Transformation of Medicago by Agrobacterium mediated gene transfer.

Shoot segments of Medicago varia genotype A2 were co-cultivated with Agrobacterium tumefaciens strain bo42 carrying pGA471, a plasmid coding for the kanamycin resistant determinant as transferable positive selection marker in plant cells (An et al., 1985). Resistant plants were regenerated at high frequency from green calli developed on inoculated stem cuttings under kanamycin selection. DNA-DNA hybridization analysis showed the presence of the structural gene of the kanamycin resistant determinant in total DNA isolated from several independent transformants. All data presented clearly demonstrate the transfer, stable maintenance and functional expression of the kanamycin resistance marker in Medicago varia cells which retain their morphogenic property.