The limited availability of soil phosphorus to plants under salinity stress is a major constraint for crop production in saline soils, which could be alleviated by improving mycorrhizal and soil microbial interactions. This study investigated the effects of
Funneliformis mosseae (
Fm) inoculation on phosphorus (P) availability to
Sorghum bicolor, and alkaline phosphatase (ALP) activity and gene abundance (
phoD) in a P-deficient naturally saline soil. A greenhouse study was conducted in order to compare the experimental treatments of
Fm inoculated vs. control plants grown in saline soil with and without (sterilized soil) native microbial community. A separate hyphosphere (root-free) compartment was constructed within the mycorrhizosphere and amended with phosphate. After four weeks of transplanting, shoot, roots, mycorrhizosphere, and hyphosphere samples were collected and analyzed for soil and plant P concentrations, root colonization, and abundance of ALP and
phoD. The results showed significantly higher colonization in
Fm-inoculated treatments compared to uninoculated. Plant available P concentrations,
phoD gene abundance and ALP activity were significantly reduced (
p < 0.05) in sterilized-hyphosphere as compared to unsterilized in both
Fm-inoculated and uninoculated treatments. Inoculation with
Fm significantly increased the plant P uptake (
p < 0.05) when compared to uninoculated treatments, but only in the plants gown in unsterile mycorrhizosphere. It can be concluded that inoculation of
Fm increased root colonization and the uptake of P by sorghum plant in saline soil and native microbial community interactions were critical for increasing bioavailable P concentrations. These beneficial interactions between plants, mycorrhizae, and native microbes should be considered for soil fertility management in saline soils.
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