Root exudate-derived compounds stimulate the phosphorus solubilizing ability of bacteria

Scientific Reports, vol. 13, pp. 4050

Abstract

Low phosphorus (P) availability in soils is a major challenge for sustainable food production, as most soil P is often unavailable for plant uptake and effective strategies to access this P are limited. Certain soil occurring bacteria and root exudate-derived compounds that release P are in combination promising tools to develop applications that increase phosphorus use efficiency in crops. Here, we studied the ability of root exudate compounds (galactinol, threonine, and 4-hydroxybutyric acid) induced under low P conditions to stimulate the ability of bacteria to solubilize P. Galactinol, threonine, and 4-hydroxybutyric acid were incubated with the P solubilizing bacterial strains Enterobacter cloacae, Pseudomonas pseudoalcaligenes, and Bacillus thuringiensis under either inorganic (calcium phosphate) or organic (phytin) forms of plant-unavailable P. Overall, we found that the addition of individual root exudate compounds did not support bacterial growth rates. However, root exudates supplemented to the different bacterial appeared to enhance P solubilizing activity and overall P availability. Threonine and 4-hydroxybutyric acid induced P solubilization in all three bacterial strains. Subsequent exogenous application of threonine to soils improved the root growth of corn, enhanced nitrogen and P concentrations in roots and increased available levels of potassium, calcium and magnesium in soils. Thus, it appears that threonine might promote the bacterial solubilization and plant-uptake of a variety of nutrients. Altogether, these findings expand on the function of exuded specialized compounds and propose alternative approaches to unlock existing phosphorus reservoirs of P in crop lands.

Authors 4

1. Hugo A. Pantigoso Aachen Institute of Biology, Leiden University

   Leiden University · Colorado State University

   Affiliation as printed

   Department of Horticulture and Landscape Architecture, Center for Root and Rhizosphere Biology, Colorado State University, Fort Collins, CO, USA

   Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, Netherlands

2. Daniel K. Manter

   United States Department of Agriculture · Agricultural Research Service - Plains Area

   Affiliation as printed

   United States Department of Agriculture - Agricultural Research Services, Soil Management and Sugar Beet Research, Fort Collins, CO, USA

   United States Department of Agriculture – Agricultural Research Services, Soil Management and Sugar Beet Research, Fort Collins, CO, USA

3. Steven J. Fonte

   Colorado State University

   Affiliation as printed

   Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO, USA

4. Jorge M. Vivanco corresponding

   Colorado State University

   Affiliation as printed

   Department of Horticulture and Landscape Architecture, Center for Root and Rhizosphere Biology, Colorado State University, Fort Collins, CO, USA. j.vivanco@colostate.edu

   Department of Horticulture and Landscape Architecture, Center for Root and Rhizosphere Biology, Colorado State University, Fort Collins, CO, USA