Genetic Resistance to Tobacco Mosaic Virus, Cyst Nematodes, Root-Knot Nematodes, and Wildfire from Nicotiana repanda Incorporated into N. tabacum. G. R. Gwynn, Research Agronomist, USDA, ARS, Tobacco Research Laboratory, Oxford, NC 27565. K. R. Barker, Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695; J. J. Reilly and D. A. Komn, Former Assistant Professors, Department of Plant Pathology, Virginia Polytechnic Institute and State University, Southern Piedmont Research Center, Blackstone; L. G. Burk, Research Geneticist, Retired, USDA, ARS, Oxford, NC 27565; and S. M. Reed, Assistant Professor, Department of Crop Science, North Carolina State University, Raleigh 27695. Plant Dis. 70:958-962. Accepted for publication 21 March 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-958.

Nicotiana repanda was crossed as the female with N. tabacum, using the bridge-cross technique with N. sylvestris as the intermediary species. The resulting material was backcrossed to N. tabacum cultivars and screened for tobacco mosaic resistance. Pollen infertility was overcome by the use of a pollen fertility restorer, which allowed the test material to be used as a male with the subsequent elimination of N. repanda cytoplasm. Breeding material with the local-lesion type of hypersensitive response to tobacco mosaic virus was obtained from N. repanda. Segregation was unpredictable and chromosome instability was indicated. Frequency of resistance was increased through subsequent backcrossing. Other breeding material from the same crosses indicated the possibility of obtaining resistance to the pathogens Meloidogyne incognita, Globodera tabacum solanacearum, and Pseudomonas syringae pv. tabaci.

Keyword(s): interspecific, hybridization, tobacco diseases.