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Reduced Receptivity to Infection Associated with Wheat Gene Lr2c for Low Reaction to Puccinia recondita. R. S. Modawi, U.S. Department of Agriculture, ARS, Dept. of Plant Pathology, Kansas State University, Manhattan 66506, former graduate student, Department of Agronomy, Present address: Faculty of Science and Technology, University of Gezira, P.O. Box 20, Wad Medani, Sudan; L. E. Browder(2), and E. G. Heyne(3). (2)Research plant pathologist, U.S. Dept. of Agriculture, Agricultural Research Service, Kansas State University, Manhattan, 66506; (3)Professor emeritus, Department of Agronomy, Kansas State University, Manhattan, 66506. Phytopathology 75:573-576. Accepted for publication 27 November 1984. 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, 1985. DOI: 10.1094/Phyto-75-573.

Tests were made to determine if Lr genes in wheat (Triticum aestivum) influenced the number of uredinia produced by virulent cultures of Puccinia recondita. Near-isogenic wheat lines, having genes Lr1, Lr2c, or Lr3a singly or in various combinations, and their recurrent parent were compared for receptivity to infection. We found that virulent cultures produced as many uredinia with lines having Lr1 or Lr3a as with their recurrent parents. Wheat lines having Lr2c produced fewer uredinia than their recurrent parents when inoculated with some virulent cultures, but not when inoculated with other virulent cultures. Preliminary test results revealed differences between lines having Lr2c and the recurrent parent; at 15, 20, and 25 C, significantly fewer uredinia were produced with lines having Lr2c. These results are similar to those reported by others in that not all of the specific genes tested could be shown to have a residual effect on quantitative aspects of infection. Others have reported that some virulent cultures overcome the residual effect of specific genes, but have not emphasized this aspect of their results. These results indicate that genetic interactions other than those responsible for low or high infection type may affect the number of uredinia produced in these materials.