The volatile profiles of three strawberry varieties exhibit common and distinct responses to the inoculation with Rhizophagus irregularis and different Pseudomonas fluorescens strains

Cultivated strawberry dominates fruit production of the northern hemisphere and provide essential nutrients for human health. However, strawberry production has still a negative impact on agricultural soil and fruit quality does not always meet consumer expectations. Plant-microorganism interactions engineering involving arbuscular mycorrhizal fungi and rhizobacteria is known to alter plant’s metabolic pathways and shape fruit quality (flavour and nutrient content). In our study, 21 Pseudomonas fluorescens strains were isolated from a two-year strawberry cultivation system and screened for their plant growth promoting activities. Four P. fluorescens were selected based on their activity and phylogenetic groups and inoculated in association or not with Rhizophagus irregularis DAOM 197198 on 3 different strawberry genotypes. The volatile profiles of the harvested strawberries were analysed by GC-MS. The abundance of hexanal, a compound used to extend shelf-life and reduce post-harvest diseases, was found more abundant in strawberry fruit from plants inoculated with the AMF R. irregularis than in non-Ri plants. The study showed that metabolite content of strawberries is significantly different between cultivars but exhibits a distinct and consistent pattern in response to P. fluorescens in association or not with the AMF R. irregularis. Our results suggest that the inoculation with P. fluorescens and R. irregularis improves strawberry quality and fine-tunes taste to consumer preference. Broadly, microbiome engineering has the potential to tailor fruit flavour to consumer taste while increasing nutritional benefits and food safety.