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1.
Molecules ; 26(17)2021 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-34500562

RESUMO

Gluconeogenesis is a key interface between organic acid/amino acid/lipid and sugar metabolism. The aims of this article are four-fold. First, to provide a concise overview of plant gluconeogenesis. Second, to emphasise the widespread occurrence of gluconeogenesis and its utilisation in diverse processes. Third, to stress the importance of the vacuolar storage and release of Krebs cycle acids/nitrogenous compounds, and of the role of gluconeogenesis and malic enzyme in this process. Fourth, to outline the contribution of fine control of enzyme activity to the coordinate-regulation of gluconeogenesis and malate metabolism, and the importance of cytosolic pH in this.


Assuntos
Aminoácidos/metabolismo , Gluconeogênese/fisiologia , Lipídeos/fisiologia , Plantas/metabolismo , Açúcares/metabolismo , Ciclo do Ácido Cítrico/fisiologia , Malato Desidrogenase/metabolismo , Nitrogênio/metabolismo
2.
Int J Mol Sci ; 22(15)2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34360556

RESUMO

In grapevines, as in other plants, sucrose and its constituents glucose and fructose are fundamentally important and carry out a multitude of roles. The aims of this review are three-fold. First, to provide a summary of the metabolism and transport of sucrose in grapevines, together with new insights and interpretations. Second, to stress the importance of considering the compartmentation of metabolism. Third, to outline the key role of acid invertase in osmoregulation associated with sucrose metabolism and transport in plants.


Assuntos
Metabolismo dos Carboidratos , Frutas/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Sacarose/metabolismo , Vitis/metabolismo , Frutas/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Vitis/crescimento & desenvolvimento
3.
Front Plant Sci ; 11: 573982, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33281843

RESUMO

The partitioning of assimilates in fruits, which are economically important sink organs, is ruled by different physiological processes and affected by both environmental and agronomical factors. The bulk of the water and solutes, required for growth, is imported into fruits and seeds through xylem and phloem. In the stone fruits, five vascular bundles enter the base of the fruit, then dividing to supply either the flesh or the seed. The main sugars accumulated in stone fruits include fructose, glucose, and sucrose, along with other minor saccharides. The mechanisms of phloem loading in these fruit species have not been fully elucidated yet, but the available data hint either an apoplastic or a symplastic type or possibly a combination of both, depending on the species and the sugar considered. Similarly, phloem unloading mechanisms, elucidated for a small number of species, depend on genotype and developmental stage. Remarkably, key enzymes and transporters involved in the main sugars-conversion and transport pathways have received considerable attention. In stone fruit trees, the presence of an elevated number of fruits alters the source-sink balance, with a consequent intensification of competition among them and between vegetative and reproductive growth. The main environmental factors affecting this balance and the agronomical/artificial manipulations of source-sink relationships to achieve adequate fruit production and quality are reviewed.

4.
Front Plant Sci ; 11: 549921, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33240291

RESUMO

Non-structural carbohydrates are abundant constituents of the ripe flesh of all stone fruits. The bulk of their content comprises sucrose, glucose, fructose and sorbitol. However, the abundance of each of these carbohydrates in the flesh differs between species, and also with its stage of development. In this article the import, subcellular compartmentation, contents, metabolism and functions of non-structural carbohydrates in the flesh of commercially cultivated stone fruits of the family Rosaceae are reviewed.

5.
Front Plant Sci ; 11: 572601, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33101339

RESUMO

Stone fruits of the Rosaceae family consist of several distinct parts, and these include the flesh, woody endocarp, and seed. To understand the metabolism of these fruits, it is necessary to have knowledge of both their structure and growth characteristics. The nitrogen metabolism of the different tissues of stone fruits is interlinked. For example, there is an import and storage of nitrogenous compounds in the endocarp that are then exported to the seed. Moreover, there are links between the metabolism of nitrogen and that of malic/citric acids. In this article, the structure and growth characteristics, together with the import/export, contents, metabolism, and functions of nitrogenous compounds and organic acids in the different parts of stone fruits and their seeds are reviewed.

