Agrobacterium tumefaciens-mediated Transformation of Double Haploid Canola (Brassica napus) Lines

Abstract

Double haploid (DH) genotypes of canola (Brassica napus L.) have a high level of genetic uniformity but have not been previously tested for genetic transformation. Transgenic plants from three of four DH genotypes derived from cv. Westar were obtained by inoculation of either hypocotyl segments or root explants with Agrobacterium tumefaciens. For hypocotyl transformation, A. tumefaciens strain LBA4404 containing a binary plasmid with the neomycin phosphotransferase gene (nptII) and a CaMV 35S-peroxidase gene cassette was co-cultivated with hypocotyl segments taken from the 5–6-day-old seedlings. Transformation frequencies for hypocotyl explants of two DH genotypes were 0.3–3%. Direct evidence for genetic transformation of hypocotyl explants was obtained through molecular hybridisation analysis. Using this protocol, mature transformed plants were obtained within 4–6 months of co-cultivation. A method of root transformation was successfully modified for one DH genotype of canola and transgenic plants were obtained at a frequency of 2%. Using this protocol, a peroxidase gene promoter–GUS fusion construct was introduced into a DH genotype. Tissue specific GUS expression driven by the peroxidase gene promoter in transgenic plants was analysed by GUS staining. Transformation systems for double haploid canola lines will permit the assessment of introduced genes for their effect on agronomic and physiological traits.