Acquisition of virulence by non-pathogenic isolates of Agrobacterium radiobacter

Abstract

Tumours developed on tomato plants inoculated with Agrobacterium radiobacter var. tumefaciens biotype 2. When tumours were contaminated with the saprophyte, Agrobacterium radiobacter var. radiobacter biotype 1, the previously saprophytic bacterium became virulent. Acquisition of virulence was dependent on the efficiency of the recipients, on the duration of contact between saprophyte and tumour and on the stage of tumour development. A difference in the efficiency of the donors was not detected. There was no evidence for acquisition of virulence when the bacteria were mixed in liquid culture.