ONION IS A MONOCOTYLEDONOUS HOST FOR AGROBACTERIUM

Onion (Allium cepa cvs Pukekohe Longkeeper and Early Longkeeper) bulbs and leaves were inoculated with 25 virulent strains of Agrobacterium. Eleven strains of Agrobacterium tumefaciens, one of A. rubi and six of A. rhizogenes induced tumorous growths. One A. rhizogenes strain, HRI produced a root-like structure arising from a tumour at the base of onion bulbs. The majority of these tumours produced nopaline, suggesting that transformation has occurred. In contrast, neither nopaline nor octopine was ever detected in extracts of tumour-free inoculation sites which had been inoculated with virulent or avirulent strains. Tumours appeared earlier on bulbs inoculated with Agrobacterium cultured in the presence of acetosyringone. © 1990.