Interactions of Arbuscular Mycorrhizal Fungi with Hyphosphere Microbial Communities in a Saline Soil: Impacts on Phosphorus Availability and Alkaline Phosphatase Gene Abundance

Abdurrahman Masrahi,Terry Gentry,Anil Somenahally

doi:10.3390/soilsystems4040063

Abdurrahman Masrahi, Terry Gentry + Show 1 more

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https://doi.org/10.3390/soilsystems4040063

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Journal: Soil Systems	Publication Date: Oct 22, 2020
Citations: 4	License type: CC BY 4.0

Affiliation: Texas A&M University, Jazan University

Abstract

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.

Highlights

Saline soils occur on more than 10% of Earth’s land surface [1], impacting agriculture productivity worldwide [1,2]
It can be concluded that inoculation of Funneliformis mosseae (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
The percentages of AMF root colonization (Table 2) were significantly higher (p < 0.0001) in Fm-inoculated IS-OS and IU-OU treatments as compared to all uninoculated treatments, while Fm-inoculated inner sterilized and outer unsterilized (IS-OU) and inner unsterilized and outer sterilized (IU-OS) were significantly higher only compared to uninoculated IS-OS

Summary

Introduction

Saline soils occur on more than 10% of Earth’s land surface [1], impacting agriculture productivity worldwide [1,2]. The application of plant beneficial microbes, such as AMF, have proven to be effective in improving plant growth [8,9], especially under salt stress where the abundance of AMF is generally low [10] Such enhancement of plant growth has been attributed to the production of phytohormones [11], improvements in N-fixation [12], and P-solubilization [13,14] by plant growth promoting rhizobacteria (PGPR), and improved soil structure and water uptake [15], P uptake [16,17], and increased K+ /Na+ plant ratio [17,18] by AMF

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