Organic anions facilitate the mobilization of soil organic phosphorus and its subsequent lability to phosphatases

Abstract

Organic anions commonly released from plant roots are widely reported to mobilize soil phosphorus (P). We characterized soil organic P that was mobilized by organic anions and assessed its amenability to hydrolysis by phosphatase enzymes. MethodsSix soils differing in organic P content were extracted with citrate, malate or oxalate solutions and incubated with preparations of phosphomonoesterase, phosphodiesterase, or phytase. Organic P compounds present in these extracts were putatively identi ed and quanti ed with solution 31 P NMR spectroscopy and the enzyme-labile P fractions were assessed by changes in molybdate reactive P (MRP) concentration. ResultsOrganic P mobilization varied markedly among the organic anions. Extraction with 10 mM citrate was most effective and extracted 7.8-fold more total P than the water controls across all soils. Approximately 95% of the extracted P was non-MRP. The organic anions increased both the amount of P extracted and the proportion of the total extracted P that was phosphatase labile. Phytase was generally the most effective enzyme with up to 60% of the total non-MRP being amenable to hydrolysis by phytase across all extracts. The presence of inositol hexakisphosphates in the extracts, as well as other forms of organic P including nucleic acids and phospholipids, was veri ed by 31 P NMR with concentrations dependent on both organic anion and soil type. ConclusionThe combination of organic anions and phosphatases represents a key mechanism by which plants and microorganisms can enhance the bioavailability of soil P. This has important implications for understanding P dynamics in natural and managed ecosystems and for ongoing efforts to improve the P-use e ciency of agricultural plants.

Chemical processes in receiving soils accelerate solubilisation of phosphorus from desert dust and fire ash

“…For the dust samples, three concentrations were tested (5, 10 and 20 mM), and for the crop ash sample four concentrations were tested (5, 10, 20 and 50 mM). This range of concentrations falls within the typical range of OA and MA reported in the rhizosphere of various plants in different soil types (Jones, 1998; Richardson et al, 2022; Strobel, 2001; Wang et al, 2015) and on the surface of plant leaves (Yoshida et al, 1997). To test the additive role of OA and MA on P solubilisation of dust and ash we have used an additional solution containing a mixture of 10 mM of OA and MA (1:1 ratio, total 20 mM).…”

The potential of biostimulants on soil microbial community: a review

“…These enzymes, composed of phosphomonoesterases and phosphodiesterases, are included in the production of orthophosphate from organic P (Richardson et al, 2022). Organic phosphates do occur as a single-ester or double-ester bond that is joined by unique organic catalysts, phosphomonoesterases or phosphodiesterases.…”

Scientific impact, direction and highlights of Plant and Soil in the 30 years since Professor Hans Lambers became Editor in Chief

“…In addition to the papers cited above, Hans Lambers suggested four more papers (Brown et al 2017;Li et al 2009;Marschner and Römheld 1994;Richardson et al 2022) that were likely to be among the most impactful papers published in Plant and Soil during his tenure as Editor in Chief. The review by Marschner and Römheld (1994) is a classic textbook reference and was credited with 421 citations in the WoS Core Collection on 1 st May 2022.…”