It is well appreciated that plants have roots which serve many essential functions, such as structurally supporting the plant and taking up nutrients from the soil to promote the growth of the plant. But what is not clear is the chemical composition of different root compartments and how these chemicals are used to signal the growth of the plant. The research team hopes to discover the identity and function of these chemical compounds by making a chemical map of where these chemical compounds are located in the root structure. They will do that by directing a stream of tiny droplets onto a cut section of the root and letting the resulting droplet splash enter a mass spectrometer, a device that can determine the identity and the amount of each compound dissolved in the scattered droplets. By mounting the root section on a slide that be moved right and left as well as up and down, a two-dimensional map will be recorded of the compounds present in the root. They believe this approach will provide new information related to how roots of plants function.
Metabolite and lipid signaling molecules are critical for proper regulation of development in multicellular organisms. The chemical properties of these small molecules enable them to cross cell membranes, function as highly specific ligands to protein receptors, and dynamically convert between different molecular species on short time scales. These abilities facilitate rapid communication of developmental cues across tissues. Defects in the biosynthesis, perception, or metabolism of these compounds can lead to aberrant tissue formation and disease. Despite the critical importance of small molecules, most of our understanding of their function is derived from indirect measurements of these compounds. The investigators will utilize desorption electrospray ionization mass spectrometry imaging (DESI-MSI) to directly measure small molecules in distinct developmental regions of root tissue. The root meristem is an excellent model for this work because cells are organized along a longitudinal developmental gradient, with pluripotent stem cells located at the tip of the root, and differentiated cells localized towards the direction of the shoot. This approach is yielding the identification of novel small molecule regulators of development. Combining DESI-MSI with traditional molecular biology approaches will enable characterization of new roles of metabolite and lipid signaling compounds in stem cell decisions, with implications in both plant and human research.
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