Inheritance of Resistance to Loose and Covered Smuts in Oat Hybrids¹

Abstract

R ESULTS on the inheritance of smut resistance in crosses between Mar kton and certain other oat varieties were reported in a previous paper. 3 Markton is very resistant to the specialized races of both loose smut (Ustilago avenae (Pers.) Jens.) and covered smut (U. levis (K. and S.) Magn.), that have been used by the senior author in his experiments. Of the other varieties used as parents, Canadian, Early Champion, and Victor are susceptible to both smuts, Gothland is susceptible to loose smut but resistant to covered smut, while Monarch is resistant to loose smut and susceptible to covered smut. Results with eight additional hybrids are presented in the present paper. These may be classified into three groups, based on the reaction of the parental varieties to the specific physiologic races of the loose and covered smuts. MATERIALS AND METHODS Group r involved crosses of the variety Victor, susceptible to both smuts, with Seizure and Scottish Chief susceptible to loose smut but resistant to covered smut. Group 2 involved crosses of five varieties susceptible to loose smut and resistant to covered smut with Monarch, which is susceptible to covered smut but resistant to loose smut. These five varieties crossed with Monarch are Gothland, Rossman, Danish, Seizure, and Scottish Chief. Group 3 consisted only of the Danish Island X Monarch cross. Danish Island is very susceptible to loose smut and but slightly susceptible to covered smut. The history of these crosses is the same as for those reported in the previous paper, 4 and the specialized races of the smuts and methods of inoculation are identical. Data were obtained for the F ,, F 3 , and F 4 , and, in some cases, on the F 5 generations, but those for the F 4 and F 5 generations are omitted in this paper. EXPERIMENTAL DATA The data for the parental varieties and those obtained for the F, generation. are given in Table I. The parental varieties, Danish, Danish Island, Gothland, Rossman, Seizure, and Victor, have shown from 89.9 to 96.o% infection with loose smut. Scottish Chief has not shown so high a degree of susceptibility, as only an average of 55-S% of infection with loose smut was obtained. An infection above 75% has never been secured in the many experiments with Scottish Chief. Monarch, on the other hand, has shown a high degree of resistance to this smut, and only 0.4% of the inoculated plants were infected. 1 The investigations reported herein were conducted by the Division of Cereal Crops and Diseases, Bureau of Plant Industry, U.S. Dept. of Agriculture, in cooperation with the Brooklyn Botanic Garden, Brooklyn, N. Y. Brooklyn Botanic Garden Contribution No. 81.

Virulence of collections ofUstilago avenaeandUstilago kollerisampled from oat fields in Canada during 1995-19991

“…The cultivars AC Medallion, AC Assiniboia, AC Belmont, and AC Preakness are assumed to have the Markton resistance based on their pedigree (D. Brown, Cereal Research Centre, personal communication). Virulence on the Markton resistance genes (Markton may carry three genes for resistance; Murphy and Coffman 1961;Reed and Stanton 1938) has been reported only once from Oregon (Smith and Bressman 1931). Cultivar AC Lotta was also resistant to all but one oat smut collection from 1995-1999 (Table 1).…”

“…Roussel}] of oat (Avena sativa L.) are controlled through the widespread utilization of resistant cultivars and fungicide seed treatments (Thomas 1995). The highly effective resistance in most oat cultivars grown in western Canada is derived from Markton, which may carry three genes for resistance (Reed and Stanton 1938;Murphy and Coffman 1961). Until 1996, carbathiin was the only fungicide active ingredient registered for use as a seed treatment on oats in Canada.…”

Virulence of 1990-1994 collections ofUstilago avenaeandU. kollerifrom Manitoba and Saskatchewan

“…357-1) in the early 1920s] was a selection from an unnamed Turkish line (Holton & Murphy 1966) and may carry three genes for resistance (Murphy & Coffman 1961). Studies by Reed and Stanton (1938) suggested that resistance to U. avenae in Markton is determined by two genes, while resistance to U. kolleri is determined by one gene. They did not determine if the gene for resistance to U. kolleri was the same as one of the genes for resistance to U. avenae.…”