Genetic Basis of Dinitroaniline Herbicide Resistance in a Highly Resistant Biotype of Goosegrass (Eleusine indica)

The inheritance of dinitroaniline herblcide resistance was investigated based on the dinitroaniline response phenotype of F1 plants and segregation analysis in F2 and F3 progenies. Reciprocal crosses were made between two susceptible (S) blotypes and two resistant (R) biotypes. Seven F1 hybrids were identified by isoenzyme analysis, and F2 and F3 populations were derived from these F1 plants by selfing. The dinitroaniline response phenotype of F1 plants and F2 and F3 seedlings was determined using a root growth bloassay. F1 plants were phenotypically susceptible (i.e., Identical to their S parental plants), indicating that resistance is recessive to susceptibility. Nonparental phenotypes were not observed, and data from reciprocal crosses gave no indication of maternal or paternal inheritance. F2 seedlings were classified as either S or R phenotype. The observed segregation ratio of S to R seedlings fit only a 3:1 (S:R) ratio. Segregation data indicated the dinitroaniline herbicide-response phenotype is inherited as a single nuclear gene, and it identified two alleles (i.e., Drps and Drpr) at this single locus. The 3:1 segregation ratio was confirmed by analysis of F3 progenies. Taken together, results from F1, F2 and F3 plants were consistent with dinitroaniline herbicide resistance being inherited as a single, recessive nuclear gene.