title: Genetic transformation of western clover (Trifolium occidentale D. E. Coombe.) as a model for functional genomics and transgene introgression in clonal pasture legume species.
abstract: BACKGROUND
  Western clover (Trifolium occidentale) is a perennial herb with characteristics compatible for its development as an attractive model species for genomics studies relating to the forage legume, white clover (Trifolium repens). Its characteristics such as a small diploid genome, self-fertility and ancestral contribution of one of the genomes of T. repens, facilitates its use as a model for genetic analysis of plants transformed with legume or novel genes.
  
  
  RESULTS
  In this study, a reproducible transformation protocol was established following screening of T. occidentale accessions originating from England, Ireland, France, Spain and Portugal. The protocol is based upon infection of cotyledonary explants dissected from mature seed with the Agrobacterium tumefaciens strain GV3101 carrying vectors which contain the bar selection marker gene. Transformation frequencies of up to 7.5% were achieved in 9 of the 17 accessions tested. Transformed plants were verified by PCR and expression of the gusA reporter gene, while integration of the T-DNA was confirmed by Southern blot hybridisation and segregation of progeny in the T1 generation.
  
  
  CONCLUSIONS
  Development of this protocol provides a valuable contribution toward establishing T. occidentale as a model species for white clover. This presents opportunities for further improvement in white clover through the application of biotechnology.
authors.affiliation: AgResearch Ltd, Grasslands Research Centre, Private Bag 11008, Palmerston North 4442, New Zealand. kim.richardson@agresearch.co.nz.
authors.forename: Kim A
authors.initials: KA
authors.lastname: Richardson
authors.forename: Dorothy A
authors.initials: DA
authors.lastname: Maher
authors.forename: Chris S
authors.initials: CS
authors.lastname: Jones
authors.forename: Greg
authors.initials: G
authors.lastname: Bryan