ToF-SIMS Analysis of Plant Seed Interactions with Plant Growth-Promoting Bacteria

The use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) in plant biology is a relatively unexplored and quickly developing field. The majority of research in plant SIMS involves the application of ToF-SIMS to study dried wood tissues, and only a handful of studies apply SIMS on plant stems, roots, and/or seeds. Our project provides a brief description and review of previous work using SIMS on plant stems, roots, and/or seeds, along with an emphasis on the sample preparation in each study. Additionally, the use of Brachypodium distachyon (Brachypodium) as a model system for research on grasses has also become more prominent in plant biology. However, a review of the literature shows no previous work using ToF-SIMS to study the model plant, B. distachyon, has been done. This is of interest to use because Brachypodium as a model plant can provide insight on the biological studies of other C3 grasses, including small grain crops such as wheat and barley. Therefore, the interaction of grains of Brachypodium with a plant growth-promoting bacteria (PGPB), Pseudomonas, was characterized and chemically imaged using ToF-SIMS. The use of the delayed image extraction in ToF-SIMS provides chemical speciation of the Brachypodium seed surface and simultaneously captures the morphological features of the plant-bacteria model. This work provides an initial characterization of fatty acids (stearic acid, palmitic acid, and arachidic acid) present on the Brachypodium seed surface