共查询到20条相似文献,搜索用时 31 毫秒
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In Vitis vinifera L. berries, the onset of ripening (known as “veraison”) involves loss of turgor (P) in the mesocarp cells. We hypothesized
that P loss was associated with an accumulation of apoplastic solutes in mesocarp tissue prior to veraison. Apoplastic sap
was extracted from the mesocarp by centrifugation at the appropriate gravity to measure the apoplast solute potential (ΨsA) and assay the sap composition. The ΨsA was about −0.2 MPa early in development, decreased about 1.0 MPa by veraison, and continued to decrease during ripening to
almost −4.0 MPa by the end of berry development. Potassium, malate, tartrate, proline, glucose, fructose, and sucrose were
quantified in apoplastic sap. The calculated contribution of these solutes was about 50% of the total ΨsA preveraison, but increased to about 75% as fructose and glucose accumulated during ripening. The contribution of the estimated
matric potential to apoplast water potential decreased during development and was only 1.5% postveraison. We conclude that
high concentrations of solutes accumulated in the mesocarp apoplast prior to veraison, and that P loss was a direct result
of decreased ΨsA. Because ΨsA decreased before veraison, our findings suggest that apoplast solutes play an important role in the events of cellular metabolism
that lead to the onset of ripening. 相似文献
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Papaya ( Carica papaya L. cv. Eksotika) fruit softens differentially in relation to position of the tissue. The inner mesocarp tissue is softer, and its firmness decreases more rapidly during ripening than that of the outer mesocarp tissue. As the fruit ripens, pectin solubility and depolymerisation increase. Hemicellulose, too, appears to be depolymerised but, unlike pectins, this apparent degradation of hemicellulose is associated with an increase rather than a decrease in its level. Pectin and hemicellulose depolymerisation began in the inner mesocarp tissue at about the same time as β-galactosidase (EC 3.2,1.23) activity started to increase and tissue firmness began to decrease more rapidly. In contrast, pectin solubilisation in both outer and inner mesocarp tissues occurred steadily throughout ripening at a comparable rate and paralleled closely the increase of polygalacturonase (PG; EC 3.2.1.67) and pectinesterase (EC 3.1.1.11). In general, irrespective of enzyme distribution, tissue softening during ripening was more closely related to changes in β-galactosidase activity than to PG or pectinesterase activity. Papaya, β-galactosidase appears to be an important wall degrading enzyme and may contribute significantly to differential softening, perhaps by complementing the action of polygalacturonase. Polygalacturonase activity increased with increasing depth of the mesocarp tissue, as did softening of the fruit. 相似文献
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Sakimin S. Zaharah Zora Singh Gregory M. Symons James B. Reid 《Journal of Plant Growth Regulation》2012,31(3):363-372
Rapid ripening of mango fruit limits its distribution to distant markets. To better understand and perhaps manipulate this process, we investigated the role of plant hormones in modulating climacteric ripening of ??Kensington Pride?? mango fruits. Changes in endogenous levels of brassinosteroids (BRs), abscisic acid (ABA), indole-3-acetic acid (IAA), and ethylene and the respiration rate, pulp firmness, and skin color were determined at 2-day intervals during an 8-day ripening period at ambient temperature (21?±?1°C). We also investigated the effects of exogenously applied epibrassinolide (Epi-BL), (+)-cis, trans-abscisic acid (ABA), and an inhibitor of ABA biosynthesis, nordihydroguaiaretic acid (NDGA), on fruit-ripening parameters such as respiration, ethylene production, fruit softening, and color. Climacteric ethylene production and the respiration peak occurred on the fourth day of ripening. Castasterone and brassinolide were present in only trace amounts in fruit pulp throughout the ripening period. However, the exogenous application of Epi-BL (45 and 60?ng?g?1 FW) advanced the onset of the climacteric peaks of ethylene production and respiration rate by 2 and 1?day, respectively, and accelerated fruit color development and softening during the fruit-ripening period. The endogenous level of ABA rose during the climacteric rise stage on the second day of ripening and peaked on the fourth day of ripening. Exogenous ABA promoted fruit color development and softening during ripening compared with the control and the trend was reversed in NDGA-treated fruit. The endogenous IAA level in the fruit pulp was higher during the preclimacteric minimum stage and declined during the climacteric and postclimacteric stages. We speculate that higher levels of endogenous IAA in fruit pulp during the preclimacteric stage and the accumulation of ABA prior to the climacteric stage might switch on ethylene production that triggers fruit ripening. Whilst exogenous Epi-BL promoted fruit ripening, endogenous measurements suggest that changes in BRs levels are unlikely to modulate mango fruit ripening. 相似文献
