Inheritance of Reaction to Stem and Leaf Rust in Winter Wheat Crosses

Inheritance of seedling resistance to race 2 of leaf rust and races 15B-2 and 32B of stem rust was studied in the variety Greece 78310-a-3, at University of Nebraska greenhouses, Lincoln, Nebraska.Winter wheat crosses were investigated to determine whether they possess genes for resistance that may be useful in a breeding program, as shown by their reactions to those currently important races.Segregations of resistant x susceptible crosses and between resistant varieties were analyzed against expected ratios of genetic hypotheses by the chi-square goodness-of-fit test. Greece 78310-a-3 was found to carry one single gene for leaf rust (race 2) resistance.Inoculations with race 15B-2 of stem rust indicated that the resistance is also conditioned by one gene, which is at the same locus in NB 66490 and NB 66403 (probably Sr6). Monohybrid inheritance of reaction to race 32B of stem rust occurred in the crosses involving Greece 78310-a-3.This gene for resistance to race 32B was susceptible to temperature variation. Resistance proved to be dominant for all races tested. Advisor: John W. Schmid