Transformation of Medicago truncatula via infiltration of seedlings or flowering plants with Agrobacterium

Two rapid and simple in planta transformation methods have been developed f or the model legume Medicago truncatula. The first approach is based on a m ethod developed for transformation of Arabidopsis thaliana and involves inf iltration of flowering plants with a suspension of Agrobacterium. The secon d method involves infiltration of young seedlings with Agrobacterium. In bo th cases a proportion of the progeny of the infiltrated plants is transform ed. The transformation frequency ranges from 4.7 to 76% for the flower infi ltration method, and from 2.9 to 27.6% for the seedling infiltration method . Both procedures resulted in a mixture of independent transformants and si bling transformants. The transformants were genetically stable, and analysi s of the T-2 generation indicates that the transgenes are inherited in a Me ndelian fashion. These transformation systems will increase the utility of M. truncatula as a model system and enable large-scale insertional mutagene sis. T-DNA tagging and the many adaptations of this approach provide a wide range of opportunities for the analysis of the unique aspects of legumes.