Pathogenicity of Pseudomonas syringae subsp. savastanoi muntants defective in phytohormone production
1994
Iacobellis, N.S. (Universita della Basilicata, Potenza (Italy). Dip. die Biologia. Difesa e Biotecnologie Agrarie-Forestali) | Sisto, A. | Surico, G. | Evidente, A. | DiMaio, E.
The present study compares the pathogenicity on olive and oleander plants of three wild-type strains of Pseudomonas syringae subsp. savastanoi (ITM317 and PBa230 from olive and ITM519 from oleander) and three phytohormone-deficient mutants of ITM519:TTM519-41 (Iaa(+)/cytokinins(-)), ITM519-7 (Iaa(-)/cytokinins(+)), ITM519-6 (Iaa(-)/cytokinins(-)). Mutants not producing IAA (ITM519-7 and ITM519-6) only induced necrosis of the inoculated tissues (ITM519-6) or swellings on the stems attributed to cytokinin production accompanied by necrosis (ITM519-7). By contrast, the Iaa(+)/cytokinins(-) mutant (ITM519-41) induced attenuated symptoms on stems and knots similar to those obtained with the parent strain on oleander leaves. Olive strains induced necrosis of oleander leaves and were virulent and avirulent, respectively, on olive and oleander stems. Strain ITM519 and its three mutants were all able to multiply in oleander leaves at similar rates, reaching the same final populations. By contrast, the two olive strains multiply poorly, reaching populations c. 10(2)-fold lower
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