Construction of bacterial consortium to promote maize growth: study of interaction, growth promotion and modulation of gene expression

Abstract

Plant growth promoting bacteria (PGPB) act directly and indirectly by facilitating nutrient acquisition, plant hormone production, mitigation of (a)biotic stresses and induction of systemic resistance. Regarding the increasing demand for agricultural products worldwide, PGPB offer more sustainable biotechnological solutions to partially or completely replace application of chemical supplies in agriculture. Our hypothesis is that the effects of growth promotion can be enhanced with the use of BPCPs in consortia, since different bacterial species can act synergistically, among them a complementation of the ability to promote plant growth by different mechanisms. Thus, the present work aims to build a bacterial consortium that promotes maize growth composed of PGPB strains with compatible and complementary metabolic and ecological functions. To elaborate the consortium, bacterial strains will be isolated from soil and corn rhizosphere and then the PGPB will be selected based on taxonomic identification and physiological characterization in vitro (biological nitrogen fixation, phosphate solubilization, siderophore production, indole-3-acetic acid (IAA) production, aminocyclopropane-1-carboxylic acid (ACC) deaminase synthesis, exopolysaccharides production and biofilm formation) of strains isolated from soil and maize rhizosphere-associated community. To elucidate the behavior of PGPB during interaction with maize, the strains will be target with fluorescence genes. Bacterial consortium and isolated strains will be evaluated in a greenhouse assay by collecting images with high-throughput phenotyping platforms and sampling of plant tissue for gene expression analyses by RT-qPCR and fluorescence microscopy. We expect the plant growth-promoting effects with the use of PGPBs will be enhanced with the formation of the bacterial consortium. The integration of high-throughput phenotyping, gene expression and fluorescence microscopy data will be crucial for the elucidation of the PGPB-plant interaction.