Colonization process of olive tissues by Verticillium dahliae and its in planta interaction with the biocontrol root endophyte Pseudomonas fluorescens PICF7.
Bottom Line: Isolate VDAT-36I quickly colonized olive root surface, successfully invaded root cortex and vascular tissues via macro- and micro-breakages, and progressed to the aerial parts of the plant through xylem vessel cells.For the first time using this approach, the entire colonization process of a woody plant by V. dahliae is reported.Early and localized root surface and root endophytic colonization by P. fluorescens PICF7 is needed to impair full progress of verticillium wilt epidemics in olive.
Affiliation: Departamento de Mejora Genética, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas, Alameda del Obispo s/n, Apartado 4084, 14080 Córdoba, Spain.Show MeSH
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Mentions: A decrease (in same cases a complete absence) of detectable VDAT‐36I biomass within root regions where P. fluorescens PICF7 had already endophytically established was consistently monitored from 10 DAI onward. Figure 4 shows a comparison between a transverse cross‐section of a non‐bacterized ‘Arbequina’ plant, where yellow dots denoted inter‐ and intra‐cellular presence of VDAT‐36I hyphae in the root cortex and vascular tissue (Fig. 4A). In contrast, PICF7‐treated plants sampled at the same time (10 DAI) showed the presence of bacteria microcolonies among the intercellular spaces of the root cortex, proximal to the vascular tissue, without detectable trace of any VDAT‐36I biomass (Fig. 4B). From this stage until 60 DAI, no significant change with regards to PICF7 colonization was observed. Finally, VDAT‐36I could be detected within the secondary xylem vessel cells of stems and petioles of plants where pathogen colonization was not fully impaired by PICF7 (data not shown).
Affiliation: Departamento de Mejora Genética, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas, Alameda del Obispo s/n, Apartado 4084, 14080 Córdoba, Spain.