Engineering phosphate solubilization microorganisms and deciphering the mechanism of phosphate solubilization during plant-microbe interactions

Project Information

ePSM

Grant agreement ID: 101063930

DOI

10.3030/101063930

Project closed

EC signature date 21 June 2022

Start date 1 April 2023

End date 31 March 2025

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 189 687,36

Coordinated by

MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV
Germany

Periodic Reporting for period 1 - ePSM (Engineering phosphate solubilization microorganisms and deciphering the mechanism of phosphate solubilization during plant-microbe interactions)

Reporting period: 2023-04-01 to 2025-03-31

Summary of the context and overall objectives of the project

This MSCA-funded ePSM project aimed to systematically investigate the potential of phosphate-solubilizing microbes (PSMs) in agricultural systems using cutting-edge technologies. The primary objective was to address the longstanding question of whether PSMs can effectively promote plant growth and increase crop yields under natural soil conditions. The project was designed to bridge the gap between laboratory findings and real-world agricultural applications, thereby contributing to sustainable agriculture. The expected impacts of the project are significant, offering both scientific insights into the functions and mechanisms of PSMs and practical implications for enhancing crop productivity through microbiome-based strategies.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The major scientific and technical activities of the project included:

a. Development of a high-throughput screening method: A robust in vitro high-throughput method was established to screen PSMs. A total of 681 bacterial isolates were screened from the root microbiomes of soybean (268 isolates), Arabidopsis thaliana (192 isolates), and Lotus japonicus (221 isolates). Approximately 40% of these isolates demonstrated phosphate-solubilizing capabilities.

b. Distribution across plant species: PSMs were found to be widespread members of root microbiota across diverse plant hosts.

c. Taxonomic identification: The most prominent PSM taxa were identified as belonging to the Comamonadaceae and Pseudomonadaceae families.

d. Impact on crop yield: Root-associated PSMs were shown to enhance soybean yield in a soil-type-dependent manner.

e. Key functional strains: Specific strains from the Comamonadaceae family significantly promoted soybean production in natural soils, particularly when co-inoculated with Bradyrhizobium.

f. Environmental stability: The yield-enhancing effects of PSMs were found to be influenced by environmental variables, such as soil type and moisture.

g. Root microbiome dynamics: The soybean root microbiome displayed dynamic temporal shifts shaped by environmental conditions.

h. Colonization dynamics: The persistence of PSM colonization in natural soils was shown to be both strain-specific and niche-dependent.

i. Mechanism of action: The mechanism of phosphate solubilization in Comamonadaceae and Pseudomonadaceae was linked to activation of the phosphate starvation (Pi hunger) response pathway.

j. In situ tracking: Strain-specific probes were developed and used to track PSMs in soil, revealing that long-term persistence was primarily limited to strains within the Comamonadaceae family.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

1.Identification of high-performing, root-associated PSM strains for yield enhancement
The project identified specific strains from the Comamonadaceae family that consistently enhanced soybean yield in a soil-type-dependent manner. This finding advances the state of the art by linking microbial taxonomy to agronomic performance under natural conditions. To ensure further uptake, future research should focus on large-scale field validation across diverse agroecological zones, followed by demonstration trials to facilitate farmer and stakeholder adoption. Additionally, Intellectual Property Rights (IPR) support and strain patenting may be necessary to enable commercialization.

2.Mechanistic understanding of phosphate solubilization and strain persistence
The project revealed that PSM function is linked to activation of the phosphate starvation response and that long-term colonization is strain- and niche-specific. These mechanistic insights are critical for the development of next-generation biofertilizers with stable field performance. To enable broader impact, standardization of microbial screening protocols and the development of a regulatory framework for microbial product approval in the EU would be essential. International collaboration and alignment of standards will also be important for successful market entry and scalability.