Ultrastructure des parois de cerises Bigarreau Burlat de textures différentes au cours de la maturation

Abstract

The changes in texture of fruits during ripening are linked to cell wall degradation involving synthesis and degradation of polymers. An increase in pectin solubility leads to cell sliding and an elastic aspect of tissues. The biochemical cell wall process differs between soft and crisp fruits originating from a same cultivar but cultivated under different agroclimatic conditions. Although the proportions of cell wall material are similar, the composition and structure of the two cell walls are very different at maturity. A solubilization of the middle lamella and a restructuration of the primary cell walls arising from the cells separation is observed in crisp fruits. In contrast, the middle lamella of the soft fruits is better preserved and the primary cell walls are thin and show degradation bags delimited by residual membrane formations. In addition, the macroendocytosis process by endosome individualization is more important in soft fruits. In conclusion, the fruit texture depends on the extent of the links between cell wall polymers. Keywords: cherry, cell wall, texture, ultrastructural study.

Developmental changes in cell wall polysaccharides from sweet cherry (Prunus avium L.) cultivars with contrasting firmness

“…However, in other cases, softening occurred without extensive endo-polygalacturonase action and pectin dismantling (Batisse et al, 1994). Polyuronides became more soluble (Fils-Lycaon and Buret, 1990;Batisse et al, 1996b), rhamnogalacturonan I (RG-I) side chains were removed (Kondo and Danjo, 2001) and some cell wall-degrading enzymes such as pectin methyl esterase, polygalacturonase, and ␤-galactosidase increased as the cherry ripened (Fils-Lycaon and Buret, 1990;Barrett and Gonzalez, 1994;Andrews and Shulin, 1995). However, the specific contribution of each of these changes to the softening process is still far from being understood.…”

Lanosidade em cultivares de pêssego (Prunus persica (L.) Batsch): estudos anatômicos e ultra-estruturais

“…tais substâncias. Batisse et al (1996) descrevem um processo similar em frutos de cereja durante o amadurecimento e o denominam de macroendocitose. A diferença entre os dois processos está no fato de que, em pêssegos 'Dourado-2', não se observa a formação de 'vesículas' no espaço parietal como os autores ilustram em cereja.…”

“…A diferença entre os dois processos está no fato de que, em pêssegos 'Dourado-2', não se observa a formação de 'vesículas' no espaço parietal como os autores ilustram em cereja. Porém, nos frutos estudados, a presença de vesículas (endossomos) de diferentes tamanhos no citoplasma e no vacúolo, contendo substância parietal, pode estar relacionada à eliminação dos produtos residuais originários da modificação parietal, como sugerido por Batisse et al (1996) em frutos de cereja. A presença de endossomos, contendo material parietal no interior de vacúolos, sugere que esteja ocorrendo um processo de reabsorção destes materiais, levando à superação da lanosidade quando os frutos de pêssegos 'Dourado 2' são transferidos para temperaturas mais elevadas.…”

Influence of water soluble coatings on posharvest quality of sweet cherry (Prunes avium L.) grown in Gilgit-Baltistan

“…In sweet cherries the softness depend on the increase activities of enzymes responsible for fruit quality loss i.e. poly galacturonase, ß-galactosidase and pectin methyl esterase (Batisse et al, 1996;Gerardi et al, 2001;Remon et al, 2003). These findings agree the studies of Yaman and Bayindirh (2002) that coated the sweet cherry with semperfresh having different concentrations and reported that it help in slowing down the rate of decrease in firmness values with the increase in semperfresh concentrations.…”