Insertional mutagenesis: a Swiss Army knife for functional genomics of Medicago truncatula.

Legumes are second only to grasses in worldwide economic importance, and understanding their molecular genetics is vital to the breeding of important grain and forage legumes. Over the past decade, Medicago truncatula has been selected as a model plant in which to study biological processes that are unique and pertinent to legumes, and that cannot easily be studied in Arabidopsis. Here, we discuss the most common tools for introducing and analyzing genetic mutations in M. truncatula. Because transformation and regeneration are still bottlenecks in studying a legume species, large-scale insertional mutagenesis poses a major challenge in M. truncatula. We discuss the tobacco retrotransposon Tnt1 as a viable and attractive option for introducing multiple independent insertions per plant for saturation mutagenesis.