6.
Front Plant Sci ; 11: 562252, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32983215

RESUMO

Phytochemicals or secondary metabolites present in fruit are key components contributing to sensory attributes like aroma, taste, and color. In addition, these compounds improve human nutrition and health. Stone fruits are an important source of an array of secondary metabolites that may reduce the risk of different diseases. The first part of this review is dedicated to the description of the main secondary organic compounds found in plants which include (a) phenolic compounds, (b) terpenoids/isoprenoids, and (c) nitrogen or sulfur containing compounds, and their principal biosynthetic pathways and their regulation in stone fruit. Then, the type and levels of bioactive compounds in different stone fruits of the Rosaceae family such as peach (Prunus persica), plum (P. domestica, P. salicina and P. cerasifera), sweet cherries (P. avium), almond kernels (P. dulcis, syn. P. amygdalus), and apricot (P. armeniaca) are presented. The last part of this review encompasses pre- and postharvest treatments affecting the phytochemical composition in stone fruit. Appropriate management of these factors during pre- and postharvest handling, along with further characterization of phytochemicals and the regulation of their synthesis in different cultivars, could help to increase the levels of these compounds, leading to the future improvement of stone fruit not only to enhance organoleptic characteristics but also to benefit human health.

7.
Front Plant Sci ; 11: 1054, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32733527

RESUMO

Cell wall turnover and modification in its composition are key factors during stone fruit development and patterning. Changes in cell wall disassembly and reassembly are essential for fruit growth and ripening. Modifications in cell wall composition, resulting in the formation of secondary cell walls, are necessary for producing the most distinctive trait of drupes: the lignified endocarp. The contribution of primary metabolism to cell wall synthesis has been investigated in detail, while the knowledge on the contribution of the cell wall to primary metabolites and related processes is still fragmented. In this review, starting from peculiarities of cell wall of drupes cells (in mesocarp and endocarp layers), we discuss the structure and composition of cell wall, processes related to its modification and contribution to the synthesis of primary metabolites. In particular, our attention has been focused on the ascorbate synthesis cell wall-related and on the potential role of cyanogenic compounds in the deposition of the secondary cell wall.

8.
Foods ; 8(10)2019 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-31614805

RESUMO

The characteristics of plum fruits of three different species were investigated throughout their development (including over-ripening). The content of primary and secondary metabolites was expressed as amount per gram DW (dry weight) and per fruit in order to obtain information about the balance between their synthesis and dissimilation at different stages of fruit development. In all the plums, during the first stages of development, glucose was the most abundant sugar, whereas sucrose increased during ripening. There was no decrease in malate content per fruit before the commercial harvesting time of any of the plums, whereas a decrease was observed during over-ripening. In general, both the total phenol content and the contents of individual phenols in the flesh expressed on gram DW decreased throughout development, whereas their content per fruit increased, indicating that these decreases were due to a dilution effect arising from the expansion of the flesh. During the development of the flesh, the increase in the contents of the investigated metabolites per fruit shows that there was no net dissimilation of malate up to commercial harvest and of phenols throughout fruit development. Good correlations between the content of phenols to antioxidant activity were found. Shiro flesh, during the last part of fruit development, had lower total carbohydrate and polyphenol contents, lower antioxidant activities, and a higher malate content than the flesh of the other two genotypes.

