|Cruz, Von Mark|
Submitted to: Plant Genetic Resources Newsletter
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2007
Publication Date: 6/1/2008
Citation: Cruz, V.V., Rife, C.L., Nason, J.D., Brummer, E.C., Gardner, C.A. 2008. Measuring the effectiveness of isolation of Brassica napus l. accessions during caged germplasm regeneration. Plant Genetic Resources Newsletter. 154:14-19. Interpretive Summary: Genes can be dispersed from one population (genetic group) of plants to another by movement of pollen. The result of pollination by pollen from a different population and subsequent incorporation of genes into the recipient population is called ‘geneflow.’ The mission of a germplasm bank is to maintain the original genetic profile of the accessions, or varieties, held in the collection. The North Central Regional Plant Introduction Station conserves multiple species of Brassica napus germplasm. The experiment was designed to determine whether the methods of caging each accession and using insect pollinators during regeneration were successful in preventing pollen flow from adjacent cages which would result in contamination, or geneflow. Results indicate that the regeneration methods employed at the NCRPIS for Brassica napus are suitable for controlling external contamination, thus ensuring that regeneration methods are sufficient to preserve the original genetic profile of these plant genetic resources. This research impacts researchers and breeders who need to use the same varieties over a period of decades, and must have samples that are "true-to-type" available for their research.
Technical Abstract: At the North Central Regional Plant Introduction Station (NCRPIS), screen cages and pollinator insects are used during Brassica germplasm regeneration to control outcrossing among accessions and enable the plants inside a cage to intermate. Previous reports on B. napus indicated that both insect and wind pollination occur under open field conditions. This study was conducted to determine whether current germplasm-regeneration methods prevent viable pollen of external origin from entering adjacent caged plots and contaminating Brassica napus regenerations. A dominant herbicide-resistance trait, Roundup-Ready® (RR), was chosen to detect the frequency of progeny resulting from cross pollination of plants in adjacent cages by an external pollen source because of ease of bioassay methods. A caged field was established where a non-transgenic B. napus variety was planted in two replicates surrounded by a transgenic RR isoline. Pollen escape was detected and quantified by using pollen traps placed outside the cages during the first two weeks of flowering. There was no significant correlation between pollen count and wind speed or direction. Bioassays of the progenies from the non-transgenic variety indicated that pollen flow and contamination between cages did occur, but at a very low frequency, 0.01%. These results indicate that the regeneration methods employed at the NCRPIS for B. napus are suitable for controlling external contamination.