Record ID No. |
5676 |
Author(s) |
Shinde S.*, Zerbs S., Collart F. R., Cumming J. R., Noirot P. and Larsen P. E. , 2019 |
Affiliation |
*Argonne National Laboratory, Biosciences Division, 9700 S. Cass Ave., Argonne, IL 60439, USA. |
Title |
Pseudomonas fluorescens increases mycorrhization and modulates expression of antifungal defense response genes in roots of aspen seedlings. |
Source. Vol.(no):Page |
BMC Plant Biology. 19(4). |
Categories |
|
Subjects |
Biological Interaction Ecology Genetics |
Sub-subjects |
Mycorrhiza helper bacteria |
Host |
Populus tremuloides |
Organism |
Laccaria bicolor, Pseudomonas fluorescens |
Country |
USA |
Abstracts |
Plants, fungi and bacteria form complex, mutually-beneficial communities within the soil environment. One role that bacteria play in these communities is that of mycorrhizal helper bacteria (MHB). The specific molecular mechanisms by which MHB drive gene regulation in plant roots leading to various benefits remain largely uncharacterized. In the study, the effects of the bacterium Pseudomonas fluorescens SBW25(SBW25) on aspen root transcriptome was investigated, using a tripartite laboratory community comprised of Populus tremuloides (Aspen seedlings) and the ectomycorrhizal fungus Laccaria bicolor. It has been shown that SBW25 has MHB activity and promotes mycorrhization of aspen roots by Laccaria. Using transcriptomic analysis of aspen roots under multiple community compositions, clusters of co-regulated genes associated with mycorrhization, the presence of SBW25, and MHB-associated functions were identified, and a combinatorial logic network that links causal relationships in observed patterns of gene expression in aspen seedling roots in a single Boolean circuit diagram was generated. The predicted regulatory circuit was used to infer regulatory mechanisms associated with MHB activity. In our laboratory conditions, SBW25 increased the ability of Laccaria to form ectomycorrhizal interactions with aspen seedling roots through the suppression of aspen root antifungal defense responses. Analysis of transcriptomic data identified that potential molecular mechanisms in aspen roots that respond to MHB activity were proteins with homology to pollen recognition sensors. Pollen recognition sensors integrate multiple environmental signals to down-regulate pollenization-associated gene clusters, making proteins with homology to this system an excellent fit for a predicted mechanism that integrates information from the rhizosphere to down-regulate antifungal defense response genes in the root. These results provide a deeper understanding of aspen gene regulation in response to MHB and suggest additional, hypothesis-driven biological experiments to validate putative molecular mechanisms of MHB activity in the aspen-Laccaria ectomycorrhizal symbiosis. |