VIEW ARTICLE

Resistance

Probable Source of Meloidogyne incognita Resistance in Tobacco as Indicated by Reactions to Five Meloidogyne Isolates. L. J. Slana, Plant Pathology, Support Scientist, Tobacco Laboratory, Plant Genetics and Germplasm Institute, Plant Protection Institute, Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, Present address of senior author: Graduate Student in the Department of Botany, University of Maryland, College Park, Maryland; J. R. Stavely(2), J. J. Grosso(3), and A. M. Golden(4). (2)(3)Research Plant Pathologists, respectively, Tobacco Laboratory, Plant Genetics and Germplasm Institute, Plant Protection Institute, Beltsville Agricultural Research Center, Agricultural Research Service, U. S. Department of Agriculture, Beltsville, MD 20705; (4)Research Nematologist, Nematology Laboratory, Plant Protection Institute, Beltsville Agricultural Research Center, Agricultural Research Service, U. S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 67:537-543. Accepted for publication 1 November 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-537.

Nicotiana species, an interspecific hybrid, and tobaccos that were reportedly parents of root knot-resistant tobacco, related Nicotiana lines as well as resistant N. tabacum ‘NC95’ and breeding line Bel 4-30 were inoculated with five root knot nematode isolates of the genus Meloidogyne. Resulting root knot indices indicated that the source of resistance to two of these nematodes in NC95 and Bel 4-30 is probably not tobacco introduction (T. I.) 706, as previously reported, but either N. tomentosa or perhaps N. tomentosiformis. Nicotiana tomentosa, but not N. tomentosiformis or T. I. 706, responded to each nematode almost identically to NC95 and Bel 4-30. Populations of N. otophora were highly variable in response to most of the nematode isolates and the pattern of response to the five nematode isolates eliminated this species as a possible source of the resistance in NC95 and Bel 4-30. Nicotiana otophora showed some resistance to two nematode isolates for which resistance is not now available. The results are discussed in relation to previous reports, the method by which resistance was transferred to tobacco, and their implications for future improvement of disease resistance in tobacco.