9.
Plant Physiol Biochem ; 130: 324-333, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30041084

RESUMO

Two pathways can be used by gluconeogenesis in plants: one employs phosphoenolpyruvate carboxykinase (PEPCK) and the other pyruvate orthophosphate dikinase (PPDK). The occurrence-location of these enzymes was determined in developing kernels of maize. PPDK was much more abundant than PEPCK in extracts of whole kernels. However, their location within the kernel was different. PPDK was particularly abundant in the peripheral endosperm (in which alanine is abundant), whereas PEPCK was localised in the pedicel and basal endosperm transfer cells (where asparagine is metabolised). The abundance of these enzymes was also determined in maize roots where there was a massive increase in abundance of PEPCK and a small increase in abundance of PPDK when they were fed ammonium; PEPCK was located in the pericycle and various cell types associated with the vasculature. On the other hand, there was a large increase in abundance of PPDK in roots subjected to anoxia (which induces an accumulation of alanine), whereas the abundance of PEPCK was decreased. These results show: firstly, that gluconeogenesis can potentially occur in many different tissues of maize. Secondly, within one organ PPDK can be abundant in some tissues and PEPCK in others. Thirdly, the abundance of PPDK and PEPCK is often associated with the metabolism of certain nitrogenous compounds and can be dramatically altered by factors related to nitrogen metabolism. In maize roots and developing kernels PPDK was associated with alanine metabolism. By contrast, the presence of PEPCK in maize roots and kernels was associated with either ammonium or asparagine metabolism. We propose that gluconeogenesis is often a component of a widespread mechanism that is used in coordinating the import/mobilisation of nitrogenous compounds with their utilisation. Further, potentially component of this mechanism may have provided building blocks that were used in the evolution of processes such as C4 photosynthesis, Crassulacean acid metabolism, stomatal metabolism and the biochemical pH stat.


Assuntos
Gluconeogênese , Nitrogênio/metabolismo , Zea mays/metabolismo , Grão Comestível/metabolismo , Eletroforese em Gel de Poliacrilamida , Immunoblotting , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Raízes de Plantas/metabolismo , Piruvato Ortofosfato Diquinase/metabolismo
10.
Plant Physiol Biochem ; 118: 618-626, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28802240

RESUMO

The effect of late summer - autumn limitation of phloem export on growth, photosynthesis and storage carbohydrate accumulation, was evaluated in walnut (Juglans regia L.). This was done by girdling current years shoots, with either all or with only a third of the leaves left in place. Nineteen days after girdling, photosynthesis was greatly reduced and after 46 days, it was about 70% lower in both girdling treatments compared to the control (ungirdled shoots). This reduction is consistent with a feed-back effect of an increased carbohydrate content of the leaves. At the end of the experiment (46 days after girdling), the radial growth of girdled shoots was increased at their base but not at their apical part compared to the control. Girdling increased the accumulation of sucrose in the bark at the base of the shoot and of starch in the bark and in the wood of the shoot apical part. The activity of ADP-glucose pyrophosphorylase in wood increased in the apical part of girdled shoots. The results suggest that a high availability of carbohydrates elicits a feed-forward action on the shoot sink size and activity (radial growth and storage carbohydrate accumulation). Further, for the first time in tree wood we found an increased total activity of AGP induced by an increased assimilate availability. Moreover, the results indicated that, in late summer - autumn, CO2 uptake by leaves of the deciduous tree walnut is strongly dependent on export of photosynthates from the crown. Therefore, carbon uptake in this period depends largely on the availability of effective storage sinks where newly produced assimilates can be accumulated.


Assuntos
Metabolismo dos Carboidratos/fisiologia , Juglans/metabolismo , Fotossíntese/fisiologia , Brotos de Planta/metabolismo , Estações do Ano , Amido/biossíntese
11.
Plant Physiol Biochem ; 112: 9-18, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28012288

