Infection of Soybean Plants with the Insect Bacterial Symbiont Burkholderia gladioli and Evaluation of Plant Fitness

Abstract

To investigate the establishment and consequences of host-microbe interactions, it is important to develop controlled infection assays suitable for each system, as well as appropriate methods to evaluate successful infection and its associated effects. Here, we describe a procedure for bacterial inoculation of soybean plants, followed by the assessment of systemic infection and impact on plant fitness. Soybean (Glycine max) seedlings were mechanically wounded using a device that mimics insect herbivory and inoculated with known cell numbers of Burkholderia gladioli bacteria previously isolated from an insect host. The impact on the plants was evaluated by monitoring changes in height, time to flowering and chlorophyll content during plant development, and by quantifying seed production in comparison to plants inoculated with sterile water. The presence and proliferation of bacterial infection were examined in tissues from developed plants using quantitative PCR and fluorescence in situ hybridization (FISH).