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Cutillas-Iturralde A; Fulton D; Fry S; Lorences E 《Journal of experimental botany》1998,49(321):701-706
In this work the effect of injection of xyloglucan-derived oligosaccharides
(XGOs) into whole persimmon (Diospyros khaki L.)
fruits on ethylene biosynthesis was investigated. Fruits collected during
different ripening stages produced low levels of ethylene without a
climacteric-like peak. Pretreatment of these fruits with 10
cm3 C2H4 m-3 for 8 h
stimulated little or no endogenous ethylene production. However, when
persimmon fruits were injected with a mixture of XGOs a burst in ethylene
production was observed compared with water-injected control fruits or
fruits injected with different monosaccharide solutions. In order to study
the influence of oligosaccharide structure and fruit ripening stage on the
ability of XGOs to induce ethylene synthesis, fucosylated and
non-fucosylated XGOs were injected into persimmon fruits harvested at two
different ripening stages. Both oligosaccharide structures were able to
induce ethylene production. Induction of ethylene by XGOs was much more
evident in fruits harvested later in time, indicating that the process is
developmentally regulated. The levels of 1-aminocyclopropane-1-carboxylic
acid (ACC) in injected persimmon fruits were also examined. This study
showed that the increase in the rate of ethylene biosynthesis induced by
XGOs was accompanied by the accumulation of its metabolic precursor
ACC. 相似文献
2.
Effect of Xyloglucan Oligosaccharides on Growth,Viscoelastic Properties,and Long-Term Extension of Pea Shoots 总被引:2,自引:0,他引:2
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The growth-promoting effect of xyloglucan-derived oligosaccharides was investigated using a bioassay with entire pea (Pisum sativum L., var Alaska) shoots. After a 24-h incubation period at 25[deg]C, xyloglucan oligosaccharide (XGO) solutions with concentrations of 10-6 M notably increased the growth rate of pea shoots, whereas the same oligosaccharides at 10-7 M were less effective. To investigate the possible correlation between growth rate changes in the XGO-treated shoots and changes in the wall mechanical properties of their growing regions (third internodes), we used a short-term creep assay. The promotion of elongation by XGOs was reflected in an enhancement of the viscoelasticity of the growing regions of the shoots. To show whether this effect on wall viscoelastic properties was the cause or a consequence of their growth promotion, we tested the effect of XGOs on the long-term extension of isolated cell walls. We characterized an acid-induced extension in isolated cell walls from pea shoots that was not inhibited by preincubation in neutral buffers. Exogenously added XGOs did not alter the pattern of pea segment extension at any pH tested, indicating that XGOs have no direct effect on cell wall viscoelasticity. Finally, preincubation of pea segments in neutral buffers with XGOs enhanced their capacity to extend under acidic conditions. This finding suggests that XGOs at a neutral pH can act via transglycosylation, weakening the wall matrix and making the wall more responsive to other mechanisms of acid-induced extension as an expansin-mediated extension. 相似文献
3.
Antonio Cutillas-Iturralde Ignacio Zarra Ester P. Lorences 《Physiologia plantarum》1993,89(2):369-375
Pectins from persimmon ( Diospyros kaki L.) fruit pericarp were sequentially extracted with 0. 05 M trans -1,2-diaminocyclohexane-N,N, N', N'-tetraacetic acid (CDTA), 0. 05 M Na2 CO3 (1°C) and Na2 CO3 (20°C) and the carbohydrate composition and metabolism during development determined. Young persimmon fruits contained a large proportion of pectins, 46% by dry weight, that decreased to 20% with ripening. This decrease occurred in the CDTA and Na2 CO3 (1°C) fractions, mainly composed of uronic acids, and represents a net loss of uronic acids, arabinose and galactose. The amount of non-cellulosic neutral sugars was especially high in the Na2 CO3 (20°C) fraction. The loss of pectins was also accompanied by a depolymerisation of the polysaccharides extracted in the three pectic fractions. However, none of these changes can be attributed to the action of polygalacturonase activity. Proteins were extracted from the pericarp tissue, but endopolygalacturonase (EC 3. 2. 1. 15) activity, determined as a decrease in viscosity of polygalacturonic acid, was not observed in the extract. Determination of exopolygalacturonase (EC 3. 2. 1. 67) activity by measuring the release of reducing groups from polygalacturonic acid was also negative. The results presented indicate that polygalacturonase is not responsible for the metabolism of pectins during persimmon fruit ripening. 相似文献
4.
Implication of persimmon fruit hemicellulose metabolism in the softening process. Importance of xyloglucan endotransglycosylase 总被引:4,自引:0,他引:4
Antonio Cutillas-Iturralde Ignacio Zarra Stephen C. Fry Ester P. Lorences 《Physiologia plantarum》1994,91(2):169-176
Hemicellulosic polysaccharides from persimmon fruit ( Diospyros kaki L.) pericarp were extracted from depectinated cell walls with 0.5, 1 and 4 M KOH at different stages of development: (I) maximal growth corresponding to the first sigmoidal growth phase; (II) cessation of growth corresponding to the lag between the first and the second sigmoidal phases; (III) maximal growth corresponding to the second sigmoidal phase; and (IV) cessation of growth when the fruit had reached its maximum size and the change in colour (green to red) had taken place. During fruit development the amount of total hemicelluloses per unit dry mass cell wall decreased twofold. Xyloglucan was present in the three hemicellulosic fractions, and also decreased with fruit age, although its amount relative to other hemicelluloses increased. The amount of xyloglucan was especially high in the hemicelluloses extracted with 4 M KOH, representing more than 50% at stages III and IV. The average molecular mass of xyloglucan increased from stage I through stage II (0.5 M hemicellulosic fraction) or through stage III (I and 4 M hemicellulosic fractions) and decreased after that. The xyloglucan endotransglycosylase (XET: EC 2.4.1.-) activity was measured as the incorporation of [3 H]XXXGol (reduced xyloglucan heptasaccharide labelled at position 1 of the glucitol moiety) into partially purified persimmon fruit xyloglucan. XET specific activity increased greatly between stages I and II. The importance of this enzyme during fruit ripening is discussed. 相似文献
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