Observed segregation for reaction to stem rust in several oat crosses was on a monohybrid basis except in the cross Sac x Hajira-Joanette where segregation was observed to be on a three-factor basis. A mesothetic type of reaction to the composite of races 2 and 8 was observed in seedling plants classified as susceptible in two crosses, Mindo x Tama and Sac x Hajira-Joanette. Since no segregation was observed for reaction to race 2 in either of the two crosses, one factor pair for resistance to race 8 must be allelic to the one governing resistance to race 2 possessed by Tama and Hajira x Joanette.
Segregation for reaction to races 1 and 45 of crown rust was on a monogenic, digenic or trigenic basis in different crosses investigated. Five different factors for resistance to crown rust were identified in this study: A and B, complementary dominant factors which give the Bond type (type 0) of resistance of race 1; L, a simple dominant which gives the Landhafer type of resistance (type 0-1) to races 1 and 45; S, a simple dominant from Santa Fe which governs resistance (type 0) to races 1 and 45; and V, a simple dominant of the hypersensitive type (type 2) from Victoria which also governs resistance to races 1 and 45. The factor from Santa Fe (S) appears to be of great promise as a source of resistance to the relatively prevalent race 45. Many desirable agronomic progenies possessing resistance to races 1 and 45 from the cross of Santa Fe x Clinton have been selected for further testing. Very few selections have been made from Mindo x Landhafer for testing in F4. The L factor does not appear to be too satisfactory under the conditions of this experiment for resistance in the mature plant stage.
Litzenberger, S. C.
"Inheritance of resistance to specific races of crown and stem rust, to Helminthosporium blight, and of certain agronomic characters of oats,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 29
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol29/iss370/1