AFM Investigations of Cellulose Fibers in Bintje Potato (Solanum tuberosum L.) Cell Wall Fragments

Abstract

Atomic force microscopy (AFM) has been used to image the cellulose networks in moist fragments of the cell walls of Bintje potato (Solanum tuberosum L.). The interfiber spacing in hydrated native cell wall fragments was found to be 26.2 nm. This value is consistent with published estimates of the contour length of xyloglucan cross-links determined by transmission electron microscopy (TEM) studies of cell walls. Sequential extraction of the pectin using CDTA and Na2CO3 led to shrinkage of the cell wall fragment and a reduction in interfiber spacing to 20.2 nm. Partial extraction of xyloglucan using 1 M KOH caused a small decrease in interfiber spacing to 19.5 nm. Finally, the almost complete removal of xyloglucan with 4 M KOH substantially reduced the interfiber spacing to 11 nm. The results are consistent with a model for the cell wall in which the cellulose–xyloglucan network is immersed in a swollen, hydrated pectin network.