Association of the mycorrhiza-like fungus Serendipita indica with bacteria to enhance plant resistance against fungal pathogens

Serendipita indica (syn. Piriformospora indica) is a root-colonizing endophytic fungus that boosts plant vigor and confers resistance against plant pathogens. This fungus is further known as having a bacterial endosymbiont living inside its hyphae. Similarly, some bacterial endophytes promote plant growth and enhance plant resistance. The application of this fungus as a biostimulant often leads to irregular performance in the field, perhaps due to antagonisms with other microbes. We aimed at boosting effects of the fungus and its bacterial symbiont on plants by combining the fungus and its symbiont with selected bacterial helpers.

A collection of bacteria from roots of potato and tomato plants were isolated and combined with the beneficial fungus Serendipita indica in order to study the type of interaction. Some bacterial endophytes stimulate Serendipita growth and colonize its hyphae. Some combinations of the beneficial fungus with endophytic bacteria can further help to reduce tomato wilt disease caused by Fusarium oxysporum, while others do not. Genomes of selected isolates have been sequenced and annotated to understand how the bacteria interact positively with the fungus.

The future transcriptomics analyses of tomato plants inoculated with only Serendipita or combinations of the fungus and bacteria will unravel the mechanisms behind these interactions, identifying genes up- and down-regulated during the interplay. The mechanisms of the bacterial helpers on the fungus and its symbiont will be further elucidated to understand better the multi-partite interactions between a fungus, bacterial symbiont, the helpers, and the plant.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 676480.