Identification of putative quantitative trait loci associated with a flavonoid related to resistance to cabbage seedpod weevil (Ceutorhynchus obstrictus) in canola derived from an intergeneric cross, Sinapis alba × Brassica napus.

KEY MESSAGE: Kaempferol 3- O -sinapoyl-sophoroside 7- O -glucoside was putatively identified as the major component of a characteristic HPLC peak previously correlated with the reduction of cabbage seedpod weevil larval infestation in a novel canola genotype. The cabbage seedpod weevil (Ceutorhynchus obstrictus [Marsham]) (CSPW) is a serious pest of brassicaceous oilseed crops such as canola in both Europe and more recently in North America. At present, the only control strategy against CSPW is the application of insecticides. As an alternative more environmentally-friendly control strategy, we developed novel canola germplasm resistant to weevil attack through introgression of Sinapis alba DNA into Brassica napus by making the wide cross followed by embryo rescue and backcrossing to the B. napus parent. We have previously characterized resistant canola lines by metabolic profiling and were able to correlate reduction of larval infestation to the presence of a characteristic HPLC peak. In this study, we have putatively identified the major component in the peak using mass spectrometry as kaempferol 3-O-sinapoyl-sophoroside 7-O-glucoside (KSSG). We have also identified quantitative trait loci (QTL) associated with this HPLC peak in a mapping population consisting of more than 200 individual doubled haploid (DH) lines derived from a cross between CSW428 (the resistant parent) and SC030686 (the susceptible parent). This QTL accounted for approximately 9.5 % of the phenotypic variation in KSSG content. The observation that only one QTL was identified as surpassing the LOD threshold of 3.0 suggests that both parents may possess the positive alleles for other QTL that have not been detected in our study. This finding also indicates a complex regulatory mechanism for KSSG levels and provides an appropriate explanation for the large transgressive segregation observed in the DH lines of the QTL mapping population.

Expression of a modified Mannheimia haemolytica GS60 outer membrane lipoprotein in transgenic alfalfa for the development of an edible vaccine against bovine pneumonic pasteurellosis.

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.