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SEXTON ROY; PALMER JANE M.; WHYTE NICHOLA A.; LITTLEJOHNS SUSAN 《Annals of botany》1997,80(3):371-376
The ripening of raspberry fruit (Rubus ideausL. cv Glen Clova)is associated with a climacteric rise in ethylene production.As the fruit pigments change from green to red there is a progressivesoftening, loss of skin strength and a breakdown of cell wallsin the mesocarp. An increase in cellulase (endo-1,4-ß-D-glucanase)in both drupelets and receptacles accompanies these changes.The localization of cellulase in the regions of the fruit associatedwith abscission zones suggest the enzyme may be involved infruit separation as well as softening. Rubus idaeusL; raspberry; fruit ripening; ethylene; abscission; cell wall breakdown; cellulase; endo-1,4-ß-D-glucanase 相似文献
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Lei Zeng Zeng Wang Alexander Vainstein Shangwu Chen Huiqin Ma 《Journal of Plant Growth Regulation》2011,30(2):199-212
Tonoplast sugar transporters are important for sugar partitioning, immobilization, and accumulation during fruit development
and ripening. Here we report the cloning, localization, and functional analysis of one of these transporters in grape berries
(Vitis vinifera L.). This clone, named VvTMT1, encodes a 742-aa protein with a calculated molecular mass of 80.2 kDa. Predicted membrane topology and phylogenetic analysis
suggest that VvTMT1 belongs to the major facilitator superfamily of membrane carriers. Semiquantitative RT-PCR suggests that VvTMT1 is a sink-specific transporter, whose expression decreases with berry development. Heterologous expression of VvTMT1 in yeast can partially restore growth of the hxt-null strain in glucose and other monosaccharide media, indicating that VvTMT1 is a functional monosaccharide transporter.
Induction of VvTMT1-GFP fusion protein expression in transgenic yeast revealed its tonoplast localization. The subcellular
localization of VvTMT1 in plants was shown by immunogold labeling of grape berry mesocarp cells and VvTMT1-GFP transient expression
in tobacco epidermis cells. Based on the above analyses of VvTMT1, this is the first report of a functional tonoplast-localized
monosaccharide transporter in grapevine. 相似文献
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Dynamic characteristics of sugar accumulation and related enzyme activities in sweet and non-sweet watermelon fruits 总被引:1,自引:0,他引:1
Jingan Liu Shaogui Guo Hongju He Haiying Zhang Guoyi Gong Yi Ren Yong Xu 《Acta Physiologiae Plantarum》2013,35(11):3213-3222
Sugar content largely determines watermelon fruit quality. We compared changes in sugar accumulation and activities of carbohydrate enzymes in the flesh (central portion) and mesocarp of elite sweet watermelon line 97103 (Citrullus lanatus subsp. vulgaris) and exotic non-sweet line PI296341-FR (C. lanatus subsp. lanatus) to elucidate the physiological and biochemical mechanisms of sugar accumulation in watermelon fruit. The major translocated sugars, raffinose and stachyose, were more unloaded into sweet watermelon fruit than non-sweet fruit. During the fruit development, acid α-galactosidase activity was much higher in flesh of 97103 than in mesocarp of 97103, in flesh and mesocarp of PI296341-FR fruit. Insoluble acid invertase activity was higher in 97103 flesh than in 97103 mesocarp, PI296341-FR flesh or mesocarp from 18 days after pollination (DAP) to 34 DAP. Changes in soluble acid invertase activity in 97103 flesh were similar to those in PI296341-FR flesh and mesocarp from 18 DAP to full ripening. Sucrose synthase and sucrose phosphate synthase activities in 97103 flesh were significantly higher than those in 97103 mesocarp and PI296341-FR fruits from 18 to 34 DAP. Only insoluble acid invertase and sucrose phosphate synthase activities were significantly positively correlated with sucrose content in 97103 flesh. Therefore, phloem loading, distribution and metabolism of major translocated sugars, which are controlled by key sugar metabolism enzymes, determine fruit sugar accumulation in sweet and non-sweet watermelon and reflect the distribution diversity of translocated sugars between subspecies. 相似文献
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Kylie J. Nunan Ian M. Sims Antony Bacic Simon P. Robinson Geoffrey B. Fincher 《Plant physiology》1998,118(3):783-792
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. 相似文献