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.