Making Plant Cells Work Like Miniature Factories

Now, a group of researchers at the U.S. Department ofEnergy’s Ames Laboratory at Iowa State University will use $1.02million in DOE start-up funding to begin understanding the chemicalprocesses that take place within the cells of plants. This new field,called metabolomics, could result in harnessing plants to efficientlyproduce biomass for energy production, chemicals and materials forindustry or pharmaceuticals, and untold thousands of other uses.

“Weknow a lot about the genetic make-up of many plants, but we know verylittle about the chemical changes that take place within plant cellsthat eventually produce sugars, fibers or waxes,” said Ed Yeung,program director of Chemical and Biological Sciences at Ames Lab andprincipal investigator on the project. “If we can understandmetabolism, then ideally, all the materials a plant produces can becontrolled.”

The project, “Mass Spectrometric Imaging of PlantMetabolites,” combines the analytical chemistry expertise of AmesLaboratory with the strength of ISU’s Plant Sciences Institute. Yeung,who is also a distinguished professor of chemistry at ISU, isinternationally recognized for his work in developing separation anddetection technologies, having won four R&D 100 awards.

Alsoworking on the project are Sam Houk, an Ames Lab senior chemist whospecializes in identifying trace elements using inductively coupleplasma-mass spectrometry, and associate scientist and ISU chemistryprofessor Ethan Badman, who specializes in mass spectrometry andgas-phase methods of analysis for biological molecules. Rounding outthe team is Basil Nikolau, Director of the Plant Sciences Institute’sCenter for Designer Crops and a specialist in biochemistry andfunctional genomics of plant metabolism.

Funding from theChemical Sciences, Geosciences and Biosciences Division of the DOE’sOffice of Basic Energy Sciences provides $340,000 for operation andequipment this year and another $680,000 in 2006. Additional money isexpected in 2007 and could continue if the program receives good marksduring a peer review scheduled for 2008.
Before they can study thechemical makeup within plant cells, the team must construct newanalytical instruments capable of identifying molecules in such minutequantities.

“Developing the instrumentation is a large part ofthe proposal and we’re building a special, high-resolution massspectrometer,” Yeung said, “because there’s nothing availablecommercially that meets our needs.” He added that the equipment will behoused in the Roy J. Carver Co-Laboratory on the ISU campus.

Massspectrometry works by measuring the mass of individual ions – moleculesthat have been electrically charged. Plant material is ionized into agas, sorted in an analyzer chamber according to the mass-to-chargeratios, and collected by an ion detector. The detector converts ionflux into a proportional electrical current. Finally, the magnitude ofthe electrical signals is recorded and plotted as a mass spectrum.

The ability to sort and detect these ions at cellular-scale quantities is where the team hopes to fine-tune the instrumentation.

Oncethe equipment is ready, the team will look at the chemical content inthe cells of Arabidopsis thaliana, a small flowering plant that iswidely used as a model organism in plant biology. Arabidopsis is amember of the mustard (Brassicaceae) family, which includes cultivatedspecies such as cabbage and radish.

“Arabidopsis is not a majorcrop like corn and soybeans,” Yeung said, “but because so much isalready known about it genetically, we can hopefully begin to drawcorrelations between the chemical and genetic makeup. We hope that suchfundamental research will be applicable to other plants as well.”

AmesLaboratory is operated for the Department of Energy by Iowa StateUniversity. The Lab conducts research into various areas of nationalconcern, including energy resources, high-speed computer design,environmental cleanup and restoration, and the synthesis and study ofnew materials.