RESUMO
Auxinic herbicides (e.g. dicamba) are extensively used in agriculture to selectively control broadleaf weeds. Although cultivated species of Brassicaceae (e.g. Canola) are susceptible to auxinic herbicides, some biotypes of Sinapis arvensis (wild mustard) were found dicamba resistant in Canada. In this research, dicamba tolerance from wild mustard was introgressed into canola through embryo rescue followed by conventional breeding. Intergeneric hybrids between S. arvensis (2n = 18) and B. napus (2n = 38) were produced through embryo rescue. Embryo formation and hybrid plant regeneration was achieved. Transfer of dicamba tolerance from S. arvensis into the hybrid plants was determined by molecular analysis and at the whole plant level. Dicamba tolerance was introgressed into B. napus by backcrossing for seven generations. Homozygous dicamba-tolerant B. napus lines were identified. The ploidy of the hybrid progeny was assessed by flow cytometry. Finally, introgression of the piece of DNA possibly containing the dicamba tolerance gene into B. napus was confirmed using florescence in situ hybridization (FISH). This research demonstrates for the first time stable introgression of dicamba tolerance from S. arvensis into B. napus via in vitro embryo rescue followed by repeated backcross breeding. Creation of dicamba-tolerant B. napus varieties by this approach may have potential to provide options to growers to choose a desirable herbicide-tolerant technology. Furthermore, adoption of such technology facilitates effective weed control, less tillage, and possibly minimize evolution of herbicide resistant weeds.
Assuntos
Brassica napus/efeitos dos fármacos , Brassica napus/genética , Dicamba/farmacologia , Tolerância a Medicamentos/genética , Desenvolvimento Vegetal/genética , Sinapis/efeitos dos fármacos , Sinapis/genética , Brassica napus/embriologia , Brassica napus/crescimento & desenvolvimento , Cruzamento , Canadá , DNA de Plantas/genética , Genes de Plantas/genética , Genoma de Planta , Herbicidas/farmacologia , Hibridização in Situ Fluorescente , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/embriologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Ploidias , Sinapis/crescimento & desenvolvimentoRESUMO
The GS60 antigen is one of the protective antigens of Mannheimia haemolytica A1. GS60 contains conserved domains belonging to the LppC family of bacterial outer membrane lipoproteins. A high antibody titer to GS60 has been shown to be significantly correlated with resistance to pneumonic pasteurellosis. Calves vaccinated with a commercial vaccine (Presponse) and demonstrating protection against M. haemolytica A1 produced antibodies directed against GS60. Alfalfa was chosen as the platform for an edible vaccine. Agrobacterium tumefaciens was used to mediate the transformation of alfalfa with sequences encoding a slightly shortened derivative of the GS60 antigen (GS60(54)). Stable transgenic alfalfa lines were recovered and production of GS60(54) was examined by Western immunoblot analysis. The antigen is stable in dried transgenic plant material stored at ambient temperature for more than a year. The plant-produced GS60(54) protein was shown to be immunogenic when injected into rabbits. Feeding of the dried transgenic alfalfa expressing the GS60(54) to rabbits is capable of inducing seroconversion, suggesting that GS60(54) could be an effective oral antigen for stimulating mucosal immune responses.