Pseudomonas protegens CHA0 does not increase phosphorus uptake from 33P labeled synthetic hydroxyapatite by wheat grown on calcareous soil

Abstract

Please cite this article as: Meyer, G., Maurhofer, M., Frossard, E., Gamper, H.A., Mäder, P., Mészáros, É., Schönholzer-Mauclaire, L., Symanczik, S., Oberson, A., Pseudomonas protegens CHA0 does not increase phosphorus uptake from 33 P labeled synthetic hydroxyapatite by wheat grown on calcareous soil, Soil Biology and Biochemistry (2019), doi: https://doi. Abstract 18Soil microorganisms exuding organic acids have the potential to solubilize inorganic 19 phosphorus (P), which could improve the P availability to plants growing on calcareous 20 soil. The gluconic acid exuding bacteria Pseudomonas protegens CHA0 can solubilize 21 P under glucose rich in vitro conditions, but evidence on the effectiveness in soil is 22 from the two bacterial inoculants suggested that overall microbial activity, i.e., via 36 protonation due to respiration, increased inorganic P mobilization. P solubilizing 37 bacteria should be evaluated using a tracer and an appropriate bacterial control in 38 order to reveal the mechanisms involved in increased plant available P in soil 39 inoculated with P solubilizing bacteria. 40

Roles of Phosphate Solubilizing Microorganisms from Managing Soil Phosphorus Deficiency to Mediating Biogeochemical P Cycle

“…The PSM-mediated bioavailable P is not utilized directly by plant or soil microbes; instead, it is quickly subject to precipitation or adsorption reactions in the immediate vicinity in which it is solubilized or desorbed by PSM [140]. Additionally, the P solubilization of exogenous PSM may be reduced due to the lack of persistence by competition with endogenous microbes for P resources, or by maladjustment of newly inoculated soil environment [141,142]. Hence, the PSM-enhanced P uptake from soil to plant likely occurs in the rhizosphere environment, which provides higher growth potential for PSM than bulk soils [74,142].…”

Phosphate‐solubilising microorganisms for improved crop productivity: a critical assessment

“…New Phytologist (2021) 229: 1268-1277 Ó 2020 The Authors New Phytologist Ó 2020 New Phytologist Trust www.newphytologist.com However, few studies have shown that this mechanism is effective under field conditions (Karamanos et al, 2010;Leggett et al, 2015). Furthermore, microorganisms are unlikely to use energy to solubilise P if they do not need it themselves, especially in a soil environment under intense competition with other microorganisms (Meyer et al, 2019). Phosphate solubilisation by PSM in order to serve the plant is therefore questionable.…”

“…However, their capacity to occupy specific ecological niches within the soil matrix, such as the rhizosphere, and subsequently function within these niches, remains important (Wakelin et al ., 2007). A lack of PSM performance on crop productivity and P uptake is often presumed to be related to poor soil colonisation due largely to competition with other microorganisms (Richardson, 2001; Meyer et al ., 2019; Raymond et al ., 2019a). Suppression of competition with native microbial communities, for example using sterilised soils, resulted in higher abundance and more positive effects of PSM on plant growth and P nutrition (Vassilev et al ., 2006; Pande et al ., 2017; Efthymiou et al ., 2018; Sarabia et al ., 2018).…”

“…The limited effect of OA on P solubilisation in soil in relation to C supply limitation was recently illustrated by Meyer et al . (2019). Solubilisation of a 33 P‐labelled synthetic hydroxyapatite by a well described Pseudomonas PSM was investigated in a sterilised soil complemented with glucose, in which no demonstrable P solubilisation by the PSM occurred.…”

“…Furthermore, most studies found in the literature have reported ‘positive effects’ of PSM on plant growth under controlled conditions, whereas field experiments more frequently have failed to demonstrate a positive response. Studies showing positive and no effects on crop responses have rarely evaluated the conditions that allow an effect to occur or investigated why outcomes are inconsistent (Fanelli, 2012; Meyer et al ., 2017; Gómez‐Muñoz et al ., 2018; Meyer et al ., 2019).…”