title: Chemical stimulation of the Arabidopsis thaliana root using multi-laminar flow on a microfluidic chip.
abstract: In this article, we developed a "plant on a chip" microfluidic platform that can control the local chemical environment around live roots of Arabidopsis thaliana with high spatial resolution using multi-laminar flow. We characterized the flow profile around the Arabidopsis root, and verified that the shear forces within the device ( approximately 10 dyne cm(-2)) did not impede growth of the roots. Our platform was able to deliver stimuli to the root at a spatial resolution of 10-800 microm. Further, the platform was validated by exposing desired regions of the root with a synthetic auxin derivative, 2,4-dichlorophenoxyacetic acid (2,4-D), and its inhibitor N-1-naphthylphthalamic acid (NPA). The response to the stimuli was observed using a DR5::GFP Arabidopsis line, where GFP expression is coupled to the auxin response regulator DR5. GFP expression in the root matched the position of the flow-focused stream containing 2,4-D. When the regions around the 2,4-D stimulus were exposed to the auxin transport inhibitor NPA, the active and passive transport mechanisms of auxin could be differentiated, as NPA blocks active cell-to-cell transport of auxin. Finally, we demonstrated that local 2,4-D stimulation in a approximately 10 microm root segment enhanced morphological changes such as epidermal hair growth. These experiments were proof-of-concept and agreed with the results expected based on known root biology, demonstrating that this "root on a chip" platform can be used to test how root development is affected by any chemical component of interest, including nitrogen, phosphate, salts, and other plant hormones.
authors.affiliation: Department of Chemistry and Institute for Biophysical Dynamics, The University of Chicago, 929 E. 57th Street, Chicago, IL, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Meier
authors.forename: Elena M
authors.initials: EM
authors.lastname: Lucchetta
authors.forename: Rustem F
authors.initials: RF
authors.lastname: Ismagilov
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development*; D004867:Equipment Design; D049452:Green Fluorescent Proteins / Q000378:metabolism; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D010797:Phthalimides / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development*; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence; D013268:Stimulation, Chemical
chemical_list: D010797:Phthalimides; D010937:Plant Growth Regulators; D049452:Green Fluorescent Proteins; D015084:2,4-Dichlorophenoxyacetic Acid; C002687:alpha-naphthylphthalamic acid