Interactions of Temperature and Time with SomePuccinia recondita:TriticumCorresponding Gene Pairs

Abstract

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 virulent and the other virulent to the near-isogenic lines. Both cultures were virulent to Thatcher. The cultures were known to be virulent and virulent from previous studies at continuous 20 C. These materials were exposed to four temperature regimes consisting of 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 chick 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 t 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 correspond 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 times periods.