Minisymposium 16: Cell walls

Abs # 31005: Characterization of dynamic alterations in cell wall architecture of maize and Arabidopsis by Fourier transform infrared and near infrared spectroscopy

Presenter:	Carpita, Nick , carpita@purdue.edu
Authors	Carpita, Nick  (A)   Langewisch, Tiffany L (A)   Mills, K Maria  (B)   Urbanowicz, Breeanna R (A)   Defernez, Marianne  (C)   Yong, Weidong  (A)   Link, Bruce  (D)   O'Malley, Ronan  (E)   Binder, Brad  (F)   Tewari, Jagdish  (B)   Olek, Anna  (A)   Bleecker, Tony  (E)   Koch, Karen  (G)   McCarty, Don  (G)   Reiter, Wolf-Dieter  (D)   Patterson, Sara  (F)   Thomas, Steven  (H)   Vermerris, Wilfred  (I)   McCann, Maureen  (B)
Affiliations:	(A): Department of Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-2054 (B): Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2054 (C): Department of Food Metrology, Institute of Food Research, Colney, Norwich NRA 7UA, United Kingdom (D): Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3125 (E): Department of Botany, University of Wisconsin, Madison, WI 53706 (F): Department of Horticulture, University of Wisconsin, Madison, WI 53706 (G): Horticultural Sciences Department, University of Florida, Gainesville, FL 32611 (H): National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401 (I): Departments of Agronomy and Agricultural & Biological Engineering, Purdue University, West Lafayette, IN47907-2054
Web Site:	http://www.btny.purdue.edu/faculty/carpita

Discriminant analysis of Fourier transform infrared (FTIR) and near infrared (NIR) spectra have been developed as high through-put methods to identify mutations in maize and Arabidopsis cell wall polysaccharide components and wall architecture. Robot-assisted, high through-put PCR protocols have been developed to obtain homozygous T-DNA tagged lines of Arabidopsis (see http://cellwall.genomics.purdue.edu and links therein). Maize lines carrying segregating sequence-tagged Mu-insertions introgressed into the inbred W22 were generated and used as primary material for mutation screens. In both instances, disrupted genes of mutants are identified based on the position of the insertional element. Reverse-genetics DNA grids representing nearly 20,000 lines are being developed to identify those with Mu elements near cell-wall relevant genes of interest. Existing Arabidopsis cell-wall mutants serve as valuable resources to define the spectral deviations observed by FTIR spectra between cell walls of wild-type and mutant. Mutations in several cellulose synthases and a membrane-associated endo-β-D-glucan hydrolase give distinctive spectra that show that pectin molecules are enriched specifically in cellulose-deficient backgrounds and remain oriented despite low cellulose content. Mutations that alter xyloglucan side-chain composition give spectral signatures that are traced to architectural features in cellulose-xyloglucan interaction that are revealed specifically in elongating cells. In contrast to Arabidopsis, maize has type II cell walls, which are composed of cellulose microfibrils, glucuronoarabinoxylans (GAXs) of varying degrees of side-group substitution, and mixed-linkage (1,3),(1,4)-β-D-glucans (β-glucans) woven together with a complex network of phenylpropanoids. Several discriminant analysis and class modeling algorithms were employed to identify characteristic spectral signatures permitting quantitation of cellulose, GAXs, β-glucan, and the four major monosaccharides, arabinose, xylose, glucose and galactose. These infrared “spectrotypes” provide a novel way to characterize additional mutants that arise from mutant screens employing discriminant analysis of infrared spectra. Supported by the NSF Plant Genome Research and REU Programs