From the root to the stem: interaction between the biocontrol root endophyte Pseudomonas fluorescens PICF7 and the pathogen Pseudomonas savastanoi NCPPB 3335 in olive knots.
Bottom Line: While PICF7 was not able to suppress disease development, its presence transiently decreased pathogen population size, produced less necrotic tumours, and sharply altered the localization of the pathogen in the hyperplasic tissue, which may pose epidemiological consequences.However, presence of the BCA seemed to confine P. savastanoi at inner regions of the tumours.This approach has also enabled to prove that the pathogen can moved systemically beyond the hypertrophied tissue.
Affiliation: Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas-CSIC, Alameda del Obispo s/n, Apartado 4084, E-14080 Córdoba, Spain.Show MeSH
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Mentions: Results showed that when P. fluorescens PICF7 was inoculated into the stems along with the pathogen, population size of NCPPB 3335 sharply decreased and was significantly (P < 0.05) lower during the first 2 weeks after bacterization, compare with that scored in plants only inoculated with Psv (control treatment). However, this fall in the pathogen population was only transitory and Psv counts recovered later on and did not differ significantly (P > 0.05) between treatments until the end of the bioassays (64 DAI) (Fig. 1). Population sizes of PICF7 did not significantly differ (P > 0.05) regardless the presence (3.3 ± 0.2 at 0 DAI and 6.4 ± 0.4 at 60 DAI around the inoculation points and developed tumours respectively) or absence (segments containing the inoculation point, see above) of the pathogen. Interestingly enough, co-inoculation of PICF7 with Psv significantly altered the macroscopic appearance of the tumours. Thus, less necrotic knots (discoloured, whitish tumours) developed when PICF7 was co-inoculated with the pathogen (Fig. 2A and C) in comparison with knots developed in plants inoculated with Psv alone (Fig. 2B and D).
Affiliation: Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas-CSIC, Alameda del Obispo s/n, Apartado 4084, E-14080 Córdoba, Spain.