Potato cell wall preparation

Small proportions of 4-linked Xylp residues were found in linkage analyses of potato cell-wall preparations (Ring and Selvendran, 1978) and of 1 M and 4 M KOH soluble extracts (Ring and Selvendran, 1981). At least some of these residues may be present in heteroxylans of primary cell walls. Such heteroxylans are known to occur in small proportions in the primary cell walls of other eudicotyledons, but their structure has been characterized in detail only for those in the walls of suspension-cultured sycamore (Acer pseudoplatanus) cells (Darvill et al., 1980). These heteroxylans are glucuronoarabinoxylans with a backbone of p-D-Xyl/ residues linked... 

Examination of moist, isolated potato cell walls using atomic force microscopy (AFM) showed the cellulose microfibrils as an interwoven network (Kirby et al., 1996,2006). Although accurate height measurements of cellulose microfibrils have not been obtained using AFM on potato cell walls, they have on similar parenchyma cell-wall preparations from onion (Allium cepa) and Arabidopsis thaliana (Davies and Harris, 2003). These studies showed that the microfibrils were 4-6 nm in diameter, and reduced to 3.2 nm (A. thaliana) when extracted to remove some of the non-cellulosic polysaccharides. 

Electrolyte leakage. Tissue discs, prepared from potato tubers as described above, were incubated for 16 h at 25°C between wet filter papers. After incubation, the discs were shaken in 20 ml H2O for another 60 min. One ml of this extract was diluted 30-fold with water, and subjected to conductivity measurements using a HI 8788 apparatus (Hanna Instruments). An increase in conductivity indicates a leakage of electrolytes through lesions in the cell wall caused by enzyme action. Control samples were not incubated, they were shaken in water only. 

The hydroxy-L-proline of the crude, mung-bean-wall preparation is not associated with the lectin259 this indicates a difference between the mung-bean-wall lectin and the lectin isolated from potato tubers. The latter is rich in hydroxy-L-proline, arabinose, and galactose260 in this respect, it shows features similar to those of the hydroxy-L-proline-rich glycoprotein ( extensin ) of the primary cell-wall, first reported by Lamport261 (see Section VII, 1). 

Fig. 1. Scheme for preparation of cell wall material from fresh potatoes. 

With the view of elucidating the cellulolytic component responsible for the degradation of plant cell wall, Imai and Kuroda (16) investigated the breakdown of cell walls of unicellular potato with T. viride cellulase. Potato unicells prepared with Rhizopus CSE were incubated with the fraction containing filter paper degrading cellulase and CMCase, which was obtained from T. viride cellulase preparation by using a cellulose column akin to the author s gauze column method. 

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