Specific expression of exendin-4 gene fused to cholera B toxin subunit (CTB) in carrot root (Daucus carota L.) under regulation of MLL promoter Neda Zandinava Master of Plant Biotechnology, Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran. Email address: Nedazandinava@gmail.com Bahman Bahramnejad *Corresponding author. Associate professor in Plant Biotechnology, Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran. Email address: b.bahramnejad@uok.ac.ir Hemn Salehi Ph.D. Student of Plant Biotrchnology, Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran. Email address: hemn.salehi@uok.ac.ir Abstract Objective Exendin-4 (Ex4) is a 39-amino acid peptide isolated from the salivary secretions of the lizard Heloderma susceptum and it has similar biological function as glucan-like peptide (GLP-1) receptor. The most important physiological role of GLP-1 is to regulate the amount of glucose metabolism by reducing the entry of glucose into the cells. The binding of Ex4 to cholera toxin B subunit (CTB) increases its efficacy by binding to the receptor of intestinal epithelial cells. Transgenic plants can be used as factories for the production of recombinant proteins. In order to maximize the efficiency of transgenic plants, the expression of foreign genes can be regulated in terms of time and place under the regulation of different promoters. Considering the nutritional value of carrot tuber and its fresh consumption, in this study, CTBEx4 gene was expressed in carrot plant using a root-specific promoter. In this study, in order to specifically express the CTBEx4 gene in carrot root, the Major Latex-Like promoter (MLL) related to the specific expression in sugar beet storage root tissue was replaced by the CaMV35S promoter in the pBI121 construct and were used for the transformation of carrot explants.