FUNCTIONAL-STUDIES OF COMPLEMENTARY SENSE PROMOTER (REPLICASE PROMOTER) FROM TOMATO YELLOW LEAF CURL VIRUS - EVIDENCE FOR TRANSCRIPTION CAPABILITY IN NONHOST PLANTS

The complementary sense promoter C-1 that regulates the transcription of replicase gene in geminiviruses was cloned from tomato yellow leaf curl virus. A transcription fusion of beta-glucuronidase gene (GUS) co ding sequence to complementary sense promoter, that replaced the viral replicase coding sequence, was constructed. Protoplasts of Nicotiana tabacum were electroporated to introduce the GUS gene controlled by th e C-1 promoter. The level of GUS transient gene expression was enhance d by the increase of the plasmid DNA concentration. Fluorometric GUS a ssays showed that the C-1 promoter has a lower expression compared to the e35S promoter. Bombardment of the constructed plasmid, containing C-1 promoter-GUS ORF-NOS terminator (pKSIR-E), was performed to differ ent plant genetic backgrounds and followed by the histochemical GUS as says. The results showed that there were GUS activities expressed in t omato (Lycopersicon esculentum), tobacco (Nicotiana tabacum) and datur a (Datura stramonium), as host plants. While in non-host plants, the G US activities were observed in faba bean (Vicia faba) and squash (Cucu rbita pepo), as examples of dicot plants, but not in maize (Zea mays) as a representative of monocote.