Poster: Cell walls

Abs # 620: Discriminant analysis of Fourier transform infrared spectra of cell wall mutants provide “spectrotypes” that define specific alterations in the synthesis and assembly of cellulose and matrix polysaccharides

Presenter:	McCann, Maureen C, mmccann@bilbo.bio.purdue.edu
Authors	McCann, Maureen C (A)   Mills, K. Maria  (A)   Yong, Weidong  (B)   Link, Bruce  (C)   O'Malley, Ronan  (D)   Binder, Brad  (D)   Tewari, Jagdish  (A)   Olek, Anna  (B)   Reiter, Wolf-Dieter  (C)   Patterson, Sara  (E)   Bleecker, Tony  (D)   Carpita, Nick  (B)
Affiliations:	(A): Department of Biological Sciences, Purdue University, West Lafayette, IN47907-2054 (B): Department of Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-2054 (C): Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3125 (D): Department of Botany, University of Wisconsin, Madison, WI 53706 (E): Department of Horticulture, University of Wisconsin, Madison, WI 53706

Bioinformatics approaches have identified over 1000 genes in Arabidopsis that function in wall biogenesis and disassembly. Robot-assisted, high through-put PCR protocols have been developed to obtain homozygous lines of Arabidopsis with T-DNA inserts in many of these genes (see http://cellwall.genomics.purdue.edu and links therein). Discriminant analyses of Fourier transform infrared (FTIR) spectra have been developed as high through-put methods to identify cell-wall-related phenotypes from these lines. Existing cell-wall mutants serve as valuable resources to define the spectral deviations observed by FTIR spectra between cell walls of wild-type and mutant plants. 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 and are revealed specifically in elongating cells. A fucose null mutant, mur1, three arabinose-deficient mutants, and a rhamnose-deficient mutant give spectral signatures characteristic of the pectin network enveloping the cellulose-xyloglucan framework. Polarized IR spectra show that the mur1 phenotype can be partially rescued with high boron, with the implication that RG II dimers are required for non-cellulosic polymer orientations. 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