Quantification of bacterial non-specific acid (phoC) and alkaline (phoD) phosphatase genes in bulk and rhizosphere soil from organically managed soybean fields

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 2017-03, Vol.111, p.48-56
• Main Authors: Fraser, Tandra D., Lynch, Derek H., Gaiero, Jonathan, Khosla, Kamini, Dunfield, Kari E.
• Format: Article
• Language: English
• Subjects: Available phosphorus; Bacteria; P-scavenging genes; Phosphatase; Plant P uptake
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2016.11.013

•New primers were designed to study bacterial phoC gene abundance in soil.•Higher abundances of phoC genes compared to phoD across all sites.•Higher phosphatase activity (pH 6.5) in rhizosphere soil.•Soil labile P was negatively correlated with phosphatase activity and phoC and phoD gene abundance.•No relationship between pre-seeding soil test P and plant P uptake or yield. Phosphorus (P) is a limiting nutrient in many environments but plants and microbes have evolved with mechanisms for acquiring soil P, including the excretion of phosphatase enzymes. Molecular analysis of bacterial phosphatase genes can provide insight into biological P transformations and the contribution to soil P availability and plant uptake. To assess these relationships, soil and plant samples were collected from 12 organically-managed soybean fields varying in pH, labile P concentration, and potential phosphatase activity (pH 6.5) across Prince Edward Island, Canada. Real-time PCR was used to quantify bacterial phosphatase genes (phoC and phoD) in bulk and rhizosphere soil. Primers targeting class A (phoC) of the bacterial non-specific acid phosphatases (NSAPs) were designed and confirmed as effectively targeting phoC genes through sequencing, and phylogenetic comparison with acid phosphatase genes from Genbank. Across all sites, we found that labile P in bulk soil was negatively correlated with phoC and phoD gene abundance and phosphatase activity. In addition, phosphatase activity was consistently higher in rhizosphere compared to bulk soil and was significantly correlated with phoC (bulk soil only) and phoD (rhizosphere soil only) gene abundance. A positive relationship was observed between phosphatase activity, nodule weight, and plant P uptake. Quantification of bacterial genes involved in organic P transformations has been limited, with this study providing the first attempt at quantifying phoC genes in field soils.