Correlation between Resistance to Stem Rust and the Concentration of a Glucoside in Wheat

Abstract

THE presence of 2-O-glucosyl-2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one in wheat was demonstrated by Virtanen¹ and by ElNaghy and Linko². The latter reported higher concentrations of this glucoside in Khapli and Justin wheats, which are resistant to most races of stem rust, than in Little Club and other susceptible varieties. We have measured the concentrations of the glucoside in the primary leaves of five of the so-called differential varieties of wheat with varying degrees of rust resistance (Little Club, Acme, Kubanka, Mindum and Khapli) and have found that there is a significant negative correlation between glucoside content and the number of races of stem rust to which each variety is susceptible. We have also found that the glucoside content of Kenya 58-Marquis¹⁰ (produced by back-crossing a Kenya 58-Marquis hybrid to Marquis nine times³) is correlated with its resistance to race 15B of Puccinia graminis tritici Erikss. and Henn. This line of wheat carries the temperature sensitive gene Sr6 and is resistant to race 15B at 62° F and susceptible at 79° F (ref. 4).