Isolation ofAgrobacteriumsp., strain from theAzollaleaf cavity

We have isolated a bacterial strain from surface sterilized fronds of the aquatic fern Azolla filiculoides and infer that it occurs in leaf cavities, along with the nitrogen-fixing cyanobacterium Anabaena azollae. This strain grew slowly on rich media, appeared to be Gram-negative, and was identified using a bacteriological multitest system as Agrobacterium sp. This strain, designated AFSR-1, could grow in the presence of 400 ppm of ammonium sulphate. DNA/DNA hydrodization analysis showed that a 16 S ribosomal RNA gene is located in the AFSR-1 strain on an identical DNA restriction fragment as in a strain of Agrobacterium tumefaciens. In addition, it was found that strain AFSR-1 contained DNA regions homologous to the modulation genes nodABC and nodL of Rhizobium trifolii, AFSR-1 contains a cryptic plasmid, and the genetic transfer of a broad-host-range plasmid pLAFR3 to strain AFSR-1 was achieved.