A xyloglucan from persimmon fruit cell walls
Persimmon (Diospyros kaki L.) fruit cell walls have been shown to contain a high proportion of xyloglucan. This hemicellulosic polysaccharide appears to play a crucial role in the softening process that accompanies fruit ripening. In the present work, xyloglucan from persimmon fruit cell walls was extracted, purified and chemically characterized from alkali-extracted hemicelluloses. Monosaccharide analysis of purified xyloglucan showed a molar ratio of Glc:Xyl:Gal:Fuc of 10.0:6.0:3.4:1.4. Linkage analysis showed a high proportion of terminal residues, indicating a low degree of polymerization of side-chains.
Xyloglucan endotransglucosylase and cell wall extensibility
Transgenic tomato hypocotyls with altered levels of an XTH gene were used to study how XET activity could affect the hypocotyl growth and cell wall extensibility. Transgenic hypocotyls showed significant over-expression (line 13) or co-suppression (line 33) of the SlXTH1 in comparison with the wild type, with these results being correlated with the results on specific soluble XET activity, suggesting that SlXTH1 translates mainly for a soluble XET isoenzyme. A relationship between XET activity and cell wall extensibility was found, and the highest total extensibility was located in the apical hypocotyl segment of the over-expressing SlXTH1 line, where the XET-specific activity and hypocotyl…