The location and effects of genes modifying the response of wheat to the herbicide difenzoquat

Abstract

SUMMARYSingle chromosome substitution lines of hexaploid wheat were developed using a variety resistant to difenzoquat, Chinese Spring, as donor and a susceptible variety, Sicco, as recipient, and were used to identify chromosomes carrying genes which modify the responses of these varieties. It was found that chromosomes 3B and 5D from Chinese Spring might act to reduce the amount of damage caused by the herbicide in the presence of the allele for susceptibility at the Dfql locus. The intermediate response to the herbicide, which is shown by some commerical varieties, was also investigated using a backcross reciprocal monosomic analysis. In these varieties, the allele at the Dfql locus determining the reaction to the herbicide was shown to be similar to that of the susceptible variety Sicco. It is, therefore, probable that the responses of intermediate varieties are due to the effects of modifier genes increasing resistance.