Camelina Mutants Resistant to Acetolactate Synthase Inhibitor Herbicides.

Herbicide Resistant Camelina: Adapting an Oilseed Crop to PNW Cropping Systems

Ebrahiem Babiker², Dusty Walsh¹, , Ian Burke ¹ and Scot Hulbert ^1,2  Department of Crop and Soil Sciences, ² Department of Plant Pathology, Washington State University, Pullman WA 99164-6430

Heightened interest in Biofuel crops has increased research on camelina (Camelina sativa), a small seeded oil crop that is proving to be well adapted for production in the Pacific Northwest (PNW). The use of acetolactate synthase (ALS) inhibitor herbicides in the PNW has been a barrier to camelina adoption because of its extreme sensitivity to residual activity of these herbicides in soils. The objectives of this work were to (³) develop a camelina germplasm with reduced sensitivity to these herbicides through mutation breeding. (³³) characterize the resistant gene and develop PCR markers to distinguish resistant lines from wild type lines. Camelina seeds were mutagenized by exposure to ethane methyl sulfonate (EMS). M₂ populations were planted in the field and treated with a standard field rate of imazethapyr and sulfosulfuron. One mutant, designated MM4, was identified that had increased resistance to both herbicides. Progeny from this mutant were rescreened in greenhouse with three families of ALS inhibiting herbicides. To amplify the ALS gene, one primer pair was design from regions of ALS gene sequences that were conserved between Brassica napus L. and Camelina microcarpa. Sequencing of amplified fragments found 95% and 96% similarity to ALS genes from B. napus L. and C. microcarpa. Comparative analysis of the ALS gene sequences from wild type and MM4 mutant revealed one substitution at nucleotide1474 in MM4 resulting in an amino acid change at position 578 from phenylalanine to leucine. This mutation has been observed before in yeast and tobacco and it was responsible for conferring cross resistance to ALS inhibiting herbicides. Sequence analysis of ALS genes from the MM4 identified a gene family with at least six members. A detected SNP was converted into an Xho1- dCAPS marker using the web based program dCAPS Finder 2.0