Multi-Omics Reveal the Efficient Phosphate-Solubilizing Mechanism of Bacteria on Rocky Soil.

Yanling Jin,Zhuolin Yi,Yang Fang,Sulan He,Kaize He,Yuming Li,Hai Zhao,Yanqiang Ding

doi:10.3389/fmicb.2021.761972

Abstract

Phosphate-solubilizing bacteria (PSB) can alleviate available phosphorus (AP)-deficiency without causing environmental pollution like chemical phosphate fertilizers. However, the research and application of PSB on the barren rocky soil is very rare. We screened six PSB from sweetpotato rhizosphere rocky soil. Among them, Ochrobactrum haematophilum FP12 showed the highest P-solubilizing ability of 1,085.00 mg/L at 7 days, which was higher than that of the most reported PSB. The assembled genome of PSB FP12 was 4.92 Mb with P-solubilizing and plant growth-promoting genes. In an AP-deficient environment, according to transcriptome and metabolomics analysis, PSB FP12 upregulated genes involved in gluconic acid synthesis and the tricarboxylic acid cycle, and increased the concentration of gluconic acid and malic acid, which would result in the enhanced P-solubilizing ability. Moreover, a series of experiments in the laboratory and field confirmed the efficient role of the screened PSB on significantly increasing AP in the barren rocky soil and promoting sweetpotato yield. So, in this study, we screened highly efficient PSB, especially suitable for the barren rocky soil, and explored the P-solubilizing mechanism. The research will reduce the demand for chemical phosphate fertilizers and promote the environment-friendly agricultural development.

Highlights

Available phosphorus (AP) is deficient in 74% of the arable soil of China and in more than 40% of the arable soil globally, because about 99% of the total phosphorus (TP) is dissolved (Balemi and Negisho, 2012; Yu et al, 2019)
The P-solubilizing circle of phosphate-solubilizing bacteria (PSB) FP12 was observed with a large diameter of 23.75 mm and diameter of the round hole (D/d) of 3.96 (Supplementary Table S2)
We found that the pH of the insoluble and available P medium (IAPM) and available P medium (APM) group media were significantly higher than those of the insoluble P medium (IPM) and no P medium (NPM) group media (Figure 1A), indicating that available phosphorus (AP) might weaken the acidification of PSB FP12

Summary

Introduction

Available phosphorus (AP) is deficient in 74% of the arable soil of China and in more than 40% of the arable soil globally, because about 99% of the total phosphorus (TP) is dissolved (Balemi and Negisho, 2012; Yu et al, 2019). This leads to a huge demand for chemical phosphate fertilizers. Developing methods to reduce the demand for chemical phosphate fertilizers and improve the bioavailability of soil TP is of significance to both agricultural production and environmental protection. Considering possible effects of the different organic matter, pH, and other characteristics of the soil on the colonization and function of PSB, it is very necessary to develop suitable PSB for different types of soil

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