Increased phosphate solubilization by rhizospheric sugarcane interspecies interactions

Abstract

Plant-associated microbiota can enormously influence on plant traits. Manipulation of these microbial communities holds great potential as an effective way to improve crops, while contributing to a more environmentally benign agriculture. Revealing the chemical communication network in the rhizosphere will pave the way for the future production of bioinoculants using bacterial consortia. In this work, we isolated numerous microorganisms from the sugarcane rhizosphere, sequenced the 16S rDNA of a subset of isolates showing different cultural features and evaluated their ability to solubilize phosphate in NBRIP medium. Next, using only phylogenetically different isolates growing in solid medium containing salts, amino acids and sucrose, we tested interspecies interactions in pairwise combinations. Interactions were followed for 7 days and cultural traits such as growth inhibition, growth promotion, colony morphology changes and pigment production were registered. We focused in one peculiar interaction that involved isolate 258 promoting growth of isolate 214 while the latter inhibited growth of 258. In addition, 258 enhanced the ability of 214 to solubilize phosphate. To analyze if this phenomenon was due to a secreted metabolite, supernatants were tested. Interestingly, we observed that cell-free supernatants of isolate 258 were able to induce 214 phosphate solubilization. We are currently performing experiments to elucidate the chemical nature of the metabolites responsible for this phenotype.