Genetics of crown rust resistance in oat

Crown rust (Puccinia coronata f, sp. avenae) is the main disease in the oat crop (Avena saliva L.) and the use of resistant cultivars is the most impo rtant control method. This study had as objective to determine the genetic control of resistance to crown rust in oat and to identify different gene s ources for resistance to this disease. Three resistant genotypes (UFRGS 15, UFRGS 881920 and UFRGS 86A1194-2), three susceptible genotypes (UFRGS 7, U FRGS 8 and UFRGS 14) and the F-3 progenies derived from crosses between the se genotypes were used. The plants were evaluated individually with regard to the presence or absence of crown rust symptoms, and the data from these evaluations were used to perform a genetic analysis in which the hypothesis of one or two resistance genes were tested by the chi-square test. Results showed one dominant resistance gene in UFRGS 881920 and two complementary resistance genes in UFRGS IS, when they were crossed with the susceptible g enotypes. The genetic analysis performed did not allow to determine whether these two genotypes are or are not the same source of resistance.