The cell wall differences between crisp and soft cherry fruits are reported. The penetrometric measurements are correlated with the physiological stage of fruits but not with the sensory analysis at maturity. The major difference lies in the degree of polymerization of pectin side chains. A high degree of polymerization produces a rigid cell wall with numerous bonds between the polymers of crisp fruits:  the cells present regular forms. On the contrary, the soft fruits possess fewer interactions between polymers, and consequently, the cells present irregular forms. Keywords: Cherry; pectin; softening; turnover

In Capsicum annuum leaves, some phenolic compounds, such as chlorogenic acid and various apigenin or luteolin glycosides, can be separated by HPLC technique. During infection with Phytophthora capsici (the agent of pepper mildew), the concentrations of these compounds decreased. A fungal glucosidasic activity may be implicated, producing apigenin aglycon in the necrotic areas. Some of the phenolic compounds were only present in intercellular spaces, where their concentration increased during fungal infection, mostly in ihe resistant pepper cultivar.The Involvement of phenolics in C. annuum resistance is discussed in relation to oxidative metabolism. Zusaramenfassung Verhalten der phenolischen Verbidiingen in mit Phytophlhora capsici infizierten Capsicum aJuiuvrn-BIMernDurch die HPLC-Technik lassen sich einige in Blattem von Paprika (Capsicum annuum) enthaltene phenohsche Verhindungen trennen, wie Chlorogensaure und verschiedene Apigenin-bzw. LuteolingWkoside, Wahrend der Infektion mit Phytophthora capsici (dem Erreger des PapHkamehltaus) gingen die Konzentrationen dieser Verbindungen zurUck. Eine Glukosidaseaktivitat des Pilzes konnte zur Bildung von Apigenin-Aglykon in den nekrotischen Flachen fuhren, Einige der phenolischen Verbindungen kamen nur in den Interzellularraumen vor, wo ihre Konzentration vor allem hei der resistenten Paprikasorte wahrend der Pilzinfektion zunahm.Die Beteiligung phenolischer Verbindungen an der Resistenz von C. annuum wird unter Bezug auf den oxidativen Metabolismus diskutiert.

The chromatographic analysis of the free carbohydrate content of leaves and stems of pepper showed 19 major fractions which were gathered in 8 structural classes. A number of correlations were found between the respective carbohydrate levels of two varieties of pepper, one susceptible and the other resistant to downy mildew, and also between those of healthy and inoculated tissues. Some cases of departures from the established correlations were observed and discussed with respect to their hypothetical involvement in the character of resistance and susceptibility to the infection. The concentrations of free carbohydrates of the dideoxyhexose group are increased in inoculated leaves of both susceptible and resistant varieties and those of the rhamnose group are depressed in inoculated leaves of the sole susceptible variety. Sucrose strongly increases in inoculated stems but decreases in the inoculated leaves of the sole resistant variety; concomitantly glucose and fructose also increase in inoculated stems, whereas they decrease in inoculated leaves of both susceptible and resistant strains. The results suggest a number of hypotheses concerning the molecular mechanisms of the host resistance to infection in relation to the cellular pathways of sugar translocation.

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.

This study presents a comparison between tissues of treated and nontreated Bigarreau-Napoléon cherries using physiochemical and cytological tests. Ethephon provokes a cell wall destructuration greater in the mesocarp tissue than in the under-peduncular area. It consists of breakage or an enlargement of some cell walls with the formation of a hydrated pectin network. Ethephon induces a cell wall catabolism characteristic of a fast cell wall senescence.Key words: Ethephon, ethylene, Bigarreau-Napoléon cherries, cell wall alterations, mechanical harvest.