Inheritance of dicamba resistance in wild mustard (Brassica kaber)

By: Jasieniuk, M., I. N. Morrison, and A. L. Brule Babel.

The inheritance of resistance to dicamba in wild mustard (Brassica kaber [Sinapis arvensis]) was determined by making reciprocal crosses between a resistant (R) population, derived from a field near Gilbert Plains, Manitoba, treated repeatedly with auxin-type herbicides, and a known susceptible (S) population from Minto, Manitoba. The resulting F1 hybrids were selfed to produce F2 populations and backcrossed to the S parent. At the three- to four-leaf stage, parental, F1, F2 and backcross populations were screened for resistance to dicamba at three dosages (50, 200 and 400 g ai ha-1). F1 progeny survived all dosages and exhibited levels of injury similar to the R parental population. F2 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 F1, F2 and backcross populations to treatment with dicamba indicated that resistance is determined by a single, completely dominant nuclear allele.


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