VIEW ARTICLE

The Effect of Temperature and Genetic Background on Host Gene Expression and Interaction to Puccinia graminis tritici. N. H. Luig, Senior Research Fellow, Department of Agricultural Botany, University of Sydney, New South Wales, Australia 2006; S. Rajaram, Postgraduate Student, Department of Agricultural Botany, University of Sydney, New South Wales, Australia 2006, Present address: CIMMYT, Londres 40, Mexico 6, D.F., Mexico. Phytopathology 62:1171-1174. Accepted for publication 7 March 1972. DOI: 10.1094/Phyto-62-1171.

Infection types produced by Puccinia graminis f. sp. tritici on seedlings of near-isogenic lines of Marquis wheat, and on homozygous and heterozygous combinations between them, were studied in growth cabinets at six temperature levels. At the high temperatures, 27 and 30 C, seedlings heterozygous or homozygous for the genes Sr5, Sr8, and Sr9b became susceptible or semisusceptible. When Sr5 and Sr9b were transferred by successive backcrosses to the highly susceptible background of W2691 and W3498, the infection types became much higher, and heterozygous seedlings were semisusceptible at the intermediate temperature range. In most instances, combinations of host genes resulted in higher levels of resistance. Higher temperatures and susceptible genetic backgrounds interacted in decreasing the resistance provided by all genes.