Format: ORAL

Giulia Ghirardello1,2, Nicole Zerbetto1,2, Rosalba Cipriani1,2, Sebastiano Nigris1,2, Barbara Baldan1,2

1 University of Padua, Padua, Italy 2 Botanical Garden of Padua, Padua, Italy

Plants cohabit and interact with diverse soil microorganisms, that are archaea, bacteria, fungi, and protists, which form the root microbiota. These communities play a pivotal role in enhancing plant growth through improved nutrient uptake, immunity, and stress tolerance. Here, we examine the role of bacterial species of a commercial compost on Solanum lycopersicum (tomato) growth and health. Firstly, we identified six main bacterial species from the culturable microbiota of the compost, belonging to Bacillus, Kocuria, Glutamicibacter and Microbacterium genera. Tests for their plant growth-promoting traits revealed their capacity to solubilize phosphorus, produce siderophores and synthesise auxin. To investigate the plant responses to the colonization, the tomato seedlings were grown in soil enriched with the inoculum of the single bacterial species. RTqPCR highlighted a specificity in the expression profile of genes representing pathways involved in plant-microbe interplays, such as flavonoid biosynthesis and ethylene production, in response to the different bacterial strains. RNAseq analysis of the host transcriptome will provide a wider overview of the plant response to the rhizobacteria, hence pointing out other pathways influenced by the interaction. Moreover, some of the isolated bacterial strains were transformed to express fluorescent-tag proteins. This will enable the tracking of rhizobacteria accommodation on the tomato root and the description of their spatial distribution from different plant root surfaces to inner tissues by confocal microscopy. This study aims to contribute to the decipherment of the molecular signalling behind the interactions between plants and bacteria in the context of the promotion of sustainable agriculture practices proposed by the European Union within the EU Sustainable Goals 2030.