Pseudomonas chlororaphis (Pc) representatives are found as part of the
rhizosphere-associated microbiome, and different rhizospheric Pc strains
frequently perform beneficial activities for the plant. In this study we
described the interactions between the rhizospheric Pc strains PCL1601,
PCL1606 and PCL1607 with a focus on their effects on root performance.
Differences among the three rhizospheric Pc strains selected were first
observed in phylogenetic studies and confirmed by genome analysis, which
showed variation in the presence of genes related to antifungal compounds or
siderophore production, among others. Observation of the interactions among
these strains under lab conditions revealed that PCL1606 has a better
adaptation to environments rich in nutrients, and forms biofilms. Interaction
experiments on plant roots confirmed the role of the different phenotypes in
their lifestyle. The PCL1606 strain was the best adapted to the habitat of
avocado roots, and PCL1607 was the least, and disappeared from the plant
root scenario after a few days of interaction. These results confirm that 2 out 3
rhizospheric Pc strains were fully compatible (PCL1601 and PCL1606),
efficiently colonizing avocado roots and showing biocontrol activity against
the fungal pathogen Rosellinia necatrix. The third strain (PCL1607) has
colonizing abilities when it is alone on the root but displayed difficulties
under the competition scenario, and did not cause deleterious effects on the
other Pc competitors when they were present. These results suggest that
strains PCL1601 and PCL1606 are very well adapted to the avocado root
environment and could constitute a basis for constructing a more complex
beneficial microbial synthetic community associated with avocado plant roots.