RESUMO

Peach leaf curl is a disease that affects the leaves of peach trees, and in severe cases all of the leaf can be similarly affected. This study investigated some effects of this disease on the metabolism of peach leaves in which all parts of the leaf were infected. These diseased leaves contained very little chlorophyll and performed little or no photosynthesis. Compared to uninfected leaves, diseased leaves possessed higher contents of fructose and especially glucose, but lowered contents of sucrose, sorbitol and especially starch. The activities of soluble acid invertase, neutral invertase, sorbitol dehydrogenase and sucrose synthase were all higher in diseased leaves, whereas, those of aldose-6-phosphate reductase and sucrose phosphate synthase were lower. The activities of hexokinase and fructokinase were little changed. In addition, immunblots showed that the contents of Rubisco and ADP-glucose phosphorylase were reduced in diseased leaves, whereas, the content of phosphoenolpyruvate carboxylase was increased. The results show that certain aspects of the metabolism of diseased leaves are similar to immature sink leaves. That is photosynthetic function is reduced, the leaf imports rather than exports sugars, and the contents of non-structural carbohydrates and enzymes involved in their metabolism are similar to sink leaves. Further, the effects of peach leaf curl on the metabolism of peach leaves are comparable to the effects of some other diseases on the metabolism of photosynthetic organs of other plant species.


Assuntos
Metabolismo dos Carboidratos , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Prunus persica/metabolismo , Prunus persica/microbiologia , Carboidratos/análise , Fotossíntese , Folhas de Planta/enzimologia , Proteínas de Plantas/metabolismo , Prunus persica/enzimologia
12.
Plant Physiol Biochem ; 108: 323-327, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27497301

RESUMO

This study determined whether phosphoenolpyruvate carboxykinase (PEPCK) and phosphoenolpyruvate carboxylase (PEPC) are phosphorylated in the flesh of a range of fruits. This was done by incubating fruit flesh with 32P[P] (where 32P[P] = 32PO43-), then PEPCK and PEPC were immunoprecipitated from extracts using specific antisera. The incorporation of 32P[P] into these enzymes was then determined by autoradiography of SDS-PAGE gels. Both enzymes were subject to phosphorylation in vivo in the flesh of grape, tomato, cherry and plum. PEPCK was also subject to phosphorylation in vivo in developing grape seeds. Proteolytic cleavage of PEPCK showed that it was phosphorylated at a site(s) located on its N-terminal extension. Potentially phosphorylation of these enzymes could contribute to the coordinate regulation of their activities in the flesh of fruits and in developing seeds.


Assuntos
Frutas/enzimologia , Magnoliopsida/enzimologia , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Fosfoenolpiruvato Carboxilase/metabolismo , Proteínas de Plantas/metabolismo , Cucumis sativus/enzimologia , Cucumis sativus/metabolismo , Frutas/metabolismo , Lycopersicon esculentum/enzimologia , Lycopersicon esculentum/metabolismo , Magnoliopsida/metabolismo , Radioisótopos de Fósforo/farmacocinética , Fosforilação , Prunus/enzimologia , Prunus/metabolismo , Sementes/enzimologia , Sementes/crescimento & desenvolvimento , Distribuição Tecidual , Vitis/enzimologia , Vitis/metabolismo
13.
J Plant Physiol ; 202: 34-44, 2016 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-27450492

RESUMO

In this study the occurrence of a number of enzymes involved in gluconeogenesis was investigated in both tomato fruits and leaves during their development and senescence and in some other fruits. The enzymes studied were phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK) and glyoxysomal isocitrate lyase (ICL). PPDK was detected in the ripe flesh of tomato, and much smaller amounts were detected in the flesh of both peach and pepper, whereas it was not detected (not present or at very low abundance) in the other fruits which were investigated (apricot, aubergine, blackberry, blueberry, cherry, grape, plum, raspberry and red current). By contrast PEPCK was present in the flesh of all the fruits investigated. Very small amounts of ICL were detected in ripe tomato flesh. PEPCK was present in the skin, flesh, locular gel and columella of tomato fruit, and in these its abundance increased greatly during ripening. PPDK showed a similar distribution, however, its abundance did not increase during ripening. PEPCK was not detected in tomato leaves at any stage of their development or senescence. The content of PPDK g(-1) fresh weight (FW) increased in tomato leaves as they matured, however, it declined during their senescence. In tomato leaves the content of ICL g(-1) FW increased until the mid-stage of development, then decreased as the leaf matured, and then increased during the latter stages of senescence. In the flesh of tomato fruits the contents of PPDK and PEPCK g(-1) FW decreased during senescence. The results suggest that in fruits other than tomato the bulk of any gluconeogenic flux proceeds via PEPCK, whereas in tomato both PEPCK and PPDK could potentially be utilised. Further, the results indicate that the conversion of pyruvate/acetyl-CoA to malate by the glyoxylate cycle, for which ICL is necessary, is not a major pathway utilised by gluconeogenesis in fruits under normal conditions of growth. Finally, the results contribute to our understanding of the role of several enzymes in the senescence of both leaves and fruits.


