PLANT PHYSIOLOGY , Vol 115, Issue 2 587-592, Copyright © 1997 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Estimation of Polymer Rigidity in Cell Walls of Growing and Nongrowing Celery Collenchyma by Solid-State Nuclear Magnetic Resonance in Vivo
K. M. Fenwick, M. C. Jarvis and D. C. Apperley
Chemistry Department, Glasgow University, Glasgow G12 8QQ, Scotland, United Kingdom (K.M.F., M.C.J.)
When the growth of a plant cell ceases, its walls become more rigid and
lose the capacity to extend. Nuclear magnetic resonance relaxation methods
were used to determine the molecular mobility of cell wall polymers in
growing and nongrowing live celery (Apium graveolens L.) collenchyma. To
our knowledge, this is the first time this approach has been used in vivo.
Decreased polymer mobility in nongrowing cell walls was detected through
the 13C-nuclear magnetic resonance spectrum by decreases in the proton
spin-spin relaxation time constant and in the intensity of a sub-spectrum
corresponding to highly mobile pectins, which was obtained by a spectral
editing technique based on cross-polarization rates. Flexible, highly
methyl-esterified pectins decreased in relative quantity when growth
ceased. A parallel increase in the net longitudinal orientation of
cellulose microfibrils was detected in isolated cell walls by polarized
Fourier-transformed infrared spectrometry.
