GENETIC-TRANSFORMATION IN SAPROPHYTIC NIT ROGEN-FIXING AGROBACTERIUM-RADIOBACTER 5D-1

The efficiency of transformation of saprophytic nitrogen-fixing strain 5D-1 of Agrobacterium radiobacter with plasmid (pVZ361) and chromosom al DNA (markers trp(+), his(+), and Km(r)) was 10(4) and 10(2) per mu g DNA, respectively. The use of electroporation provided a five-fold i ncrease in the efficiency of transformation with plasmid DNA and a 20- to 100-fold increase with the chromosomal genes (up to 5.0 x 10(4) an d 9.5 x 10(3) per 1 mu g DNA, respectively). Both small and large plas mids with heterologous genes cloned in them could be introduced into r ecipient A. radiobacter 5D-1 cells by using electroporation. Transform ation of chromosomal genes by electroporation proved that transposon T n5 induced mutations Cal(-), Nm, and Nr, which alter the processes of interaction with plants and nitrogen metabolism, are linked to the tra nsposon marker Km(r).