Citrus paradisi Macfad. ‘Duncan’ was transformed with constructs coding for the wild-type and mutant RNAdependent RNA polymerase (RdRp) of Citrus tristeza virus (CTV) for exploring replicase-mediated pathogen-derived resistance (RM-PDR). | B. ÇEVİK, R. F. LEE, C. L. NIBLETT Research Article Turk J Agric For 36 (2012) 195-206 © TÜBİTAK doi: Agrobacterium-mediated transformation of grapefruit with the wild-type and mutant RNA-dependent RNA polymerase genes of Citrus tristeza virus Bayram ÇEVİK1,*, Richard F. LEE2, Charles L. NIBLETT3 1 Department of Plant Protection, Faculty of Agriculture, Süleyman Demirel University, 32260 Isparta - TURKEY 2 USD-ARS National Clonal Germplasm Repository for Citrus and Dates, Riverside, CA 92521 - USA 3 Venganza, Inc., Raleigh, NC 27606 - USA Received: Abstract: Citrus paradisi Macfad. ‘Duncan’ was transformed with constructs coding for the wild-type and mutant RNAdependent RNA polymerase (RdRp) of Citrus tristeza virus (CTV) for exploring replicase-mediated pathogen-derived resistance (RM-PDR). The RdRp gene was amplified from a CTV genome and used to generate the wild-type and 2 mutant RdRp constructs for plant transformation. One mutant had the key amino acids GDD changed to AAA (RdRpmGDD), and the second mutant had a deletion encompassing the GDD domain (RdRp-ΔGDD). Etiolated epicotyl segments of Duncan grapefruit (Citrus paradisi Macfad. ‘Duncan’) were transformed with each of these constructs using the Agrobacterium-mediated transformation method. From 4540 transformed epicotyl segments, 1402 kanamycinresistant shoots were regenerated. After testing for expression of green fluorescent protein (GFP) and β-glucuronidase (GUS) reporter genes by fluorescence microscopy and histochemical staining, respectively, 146 GUS-positive plants were rooted and 97 surviving plants were established in soil in pots. A total of 70 plants were tested for the presence of the GUS gene and CTV RdRp transgenes by polymerase chain reaction (PCR). A total of 51 GUS and CTV transgenepositive transgenic plants (15 with RdRp, 21 with RdRp-mGDD, and 15 with RdRp-ΔGDD) were identified. Key words: Citrus tristeza virus, plant transformation, .
