Changes in Cell Wall Composition during Ripening of Grape Berries

Abstract

Cell walls were isolated from the mesocarp of grape (Vitis vinifera L.) berries at developmental stages from before veraison through to the final ripe berry. Fluorescence and light microscopy of intact berries revealed no measurable change in cell wall thickness as the mesocarp cells expanded in the ripening fruit. Isolated walls were analyzed for their protein contents and amino acid compositions, and for changes in the composition and solubility of constituent polysaccharides during development. Increases in protein content after veraison were accompanied by an approximate 3-fold increase in hydroxyproline content. The type I arabinogalactan content of the pectic polysaccharides decreased from approximately 20 mol % of total wall polysaccharides to about 4 mol % of wall polysaccharides during berry development. Galacturonan content increased from 26 to 41 mol % of wall polysaccharides, and the galacturonan appeared to become more soluble as ripening progressed. After an initial decrease in the degree of esterification of pectic polysaccharides, no further changes were observed nor were there large variations in cellulose (30-35 mol % of wall polysaccharides) or xyloglucan (approximately 10 mol % of wall polysaccharides) contents. Overall, the results indicate that no major changes in cell wall polysaccharide composition occurred during softening of ripening grape berries, but that significant modification of specific polysaccharide components were observed, together with large changes in protein composition.

Shelf-life enhancement of papaya with aloe vera gel coating at ambient temperature

“…Coated papaya retarded TSS development because aloe gel decreases the respiration and eventually matabolism of sugars. This may be due to the effect of aloe vera gel coating on the reduction of α-galactosidase, polygalacturonase and pectinmethylesterase activities (Nunan et al 1998).…”

Integrative Effects of Vine Water Relations and Grape Ripeness Level of Vitis vinifera L. cv. Shiraz/Richter 99. II. Grape Composition and Wine Quality

“…1), extraction may still have increased because of the simultaneous effect of the reduction in berry volume (and concomitant increase in skin:pulp ratio) during this time (Hunter et al, 2014) as well as the softening of the berries as ripening proceeded. A loss in cellular integrity during the softening and shrinking process (a change in cell wall polysaccharides, possibly brought about by cell wall enzymes such as, amongst others, endo-and exo-hydrolases and endo-polygalacturonase - Dreier et al, 1998;Nunan et al, 1998) may have occurred. This is also in line with the reduction in sucrose contents and the possible involvement of the sucrose-hydrolysing invertase enzymes in the skin during this time (Ruffner et al, 1990;Zhang et al, 2006;Hunter et al, 2014).…”

Grapes on Steroids. Brassinosteroids Are Involved in Grape Berry Ripening

“…Grape berry ripening is the result of the combination of a number of processes, such as berry expansion and softening, sugar and color accumulation, and flavor and aroma development. Much of the increase in berry size and weight after véraison is caused by an accumulation of water and sugar and an increase in cell expansion, facilitated by significant cell wall modification (Nunan et al, 1998). Expression patterns of genes encoding cell wall-modifying enzymes during grape berry development show increases in the expression of VvXET genes, which encode xyloglucan endotransglycosylases (XETs), post véraison (Nunan et al, 2001).…”