Potential role of rhizosphere microbiome on root exudations and phosphorus uptake of rice under flooded soil culture

Abstract

Purpose The response of rice plants to P deficiency together with rhizosphere microorganisms is yet to be explored in flooded soil cultures. This study aimed to identify how alterations in bacterial diversity are associated with underground metabolic and chemical reactions in the rhizosphere of rice. Methods Two rice varieties were grown in a split-root box under flooded conditions and filled with either P-applied or non-P-applied soils with or without γ-irradiation. At 41–42 days after transplanting, plant biomass, P uptake, exudation rates of total carbon and low-molecular-weight organic acids (LMWOAs) from the roots, and bacterial diversity, P fractions, and phosphatase activity in the rhizosphere were determined. Results γ-irradiation significantly decreased plant P uptake and biomass of both varieties and reduced the relative abundance of Alphaproteobacteria and microbiome beta diversity in the rhizosphere. Concurrently, the use of insoluble P in soils was evidently reduced by irradiation. These microbiological and chemical changes in the γ-irradiated rhizosphere occurred in both P-applied and non-P-applied soils. On the other hand, the proportion of LMWOAs and exudation of citric acid, high in P-solubilization capacity were increased in the γ-irradiated and P-applied rhizosphere soils at the expense of other carbons. No differences were detected in phosphatase activity in any treatments. Conclusion Dysbiosis in the rhizosphere microbiome negatively affected rice growth and the use of insoluble P pools in flooded soil cultures. With a reduction in microbiome diversity, rice plants may have a complementary strategy to increase the exudation proportion of citric acid toward the P-rich soil area.

The Underground World of Plant Disease: How Does Rhizosphere Dysbiosis Affect Plant Health Above-ground?

“…The majority of genes significantly altered still have no specific function designation, followed by genes related to the physical structure of the cell and transport mechanisms, which were both up-and down-regulated. These results suggest that the plants, after infection, were remodeling their cellular components and alterations in nutrient or molecular transport in response to the treatment (Bai et al 2022, Mukai et al 2022.…”