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Resistance

Inheritance of Resistance to Lettuce Mosaic Virus in Safflower. C. A. Thomas, Applied Plant Pathology Laboratory, Plant Protection Institute, Science and Education Administration, U.S. Department of Agriculture, Beltsville, MD 20705; Phytopathology 71:817-818. Accepted for publication 24 December 1980. 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, 1981. DOI: 10.1094/Phyto-71-817.

The safflower cultivar LMVFP-1 possesses a high level of resistance to lettuce mosaic virus (LMV). Mechanical inoculation of either young or adult plants differentiated the high level of resistance from lower levels. A mild, nonlethal form of systemic necrosis that developed subsequent to local lesions was characteristic of high resistance. The reactions of the F₁, F₂, and BC₁ progenies derived from crosses between LMVFP-1 and a mosaic-susceptible cultivar, and between LMVFP-1 and a cultivar that developed local lesions and severe systemic necrosis, indicate that the local lesion reaction is conditioned by a single dominant gene, and that the recessive allele conditioning the mosaic reaction is epistatic to a second independently dominant gene that conditions the mild vs systemic necrosis reaction.