VIEW ARTICLE

Resistance

Relationship Between Resistance to Meloidogyne incognita and a Necrotic Response to Infection by a Strain of Potato Virus Y in Tobacco. Rebeca C. Rufty, Research associate, Department of Plant Pathology, North Carolina State University, Raleigh 27650; N. T. Powell(2), and G. V. Gooding, Jr.(3). (2)(3)Professors, respectively, Department of Plant Pathology, North Carolina State University, Raleigh 27650. Phytopathology 73:1418-1423. Accepted for publication 2 May 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1418.

Cultivars of Nicotiana tabacum resistant to the root-knot nematode, Meloidogyne incognita, develop vascular necrosis when infected by strain M^SN^R of potato virus Y (PVY- M^SN^R). Young (2- to 8-cm tall) root-knot-resistant plants were more susceptible to the virus than older plants and developed necrosis under all aerial and soil temperatures tested. In older plants (17- to 30-cm tall), virus-induced necrosis was severe at 28 C, mild at 32 C, and absent at 35- 40 C. The same temperature which inhibited the expression of root-knot resistance also inhibited the necrotic response to PVY-M^SN^R. The necrotic reaction to the virus was specific to root-knot resistant genotypes and did not translocate to root-knot susceptible genotypes when various combinations of these genotypes were grafted. Root-knot susceptible plants developed mild, vein-banding symptoms but no necrosis, and virus reaction was not significantly affected by plant age or temperature. The similarity in temperature sensitivity involved in both root-knot resistance and the necrotic reaction elicited by PVY-M^SN^R suggests that the basis for the association of these two responses may be due to pleiotropic effects of a single gene.