To study the effect of incubation time and temperature on the phenotypic expression of rpg4, five barley genotypes with this
resistance gene were infected with pathotype QCCJ of Puccinia graminis f. sp. tritici at the seedling stage, then subjected to various
times of incubation at either 18-19°C or 27~28°C. Genotypes with rpg4 exhibited low (0, 0;, and 1), mesothetic (e.g.
3-210;, 120;3), and high (3,3) infection types at 18-19°C after initial incubation at 27-28°C for 0-28, 40-76, and 88 or more
hours, respectively. A period of 88 or more hours of initial incubation at high temperature rendered the rpg4 resistance completely
ineffective against this pathotype of P. g. f. sp. tritici. In contrast, high, mesothetic, and low infection types were found
for the same genotypes at 27-28°C after initial incubation at 18-19°C for 0-40, 52-100, and 112 or more hours, respectively.
The resistant infection types conferred by rpg4 are apparently established within the first 112 hours after the end of the infection
period since subsequent shifts to higher temperature did not result in marked changes in the resistance response. These data indicate
the critical importance of maintaining precise temperature control when assessing the infection phenotypes of barley genotypes
carrying the stem rust resistance gene rpg4.
Sun, Y., & Steffenson, B. (1997). Effect of incubation time and temperature on the phenotypic expression of rpg4 to Puccinia graminis f. sp. tritici in barley. Canadian Journal of Plant Pathology, 19(1), 25-29.
Canadian Journal of Plant Pathology website: http://www.tandfonline.com/loi/tcjp20
Sun, Yonglian; Steffenson, Brian.
Effect of incubation time and temperature on the phenotypic expression of rpg4 to Puccinia graminis f. sp. tritici in barley.
Canadian Journal of Plant Pathology.
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