Microbial consortium can enhance plant growth, control leaf miners and 1 parasitic root nematodes in tomato crops grown in Mediterranean greenhouse

Giulio Flavio Rizzo¹Luca Ciccarello²Donata Arena^2,3*Vittoria Catara²Gaetano Siscaro²Valentin Gfeller^4*Monika Maia Messmer⁴Ferdinando Branca²

• ¹Universita degli Studi di Bologna, Bologna, Italy
• ²Universita degli Studi di Catania Dipartimento di Agricoltura Alimentazione e Ambiente, Catania, Italy
• ³University of Catania, Catania, Italy
• ⁴Forschungsinstitut fur Biologischen Landbau, Frick, Switzerland

Microbial inoculants based on plant growth-promoting microbes offer a promising alternative to chemical 10 inputs, enhancing plant growth, crop yield, and stress resilience without adverse environmental effects. A 11 commercial microbial consortium (Bacillus spp., Pseudomonas spp., Streptomyces spp., Trichoderma spp., Glomus 12 spp.) was evaluated in a cold greenhouse in Sicily (Italy), certified for organic methods. The consortium was 13 applied by fertigation to five tomato cultivars, including one commercial and four Sicilian landraces. The 14 greenhouse was naturally infested with the tomato leaf miner Phthorimaea absoluta, which affected plant growth 15 and yield. Despite the considerable infestation, plants treated by the above-cited microbial consortium showed 16 enhanced growth and yield compared to the control plants. Furthermore, root galls caused by nematodes 17 (Meloidogyne spp.) were observed. Significant differences were observed among the genotype and the treatment. 18 Microbial DNA was extracted from tomato roots and analysed using amplicon sequencing to characterize the 19 root-associated bacterial, fungal, and nematode communities. Alpha diversity indices were largely unaffected 20 for bacteria. In contrast, the genotype and the soil treatment by the microbial consortium affected the alpha 21 diversity indices for fungi and nematodes. Beta diversity analysis revealed significant differences in microbiota 22 community composition between plants grown in treated and untreated soils for both datasets analysed. 23 Furthermore, we found several Operational taxonomic units associated with the soil treatment by the microbial 24 consortium utilized. Finally, the results demonstrated that the microbial consortium utilized alleviated the 25 damage symptoms due to biotic stresses (P. absoluta and Meloidogyne spp.). Furthermore, the treatment 26 significantly affected the microbial community of the tomato roots depending on the cultivars used.