Direct Observation of Cell Wall Structure in Living Plant Tissues by Solid-State 13C NMR Spectroscopy

Abstract

Solid-state 13C nuclear magnetic resonance (NMR) spectra of the following intact plant tissues were recorded by the cross-polarization magic-angle spinning technique: celery (Apium graveolens L.) collenchyma; carob bean (Ceratonia siliqua L.), fenugreek (Trigonella foenum-graecum L.), and nasturtium (Tropaeolum majus L.) endosperm; and lupin (Lupinus polyphyllus Lindl.) seed cotyledons. All these tissues had thickened cell walls which allowed then to withstand the centrifugal forces of magic angle spinning and which, except in the case of lupid seeds, dominated the NMR spectra. The celery collenchyma cell walls gave spectra typical of dicot primary cell walls. The carob bean and fenugreek seed spectra were dominated by resonances from galactomanans, which showed little sign of crystalline order. Resonances from .beta.(1,4'')-D galactan were visible in the lupin seed spectrum, but there was much interference from protein. The nasturtium seed spectrum was largely derived from a xyloglucan, in which the conformation of the glucan core chain appeared to be intermediate between the solution form and solid forms of cellulose.