 5-6 times that of CaMV 35S promoter, and the highest GUS activity of individual plant was ten times of that of CaMV 35S promoter. Histochemical localization confirmed its activity in both mesophyll and vascular tissues. Activity of virion sense of LIR was rather low. Thus LIR isolated from CLCuV could be used as a novel strong promoter in plant genetic manipulation.