Relationship Between Resistance toMeloidogyne incognitaand a Necrotic Response to Infection by a Strain of Potato Virus Y in Tobacco

Publisher Website
Google Scholar
Abstract
Cultivars of N. tabacum resistant to the root-knot nematode, M. incognita, develop vascular necrosis when infected by strain MSNR of potato virus Y (PVY-MSNR). Young (2-8 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 (17-30 cm tall), virus-induced necrosis was severe at 28.degree. C, mild at 32.degree. C, and absent at 35.degree.-40.degree. C. The same temperature which inhibited the expression of root-knot resistance also inhibited the necrotic response to PVY-MSNR. 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-MSNR suggests that the basis for the association of these 2 responses may be due to pleiotropic effects of a single gene.