Inheritance of Dicamba Resistance in Wild Mustard (<i>Brassica kaber</i>)

Abstract

The inheritance of resistance to dicamba in wild mustard was determined by making reciprocal crosses between a resistant (R) population derived from a field treated repeatedly with auxin-type herbicides, and a known susceptible (S) population. The resulting F 1 hybrids were selfed to produce F 2 populations and backcrossed to the S parent. At the three- to four-leaf stage, parental, F 1 , F 2 , and backcross populations were screened for resistance to dicamba at three dosages (50, 200, and 400 g ai ha −1 ). F 1 progeny survived all dosages and exhibited levels of injury similar to the R parental population. F 2 populations segregated in a 3:1 ratio of R to S phenotypes. Progeny of backcrosses segregated in a 1:1 (R:S) ratio. Responses of the F 1 , F 2 , and backcross populations to treatment with dicamba indicate that resistance is determined by a single, completely dominant nuclear allele.