Assuntos
Frutas/enzimologia , Isocitrato Liase/metabolismo , Lycopersicon esculentum/enzimologia , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Folhas de Planta/enzimologia , Prunus persica/enzimologia , Piruvato Ortofosfato Diquinase/metabolismo , Gluconeogênese , Modelos Biológicos , Peptídeos/metabolismo
14.
Plant Physiol Biochem ; 101: 33-42, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26852108

RESUMO

The first aim of this study was to determine the contribution of stored malate and citrate to the substrate requirements of metabolism in the ripening flesh of the peach (Prunus persica L. Batsch) cultivar Adriatica. In the flesh, stored malate accumulated before ripening could contribute little or nothing to the net substrate requirements of metabolism. This was because there was synthesis and not dissimilation of malate throughout ripening. Stored citrate could potentially contribute a very small amount (about 5.8%) of the substrate required by metabolism when the whole ripening period was considered, and a maximum of about 7.5% over the latter part of ripening. The second aim of this study was to investigate why phosphoenolpyruvate carboxykinase (PEPCK) an enzyme utilised in gluconeogenesis from malate and citrate is present in peach flesh. The occurrence and localisation of enzymes utilised in the metabolism of malate, citrate and amino acids were determined in peach flesh throughout its development. Phosphoenolpyruvate carboxylase (essential for the synthesis of malate and citrate) was present in the same cells and at the same time as PEPCK and NADP-malic enzyme (both utilised in the dissimilation of malate and citrate). A hypothesis is presented to explain the presence of these enzymes and to account for the likely occurrence of gluconeogenesis.


Assuntos
Ácido Cítrico/metabolismo , Frutas/metabolismo , Gluconeogênese/fisiologia , Malatos/metabolismo , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Proteínas de Plantas/metabolismo , Prunus persica/metabolismo
15.
Plant Physiol Biochem ; 97: 62-9, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26432988

RESUMO

Glycolysis from sugars is necessary at all stages of development of grape pericarp, and this raises the question as to why gluconeogenesis from malate occurs. Phosphoenolpyruvate carboxykinase (PEPCK) is required for gluconeogenesis in grape pericarp. In this study we determined the abundance of PEPCK protein and activity in different parts of grape pericarp during its development. Both PEPCK protein and activity were present throughout development, however, in both the skin and the flesh their abundance increased greatly at the start of ripening. This coincided with the onset of the decrease in the malate content of the berry. The location of PEPCK in the pericarp at different stages of development was determined using both immunohistochemistry and dissection. We provide a possible explanation for the occurrence of gluconeogenesis in grape pericarp.


