S14 - Session O1 - Exploring the potential of fruit-isolated microbes as biological control agents against Botrytis cinerea in strawberry

Authors: Chiara Murena, Antonia Barberio, Héber Oliveira, Tania R. Fernandes *, Susana M. P. Carvalho

Botrytis cinerea is a devastating fungal pathogen that causes grey mould (GM) disease, being the main reason for fruit rejection and economic losses throughout the strawberry ( Fragaria × ananassa ) supply chain. So far, tolerant strawberry genotypes have not been identified. Consequently, control of GM mostly relies on excessive application of chemical fungicides, yet they are generally ineffective due to increasingly fungal resistance. Biological control has emerged as a promising and sustainable alternative to phytopharmaceutical products, reducing product chemical residues. Although endophytic microbes (fungi and bacteria) from strawberry fruits might play a role in preventing GM disease, their effect has been poorly explored so far. Thus, the aim of this study was to: i) test the susceptibility of three economically relevant strawberry cultivars (San Andreas, Portola and Albion); and ii) explore the antagonistic ability of microbes isolated from unripe and ripe fruits against B. cinerea . Our results have demonstrated that the three studied cultivars did not differ in their susceptibility to B. cinerea . Further, CFUs determination have revealed that unripe fruits presented higher diversity and abundance of microbes than ripe fruits. Five microbes exhibiting different phenotypes were isolated and tested against B. cinerea. Interestingly, a yeast-like fungus showed to significantly reduce B. cinerea colony area in a dual culture assay. Furthermore, a culture filtrate of this agent strongly prevented B. cinerea conidia germination suggesting that released metabolite(s) might have a critical role on GM mitigation and these are being currently analyzed. Understanding the effect of this isolated microbe on host defense responses and on fruit quality parameters may be critical to integrate this biocontrol agent for GM disease management in strawberry.