ASSOCIATED INHERITANCE OF REACTION TO RACES OF CROWN RUST, PUCCINIA CORONATA AVENAE ERIKSS., AND TO VICTORIA BLIGHT, HELMINTHOSPORIUM VICTORIAE M. AND M., IN OATS

Abstract

The oat variety Victoria has been shown by various investigators to be resistant to most races of crown rust but susceptible to a disease known as Victoria blight. This disease was observed for the first time in the United States in 1944 and in Canada in 1947. Susceptibility to this disease has been considered, by several workers, to be linked with the Victoria type of resistance to crown rust. The present investigations indicate that Victoria has more than one major gene for resistance to crown rust. These findings are based on data from a study of advanced generation selections of Victoria parentage and from inheritance studies involving varieties with the Victoria resistance to crown rust, such as Garry and R.L. 1987. Lines were obtained from Garry and from F3 populations of different crosses with the following three types of disease reactions: (1) lines susceptible to Victoria blight and resistant to all crown rust races studied, namely, races 1, 2, 3, 4, 5, 6, 24, 34, 34A. 38, 45, and 57; (2) lines resistant to Victoria blight and susceptible to crown rust races 4, 5, 34A, and 57, but resistant to the other races; (3) lines resistant to Victoria blight and susceptible to all races. Inheritance studies of three crosses, Garry × Exeter, Garry × Roxton, and Roxton × R.L. 1987, indicate that susceptibility to Victoria blight is dominant and governed by a single major gene; that resistance to races 4, 5, 34A, and 57 of crown rust is dominant and governed by a single major gene, but linked with susceptibility to Victoria blight; and that resistance to race 45, as well as races 1, 2, 3, 6. 24, 34, and 38, which appear to be similar to race 45 in inheritance, is conditioned by three dominant genes, one of which is associated, with susceptibility to Victoria blight.