VIEW ARTICLE

Genetics

Interactions of Temperature and Time with Some Puccinia recondita:Triticum Corresponding Gene Pairs. L. E. Browder, Research plant pathologist, U.S. Department of Agriculture, Agricultural Research Service, Department of Plant Pathology, Kansas State University, Manhattan 66506; M. G. Eversmeyer, Research plant pathologist, U.S. Department of Agriculture, Agricultural Research Service, Department of Plant Pathology, Kansas State University, Manhattan 66506. Phytopathology 76:1286-1288. Accepted for publication 6 May 1986. 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, 1986. DOI: 10.1094/Phyto-76-1286.

Three near-isogenic lines of Triticum aestivum, each with Lr1, Lr16, or Lr17, and their recurrent parent, Thatcher, were inoculated with two Puccinia recondita cultures, one known to be avirulent and the other virulent to the near-isogenic lines. Both cultures were virulent to Thatcher. The cultures were known to be avirulent and virulent from previous tests at continuous 20 C. These materials were exposed to four temperature regimes consisting of a varying initial period at 20 C followed by a period at 5 C for the remainder of the postinfection period. Exposures of 0, 2, 4, and 8 days at 20 C were made before transfer to 5 C. This experimental design provided a check system for the effects of host genotype, parasite genotype, temperature, and time at temperature on infection type. The data obtained indicated that Lp1/Lr1 functions during the first 2 days at 20 C, Lp17/Lr17 functions during the period from 2 to 4 days at 20 C, and Lp16/Lr16 functions during the period from 4 to 8 days after infection at 20 C. Under continuous 5 C, none of the three corresponding gene pairs functioned optimally to produce their characteristic low infection types. These data indicate that different corresponding gene pairs have different temperature ranges in which they function optimally to produce the characteristic low infection type and that different corresponding gene pairs function in different time periods.