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Celery ( Apium graveolens ) parenchyma cell walls: cell walls with minimal xyloglucan
Author(s) -
Thimm Julian C.,
Burritt David J.,
Sims Ian M.,
Newman Roger H.,
Ducker William A.,
Melton Laurence D.
Publication year - 2002
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2002.1160205.x
Subject(s) - xyloglucan , apium graveolens , cell wall , cellulose , chemistry , glycosyl , polysaccharide , galactan , carbon 13 nmr , solid state nuclear magnetic resonance , microfibril , crystallography , nuclear magnetic resonance , stereochemistry , biochemistry , botany , biology , physics
The primary walls of celery ( Apium graveolens L.) parenchyma cells were isolated and their polysaccharide components characterized by glycosyl linkage analysis, cross‐polarization magic‐angle spinning solid‐state 13 C nuclear magnetic resonance (CP/MAS 13 C NMR) and X‐ray diffraction. Glycosyl linkage analysis showed that the cell walls consisted of mainly cellulose (43 mol%) and pectic polysaccharides (51 mol%), comprising rhamnogalacturonan (28 mol%), arabinan (12 mol%) and galactan (11 mol%). The amounts of xyloglucan (2 mol%) and xylan (2 mol%) detected in the cell walls were strikingly low. The small amount of xyloglucan present means that it cannot coat the cellulose microfibrils. Solid‐state 13 C NMR signals were consistent with the constituents identified by glycosyl linkage analysis and allowed the walls to be divided into three domains, based on the rigidity of the polymers. Cellulose (rigid) and rhamnogalacturonan (semi‐mobile) polymers responded to the CP/MAS 13 C NMR pulse sequence and were distinguished by differences in proton spin relaxation time constants. The arabinans, the most mobile polymers, responded to single‐pulse excitation (SPE), but not CP/MAS 13 C NMR. From solid‐state 13 C NMR of the cell walls the diameter of the crystalline cellulose microfibrils was determined to be approximately 3 nm while X‐ray diffraction of the cell walls gave a value for the diameter of approximately 2 nm.