Impact of Amino Acid Supplementation on Rhizosphere Bacterial Dynamics in Rice Under Phosphorus Deficiency

Plant roots release a diverse array of metabolites into the rhizosphere, including amino acids. However, the impact of amino acids under phosphorus deficiency on rhizosphere bacterial communities in rice remains poorly understood. As such, this study aimed to determine the effects of amino acid enrichment on rhizosphere bacterial communities in rice under phosphorus-deficient conditions. Rice (Oryza sativa cv. Haenuki) was grown in an Andosol with four amino acid-addition treatments: cysteine, tyrosine, glycine, or glutamine, as well as a control where no amino acid was added (low P). Shoots and roots were collected at 17 and 23 days after sowing (DAS), and rhizosphere bacterial communities were analyzed through 16S rRNA gene sequencing. Amino acid addition altered the composition of bacterial communities, with Proteobacteria having the highest relative abundance across all treatments (29.0–36.6% at 17 DAS, 32.6–39.4% at 23 DAS). Across genera, Flavisolibacter dominated in all amino acid treatments at 17 DAS (6.2–9.6%) and remained prevalent at 23 DAS, except in the glutamine treatment, where Kaistobacter was most abundant (5.3%). A total of 93 bacterial genera at 17 DAS and 106 at 23 DAS were identified as phosphate-solubilizing bacteria. We demonstrate that amino acid additions to rice grown under low phosphorus conditions changed the rhizosphere bacterial communities. Notably, only specific bacterial genera showed positive correlations with shoot and root dry weight, as well as with shoot phosphorus concentration and uptake. © The Author(s) under exclusive licence to Sociedad Chilena de la Ciencia del Suelo 2025.