Assuntos
Gluconeogênese , Malatos/metabolismo , Fosfoenolpiruvato Carboxilase/metabolismo , Vitis/enzimologia , Frutas/metabolismo , Fosfoenolpiruvato/metabolismo , Proteínas de Plantas/metabolismo , Vacúolos/metabolismo
16.
Plant Physiol Biochem ; 84: 261-270, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25306529

RESUMO

It is uncertain whether the enzymes pyruvate orthophosphate dikinase (PPDK) or isocitrate lyase (ICL) are present in the pericarp of grape, in which they could function in gluconeogenesis. The occurrence of these and other enzymes was investigated in the pericarp of three cultivars of grape (Vitis vinifera L.). In particular, the abundance of the enzymes aldolase, glutamine synthase (GS), acid invertase, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPC), PPDK and ICL were determined during the development of the pericarp of the cultivars Cabernet Sauvignon, Chardonnay and Zibibbo. PPDK and ICL were not detected at any stage of development. Each of the other enzymes showed different changes in abundance during development. However, for a given enzyme its changes in abundance were similar in each cultivar. In the ripe pericarp of Cabernet Sauvignon, PEPC, cytosolic GS and aldolase were equally distributed between the vasculature and parenchyma cells of the flesh and skin. The absence or very low abundance of PPDK provides strong evidence that any gluconeogenesis from malate utilises phosphoenolpyruvate carboxykinase (PEPCK). The absence or very low abundance of ICL in the pericarp precludes any gluconeogenesis from ethanol.


Assuntos
Vitis/enzimologia , Vitis/metabolismo , Frutas/enzimologia , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Gluconeogênese/genética , Gluconeogênese/fisiologia , Fosfoenolpiruvato Carboxiquinase (ATP) , Fosfoenolpiruvato Carboxilase/genética , Fosfoenolpiruvato Carboxilase/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Vitis/genética
17.
Plant Physiol Biochem ; 76: 52-7, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24463535

RESUMO

A widely held view is that in grape pericarp glycolysis is inhibited during ripening, and that stored malate rather than sugars become the major substrate for respiration. In this study we determined what contribution stored malate could make to the substrate requirements of respiration and ethanolic fermentation in the pericarp of Cabernet Sauvignon berries during ripening. At a number of time points through development the amount of malate in the pericarp was measured. The change in malate content between each time point was then calculated, having first allowed for dilution arising from expansion of the fruit. The amount of CO2 that was released by the berry in the interval between each pair of time points was measured. It was found that the contribution that stored malate could make to the substrate requirements of respiration and ethanolic fermentation of grape pericarp was dependent on the stage of ripening. At the beginning of ripening stored malate could provide a greater proportion of substrate than later in ripening, and during the latter its contribution was relatively low. Therefore, stored malate was not the quantitatively most important substrate utilised by respiration and ethanolic fermentation in the pericarp of grape berries during most of ripening. It is likely that sugars provide the bulk of the deficit in substrate. Further, the increase in the respiratory quotient during most of ripening does not arise from the use of malate as main respiratory substrate.


Assuntos
Etanol/química , Malatos/química , Vitis/fisiologia , Carboidratos/análise , Carboidratos/química , Dióxido de Carbono/química , Fermentação , Frutas/fisiologia , Malatos/análise , Nitrogênio/química , Consumo de Oxigênio , Proteínas de Plantas/metabolismo , Fatores de Tempo
18.
J Plant Physiol ; 169(6): 551-60, 2012 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-22317786

RESUMO

The growth characteristics of some plums and their component parts have been previously studied, as have some aspects of their developmental anatomy and composition. However, little is known about either their metabolism or about the interactions between the metabolism of their component parts. In this study we investigated these aspects in the Japanese plum Ozark Premier. Throughout fruit and seed development, changes in sugar and organic acid contents, protein composition and abundance of selected enzymes were determined. In the stone, there was a transient accumulation of vegetative storage proteins. These were subsequently mobilized and this coincided with the onset of the lignification of the stone and the start of storage protein accumulation in the seed. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was present in the seeds, even though they lacked chlorophyll, and its presence may be related to limited gas exchange. In the flesh of some fruits, phosphoenolpyruvate carboxykinase (PEPCK) and NADP malic enzyme (NADP-ME) are thought to function in the dissimilation of malate and/or citrate during ripening. However, PEPCK and NADP-ME were present in plum flesh for most of its development, although there was no net dissimilation of malate until the latter stages of ripening. There is an interaction between the developing seed and endocarp with respect to the utilization of imported sugars and amino acids. An hypothesis is presented to account for the presence of PEPCK and NADP-ME enzyme in plum flesh when there was no net dissimilation of organic acids.


