Pathogenicity of strains of Pseudomonas syringae pv. savastanoi and their indoleacetic acid-deficient mutants on olive and oleander.
In further studies [RPP 61, 6883] the pathogenicity on olive and oleander plants of wild-type and indoleacetic acid (IAA)-deficient (Iaa-) mutant strs. of the pathogen from olive, oleander and privet was compared. All wild-type isolates from oleander were tumorigenic on oleander. Only wild-type isolates from oleander were tumorigenic on oleander except for olive isolate EW1017 which also caused galls on oleander; however, this str. resembled strs. from oleander in that IAA genes were plasmidborne. Iaa- mutants of the strs. from olive and privet did not induce galls on olive and oleander. Iaa- mutants of strs. from oleander produced no symptoms on oleander plants, but induced atypical galls on olive plants. The role of bacterial production of IAA in gall formation on the olive and oleander knot diseases was thus confirmed.