Characteristics of Organic Acid Secretion Associated with the Interaction betweenBurkholderia multivoransWS-FJ9 and Poplar Root System

Abstract

The objective of this study was to investigate whether plant-bacteria interaction affects the secretion of organic acids by both organisms and to assess whether the production of IAA by the bacterium increases the secretion of organic acids by root exudates, and if the stress produced by low available phosphorus (P) affects the production of organic acids by bacteria, by roots, or by root exudates in presence of bacterial cultures. With this purpose, we used as a biological model poplar plants and one strain ofBurkholderia multivoransable to solubilize P. High performance liquid chromatography was utilized to measure organic acids. The tests, the inductive effects of exogenous indole-3-acetic acid (IAA) on secretion of organic acids, the 2 × 4 × 2 factorial design experiment, and the ability of organic acids to solubilize tricalcium phosphate were performed to investigate the interactive effects. The results showed that, afterB. multivoransWS-FJ9 interacted with the poplar root system, the key phosphate-solubilizing driving force was gluconic acid (GA) which was produced in three ways: (1) secreted by the root system in the presence of IAA produced byB. multivoransWS-FJ9; (2) secreted byB. multivoransWS-FJ9; and (3) secreted by the poplar root system in the presence of phosphorus stress. When phosphorus stress was absent, the GA was produced as outlined in (1) and (2) above. These results demonstrated that inoculatingB. multivoransWS-FJ9 into the poplar root system could increase the amount of GA secretion and implied that the interaction betweenB. multivoransWS-FJ9 and the poplar root system could contribute to the increase of P available fraction for poplar plants.