FOURIER-TRANSFORM RAMAN AND FOURIER-TRANSFORM INFRARED-SPECTROSCOPY -AN INVESTIGATION OF 5 HIGHER-PLANT CELL-WALLS AND THEIR COMPONENTS

Infrared and Raman spectra of sequentially extracted primary cell welt s and their pectic polymers were obtained from five angiosperm plants. Fourier-transform Raman spectrometry was shown to be a powerful tool for the investigation of primary cell-wall architecture at a molecular level, providing complementary information to that obtained by Fourie r-transform infrared microspectroscopy. The use of an extraction proce dure using imidazole instead of cyclohexane trans-1,2-N,N,N',N'-diamin otetraacetate allows the extension of the infrared spectral window for data interpretation from 1300 to 800 cm(-1), to 2000 to 800 cm(-1), a nd allows us to obtain Raman spectra from extracted cell-wall material . Wall constituents such as pectins, proteins, aromatic phenolics, cel lulose, and hemicellulose have characteristic spectral features that c an be used to identify and/or fingerprint these polymers without, in m ost cases, the need for any physical separation. The Gramineae (rice [ Oryza sativa], polypogon [Polypogon fugax steud], and sweet corn [Zee mays]) are spectroscopically very different from the nongraminaceous m onocotyledon (onion [Allium cepa]) and the dicotyledon (carrot [Daucus carota]); this reflects differences in chemical composition and cross -linking of the walls. The possibility of a taxonomic classification o f plant cell walls based on infrared and Raman spectroscopies and the use of spectral fingerprinting for authentication and detection of adu lteration of products rich in cell-wall materials are discussed.