Assuntos
Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Prunus/crescimento & desenvolvimento , Prunus/metabolismo , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Aminoácidos/metabolismo , Biomassa , Metabolismo dos Carboidratos , Ácido Cítrico/metabolismo , Frutas/enzimologia , Japão , Malatos/metabolismo , Peptídeos/metabolismo , Fotossíntese , Feixe Vascular de Plantas/enzimologia , Prunus/enzimologia , Ribulose-Bifosfato Carboxilase/metabolismo , Sementes/enzimologia , Solubilidade
19.
J Exp Bot ; 62(15): 5357-65, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21908472

RESUMO

In this study the abundance and location of phosphoenolpyruvate carboxykinase (PEPCK) was determined in the flesh and skin of the sweet cherry (Prunus avium L.) cultivar Durone Nero II during development. PEPCK was not present in young fruit but appeared in both tissues as the fruit increased in size. In these there was no net dissimilation of malic acid, which accounts for the bulk of their organic acid contents when PEPCK was present. To assist in understanding the function of PEPCK, the abundance of a number of other enzymes was determined. These enzymes were aspartate aminotransferase (AspAT), glutamine synthetase (GS), phosphoenolpyruvate carboxylase (PEPC), pyruvate, orthophosphate dikinase (PPDK), and ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). A potential role for PEPCK in the regulation of pH and the utilization of malate in gluconeogenesis in the flesh and skin of cherries is presented.


Assuntos
Frutas/enzimologia , Frutas/crescimento & desenvolvimento , Fosfoenolpiruvato Carboxilase/metabolismo , Prunus/enzimologia , Prunus/crescimento & desenvolvimento , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Concentração de Íons de Hidrogênio , Malatos/metabolismo , Prunus/metabolismo
20.
Plant Physiol Biochem ; 49(8): 923-30, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21741262

RESUMO

In this study some aspects of organic and amino acid metabolism in cherry endocarp and seed were investigated during their development. The abundance and location of a number of enzymes involved in these processes were investigated. These enzymes were aspartate aminotransferase (AspAT; EC:2.6.1.1), glutamine synthetase (GS; EC:6.3.1.2), phosphoenolpyruvate carboxylase (PEPC; EC:4.1.1.31), phosphoenolpyruvate carboxykinase (PEPCK; EC:4.1.1.49), and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC:4.1.1.39). There was a transient and massive accumulation of vegetative storage proteins in the endocarp. These proteins were remobilised as the endocarp lignified and at the same time that proteins were accumulated in the seed. This raised the possibility that a proportion of imported amino acids were temporarily stored in the endocarp as protein, and that these were later utilised by the seed when it started to accumulate storage proteins. Rubisco was present in the embryo and integuments of the seed although no chlorophyll was present. This is the first time that Rubisco has been detected in non-green seeds. The maximum abundance of Rubisco in the seed coincided with the deposition of seed storage proteins. A possible function for Rubisco in cherry seed is discussed. PEPCK was located in the integuments and appeared when seed storage proteins were being accumulated. In the integuments and embryo AspAT, GS, PEPC and Rubisco also appeared, or greatly increased in abundance, when seed storage proteins were being deposited.


Assuntos
Prunus/crescimento & desenvolvimento , Prunus/metabolismo , Sementes/metabolismo , Aspartato Aminotransferases/metabolismo , Metabolismo dos Carboidratos , Clorofila/metabolismo , Eletroforese em Gel de Poliacrilamida , Glutamato-Amônia Ligase/metabolismo , Malatos/metabolismo , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Extratos Vegetais/química , Proteínas de Plantas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Proteínas de Armazenamento de Sementes/metabolismo
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