Abstract
Plant growth-promoting rhizobacteria (PGPR) play a crucial role in biological control and pathogenic defense on and within plant tissues, however the mechanisms by which plants associate with PGPR to elicit such beneficial effects need further study. Here, we present time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging of Brachypodium distachyon (Brachypodium) seeds with and without exposure to two model PGPR, i.e., Gram-negative Pseudomonas fluorescens SBW25 (P.) and Gram-positive Arthrobacter chlorophenolicus A6 (A.). Delayed image extraction was used to image PGPR-treated seed sections to reveal morphological changes. ToF-SIMS spectral comparison, principal component analysis (PCA), and two-dimensional (2D) imaging show that the selected PGPR have different effects on the host seed surface, resulting in changes in chemical composition and morphology. Metabolite products and biomarkers, such as flavonoids, phenolic compounds, fatty acids, and indole-3-acetic acid (IAA), were identified on the PGPR-treated seed surfaces. These compounds have different distributions on the Brachypodium seed surface for the two PGPR, indicating that the different bacteria elicit distinct responses from the host. Our results illustrate that ToF-SIMS is an effective tool to study plant-microbe interactions and to provide insightful information with submicrometer lateral resolution of the chemical distributions associated with morphological features, potentially offering a new way to study the mechanisms underlying beneficial roles of PGPR.
Original language | English |
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Pages (from-to) | 5855-5865 |
Number of pages | 11 |
Journal | Analyst |
Volume | 146 |
Issue number | 19 |
DOIs | |
State | Published - Oct 7 2021 |
Externally published | Yes |
Funding
R. Komorek and X.-Y. Yu thank the Environmental and Biological Science Directorate (EBSD) mission seed Laboratory Directed Research and Development for initial support of culture and experimental effort. Funding was from the Pacific Northwest National Laboratory (PNNL) W. R. Wiley Environmental Molecular Sciences Laboratory (EMSL) Strategic Science Area of Intercellular Thrust. A portion of the research was performed using EMSL (grid.436923.9), a DOE Office of Science User Facility sponsored by the Office of Biological and Environmental Research under the general EMSL user proposals 50093 and 50170. Y. Zhang thanks Chinese Science Council and the PNNL Alternative Sponsored Fellowship (ASF) for the graduate student fellowship. PNNL is operated by Battelle Memorial Institute for the U.S. DOE under Contract No. DE-AC05-76RL01830.