Beneficial microbe application on tomato plants significantly improves the accumulation of metabolites with nutraceutical value

The use of microorganisms and biostimulants is increasingly supported in agriculture due to their advantageous impact on plant disease management, growth enhance- ment, and the synthesis of beneficial bioactive second- ary metabolites (SMs). Tomato (Solanum lycopersicum) is an important crop consumed worldwide since it is an excellent source of natural compounds (i.e., b-carotene and flavonoids) and minerals useful for human health. In this study, the improvement of the nutritional value of tomato (S. lycopersicum var. Heinz), by using beneficial microorganisms, including selected strains of Streptomy- ces microfiavus (S), Trichoderma harzianum (M10) and T. afroharzianum (T22), has been investigated. These microbes were applied to tomato plants as single inocu- lants or microbial consortia. The effects were evaluated through statistical analysis of biological parameters. T22 treatments significantly increased plant height compared to control and M10-based treatments. The similarities observed in plant height between S-treated plants and those treated with the combination of S and T22 highlight the potential beneficial effects of micro- bial consortia. Moreover, the berries were subjected to an untargeted metabolomic analysis by LC-MS qTOF that led to the identification of 18 metabolites, including tomatine and its derivatives solafloridine. Multivariate analysis demonstrated differences in berries metabolic profiles, depending on the treatment. Specifically, T22- based treatment increased the accumulation of most of the identified metabolites compared to untreated plants, while combined treatment S+T22 induced a significant accumulation of solafloridine. In conclusion, field micro- bial applications significantly induced metabolic profile change in tomatoes and the accumulation of metabolites with nutraceutical value.