Development of Triazine Resistance in Crops by Classical Plant Breeding

Abstract

The appearance of triazine resistance in a number of weed species has provided some opportunities for plant breeders to develop triazine-resistant crop varieties through classical breeding techniques. The sources of genes utilized by plant breeders for desirable characteristics are usually limited by the normal reproductive barriers that distinguish species. The occurrence of a triazine-resistant biotype of birdsrape mustard (Brassica campestris L. # BRSRA) has allowed for the development of commercially useful triazine-resistant varieties of canola (low erucic acid, low glucosinolate oilseed rape, B. napus L.). The cytoplasm of triazine-resistant birdsrape mustard was transferred interspecifically to oilseed rape, by a technique commonly known as back-crossing, in conjunction with selection for chromosome number. ‘OAC Triton′, the first triazine-resistant canola variety, appears to be finding commercial acceptance in Canada, in spite of some limitations in agronomic performance. Although it should be possible to transfer this triazine-resistant cytoplasm to other economic Brassica species including the cole crops and mustards, conventional plant breeding techniques cannot separate the gene conferring triazine resistance from other genes in the resistant weed biotype's cytoplasm. This problem may limit the utility of triazine-resistant cytoplasms from weed biotypes in classical crop breeding.