Rice (Oryzae sativa L.) is the staple food supplying more than half of the world’s population. However, phosphorus deficiency is a major factor limiting rice yield, since P is often not readily available due to tight binding in Fe-P or Al-P forms. As the key driver of the element biogeochemical cycle, soil microorganisms play an important role in the promotion of soil P availability.

Researchers from the Institute of Urban Environment, Chinese Academy of Sciences, investigated the effect of soil P availability（0，50，200 mg P₂O₅ kg^-1）on the soil phosphate-solubilising microbial community in the rice rhizosphere under a P-deficient paddy soil via stable isotope probing of phospholipid fatty acids and DNA and high-throughput sequencing methods.

Compared with controls (23.4–62.2‰), the δ¹³C values of 16:1ω7c, 18:1ω7c, and 18:1ω9c (Gram-negative bacteria) increased to 69.2–167.4‰ with low P input, but decreased to 6.6–58.6‰ under high P input. Similarly, higher ¹³C enrichment (1.04–1.47 ng g^-1 dry weight soil) was observed in phospholipid fatty acids (16:1ω7c, 18:1ω7c and 18:1ω9c) with low P input. High-throughput sequencing indicated that low rather than high P input promoted the growth of P-solubilising Bacillus, Alicyclobacillus, and Clostridium. The relative abundance of these organisms increased significantly in light DNA fractions following both ¹²C and ¹³C treatments, suggesting they seldom use rice root derived carbon as carbon sources. By contrast, P-solubilising Rhizobiales, Rhodospirillales, and Myxococcales preferred root-derived carbon under P input conditions. Community and phylogenetic analysis of genes related to P solubilisation (alkaline phosphatase phoD and pyrroloquinoline quinone pqqC) indicated a dominant role for Rhizobiales and Actinomycetales in paddy soil P solubilisation.

This study was published in Soil Biology and Biochemistry entitled "Phosphate levels influence the utilisation of rice rhizodeposition carbon and the phosphate-solubilising microbial community in a paddy soil". This work was supported by the National Natural Science Foundation of China, and the Strategic Priority Research Program of Chinese Academy of Sciences.