Banana is one of the most important cash crop in the world, seriously threatened by Fusarium oxysporum f. sp. cubense (Foc) race 4. The implementation of integrated disease management strategies for the effective control of this pathogen is recommended. A promising measure within this holistic framework is the use of microorganisms showing biocontrol. Pseudomonas simiae PICF7 stands out as a well-known, highly-versatile beneficial root endophytic bacterium displaying biocontrol and plant-growth promotion abilities under diverse experimental conditions. Effectiveness of any given biological control agent (BCA) primarily relies on the successful colonization of the ecological niche or microhabitat where its beneficial effect is expected. Moreover, formulation and release of BCAs require risk assessment analyses in order to ensure low or null impacts on non-target organisms as well as to the environment.

We have proved that strain PICF7 is an effective biological control agent (BCA) against Fusarium oxysporum f. sp. cubense tropical and subtropical race 4 (STR4 and TR4), causal agent of Fusarium Wilt of Banana. This BCA performed even better than indigenous rhizobacteria isolated from banana roots (cv. Cavendish) in Canary Islands. Besides, strain PICF7 is able to colonize banana roots endophytically and to promote banana growth under controlled conditions. Introduction of PICF7 on the banana holobiont did significantly alter neither the composition nor the structure of the indigenous banana root microbiota, since no permanent effect on the community composition was observed. Nevertheless, this BCA is able to enter in the banana root microbial co-occurrence network. It also produces shifts in the interactions among components of the banana root microbiota. The low impact on the resident microbiota confers an ecological advantage regarding future field applications of this BCA. This effect, together with the induction of defence-related genes, makes PICF7 a promising candidate to develop bioformulations based on this endophyte.