Medicago truncatula, a model plant for studying the molecular genetics of the Rhizobium-legume symbiosis

Abstract

Medicago truncatula has all the characteristics required for a concerted analysis of nitrogen-fixing symbiosis with Rhizobium using the tools of molecular biology, cellular biology and genetics. M. truncatula is a diploid and autogamous plant has a relatively small genome, and preliminary molecular analysis suggests that allelic heterozygosity is minimal compared with the cross-fertilising tetraploid alfalfa (Medicago sativa). The M. truncatula cultivar Jemalong is nodulated by the Rhizobium meliloti strain 2011, which has already served to define many of the bacterial genes involved in symbiosis with alfalfa. A genotype of Jemalong has been identified which can be regenerated after transformation by Agrobacterium, thus allowing the analysis of in-vitro-modified genes in an homologous transgenic system. Finally, by virtue of the diploid, self-fertilising and genetically homogeneous character of M. truncatula, it should be relatively straightforward to screen for recessive mutations in symbiotic genes, to carry out genetic analysis, and to construct an RFLP map for this plant. © 1990 Kluwer Academic Publishers.