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: An interesting finding from CLSM experiments was the repeated observation of Psv-GFP colonies in stem tissues outside the hyperplasic region. Thus, CLSM imagery revealed that the pathogen could move from the inoculation point to healthy areas of the stem, colonizing the xylem vessels (Fig. 6). Psv-GFP cells were first observed 2 weeks after inoculation in xylem vessels close to the tumour (data not shown). At later times after inoculation (4 weeks) Psv-GFP cells were visualized either within the xylem vessels nearby the tumour (node) (Fig. 6B and E) or beyond the hyperplasic tissue (internode) (Fig. 6A and D). Finally, presence of strain PICF7 did not interfere with Psv movement outside the hyperplasic region and throughout the vascular system since the pathogen was also found in stems of Psv/PICF7 co-inoculated plants 2 weeks after inoculation (Fig. 6C and F).
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.