title: Rethinking how volatiles are released from plant cells.
abstract: For plant volatile organic compounds (VOCs) to be emitted, they must cross membrane(s), the aqueous cell wall, and sometimes the cuticle, before moving into the gas phase. It is presumed that VOC movement through each barrier occurs via passive diffusion. However, VOCs, which are primarily nonpolar compounds, will preferentially partition into membranes, making diffusion into aqueous compartments slow. Using Fick's first law, we calculated that to achieve observed VOC emission rates by diffusion alone would necessitate toxic VOC levels in membranes. Here, we propose that biological mechanisms, such as those involved in trafficking other hydrophobic compounds, must contribute to VOC emission. Such parallel biological pathways would lower barrier resistances and, thus, steady-state emission rates could be maintained with significantly reduced intramembrane VOC concentrations.
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN 47907-2063, USA.
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Widhalm
authors.affiliation: School of Chemical Engineering, Purdue University, 480 Stadium Mall Dr., West Lafayette, IN 47907-2100, USA.
authors.forename: Rohit
authors.initials: R
authors.lastname: Jaini
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN 47907-2063, USA; School of Chemical Engineering, Purdue University, 480 Stadium Mall Dr., West Lafayette, IN 47907-2100, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Morgan
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN 47907-2063, USA; Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr., West Lafayette, IN 47907-2010, USA. Electronic address: dudareva@purdue.edu.
authors.forename: Natalia
authors.initials: N
authors.lastname: Dudareva
mesh_terms: D004058:Diffusion; D008954:Models, Biological; D059828:Plant Cells / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D055549:Volatile Organic Compounds
keywords: diffusion; emission; phenylpropanoids/benzenoids; terpenoids; trafficking; volatile organic compound (VOC)