TRANSFORMATION OF BARREL MEDIC (MEDICAGO-TRUNCATULA GAERTN) BY AGROBACTERIUM-TUMEFACIENS AND REGENERATION VIA SOMATIC EMBRYOGENESIS OF TRANSGENIC PLANTS WITH THE MTENOD12 NODULIN PROMOTER FUSED TO THE GUS REPORTER GENE

Fertile and stable transgenic plants of the model legume Medicago trun catula Gaertn. were obtained through transformation of leaf tissue wit h the disarmed Agrobacterium tumefaciens strain LBA4404 and in vitro r egeneration via somatic embryogenesis. An optimised transformation/reg eneration protocol has been established for two genotypes of the culti var Jemalong, including a previously described highly embryogenic line (Nolan et al. 1989, Plant Cell Rep. 8: 278-281). Using this protocol, transgenic plantlets were obtained within 4-10 months following cocul tivation with Agrobacterium. We have introduced into M. truncatula a c himeric fusion between the early nodulin MtENOD12 promoter and the gus (beta-glucuronidase) reporter gene, and shown that symbiosis-specific gene expression can be elicited in the roots of such transgenic plant s following the addition of purified Rhizobium nodulation factors.