Journal of Vzrological Methods, 42 (1993) 227-240 Q 1993 Elsevier Science Publishers B.V. / All rights reserved / 0166-0934/93/$06.00 227 VIRMET 01474 Transfection of whole plants from wounds inoculated with Agrobacterium tumefaciens containing cDNA of tobacco mosaic virus Thomas H. Turpena,b, Ann M. Turpena,b, Nicole Weinzettla, Monto H. Kumagaia and William 0. Dawsonb “Bzosource Genetics Corporation, Vacaville, CA (USA) and bDepartment of Plant Pathology, University of California, Riverside, CA (USA) (Accepted 13 November 1992) zyxwvutsrqponmlkjihgfedcbaZYXWV Summary We engineered cDNA of tobacco mosaic tobamovirus (TMV) into Agrobacterium tumefaciens for inoculation of plant cells. The resulting bacterial strains were used to transfect tobacco (Nicotiana tabacum cv. Xanthi and Xanthi/nc) with wild type and a defective virus. Lesion formation on Xanthi/nc tobacco was used to measure the timing and efficiency of transfection. Infections mediated by Agrobacterium produced lesions an average of two days later than infections produced by inoculation with virions. The addition of - 80 bp of non-viral sequences to the S-end of TMV transcripts abolished transfection. Transcripts with non-viral sequences at the 3’-end initiated infections, while precise transcript termination with a synthetic ribozyme sequence increased transfection frequencies two-fold. Culture conditions reported to induce genes of the vir region of the Agrobacterium Ti plasmid also increased the transfection frequency approximately two-fold. Therefore, in addition to the pararetroviruses and geminiviruses previously described, ‘agroinoculation’ may be used to infect plants with plus-sense RNA viruses. Agroinoculation; Agroinfection; Plus-sense RNA virus Correspondence to: Thomas H. Turpen (Blosource Genetics Corp., 3333 Vaca Valley Parkway, Vacavllle, CA 95688. USA. Present address. W.O. Dawson, University of Flonda, CREC. 700 Experiment Statlon Road, Lake Alfred, FL 33850, USA.