Effect of sucrose starvation on sycamore (Acer pseudoplatanus) cell carbohydrate and Pi status.
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ABSTRACT:
SUBMITTER: Rebeille F
PROVIDER: S-EPMC1144765 | biostudies-other | 1985 Mar
REPOSITORIES: biostudies-other
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Project description:Trees regenerating in the understory respond to increased availability of light caused by gap formation by undergoing a range of morphological and physiological adjustments. These adjustments include the production of thick, sun-type leaves containing thicker mesophyll and longer palisade cells than in shade-type leaves. We asked whether in the shade-regenerating tree Acer pseudoplatanus, the increase in leaf thickness and expansion of leaf tissues are possible also in leaves that had been fully formed prior to the increase in irradiance, a response reported so far only for a handful of species. We acclimated potted seedlings to eight levels (from 1 to 100%) of solar irradiance and, in late summer, transferred a subset of them to full sunlight. Within 30 days, the shaded leaves increased leaf mass per area and became thicker mostly due to elongation of palisade cells, except for the most shaded individuals which suffered irreversible photo-oxidative damage. This anatomical acclimation was accompanied by partial degradation of chlorophyll and a transient decline in photosynthetic efficiency of PSII (Fv/FM). These effects were related to the degree of pre-shading. The Fv/FM recovered substantially within the re-acclimation period. However, leaves of transferred plants were shed significantly earlier in the fall, indicating that the acclimation was not fully effective. These results show that A. pseudoplatanus is one of the few known species in which mature leaves may re-acclimate anatomically to increased irradiance. This may be a potentially important mechanism enhancing utilization of gaps created during the growing season.
| S-EPMC9090708 | biostudies-literature
Project description:Trees regenerating in the understory respond to increased availability of light caused by gap formation by undergoing a range of morphological and physiological adjustments. These adjustments include the production of thick, sun-type leaves containing thicker mesophyll and longer palisade cells than in shade-type leaves. We asked whether in the shade-regenerating tree Acer pseudoplatanus, the increase in leaf thickness and expansion of leaf tissues are possible also in leaves that are already fully formed, a response reported so far only for a handful of species. We acclimated potted seedlings to eight levels (from 1 to 100%) of solar irradiance and, in late summer, transferred a subset of them to full sunlight. Within 30 days, the pre-shaded leaves increased leaf mass per area and became thicker mostly due to the elongation of palisade cells, except for the most shaded individuals which suffered irreversible photo-oxidative damage. This anatomical acclimation was accompanied by a transient decline in photosynthetic efficiency of PSII (Fv/FM), the magnitude of which was related to the degree of pre-shading. The Fv/FM recovered substantially within the re-acclimation period. However, leaves of transferred plants were shed earlier in the fall, indicating that the acclimation was not fully effective. These results show that A. pseudoplatanus is one of the few known species in which mature leaves may re-acclimate anatomically to increased irradiance. This may be an important mechanism enhancing utilization of gaps created during the growing season.
| S-EPMC9568483 | biostudies-literature
Project description:Acer pseudoplatanus Genome sequencing and assembly
| PRJNA960919 | ENA
Project description:Fusicoccin (FC), a natural diterpene glucoside able to stimulate electrogenic H+ extrusion in higher plants, has been shown to stimulate the phosphorylation of a polypeptide of molecular mass approx. 33 kDa in intact cultured cells of sycamore (Acer pseudoplatanus). The effect is specific, rapid and insensitive to cycloheximide. The presence of the 33 kDa polypeptide and the stimulation by FC have been observed in SDS-containing cell homogenates and in the microsomal and soluble fractions after cell fractionation.
| S-EPMC1146646 | biostudies-other
Project description:Copper-deprived sycamore (Acer pseudoplatanus) cells do not excrete molecules of active laccase in their culture medium. In the range of 2-100 micrograms of copper initially present per litre of nutrient solution, the total laccase activity measured in the cell suspensions at the end of the exponential phase of growth was closely proportional to the amount of added copper. However, copper-deprived cells excreted the laccase apoprotein (laccase without copper) at the same rate as copper-supplied cells excreted the active, copper-containing, laccase. When the culture medium was initially supplied with limiting amounts of copper, the active laccase was excreted until all copper molecules were metabolized. Thereafter, the laccase apoprotein was excreted. Consequently, at the end of the exponential phase of growth, the cell supernatants contained a mixture of apoprotein and copper-containing laccase. After purification and concentration, this mixture of copper-containing laccase (blue) and laccase apoprotein (slightly yellow) showed a yellow-green colour. Under copper-limiting culture conditions an equivalent decrease of Type 1, Type 2 and Type 3 Cu2+ was observed. Addition of copper to copper-deficient enzyme solutions does not result in a recovery of the enzyme activity. However, when added to copper-deficient sycamore-cell suspensions, copper induced a recovery of the excretion of active enzyme, at a normal rate, within about 10 h. The first molecules of active laccase were excreted after 3-4 h.
| S-EPMC1147023 | biostudies-other
Project description:A laccase-type polyphenol oxidase is excreted by sycamore cells (Acer pseudoplatanus L.) cells. The enzyme has been purified by classical purification techniques. It is a blue copper protein of Mr 97 000, containing 45% carbohydrate and 0.24% copper. This protein consists of one single unit and the copper content corresponds to four copper atoms per protein molecule. The specific activity of the purified extracellular sycamore-cell laccase measured at pH 6.6 (optimum pH) and in the presence of 20mM-4-methhylcatechol (optimum substrate conditions) corresponded to an oxygen uptake of 32 000 nmol of O2/min per mg of protein. Under these conditions, the catalytic-centre activity of the enzyme reached 100 s-1. The excretion of laccase by sycamore cells is significant, being about 2% of the total protein synthesized by the cells during the exponential phase of growth, and is independent of cell growth. The physiological significance and the problems raised by the passage of this protein across the cytoplasmic membrane are discussed.
| S-EPMC1154116 | biostudies-other
Project description:The availability of methods to fractionate non-green plastids and to prepare their limiting envelope membranes [Alban, Joyard & Douce (1988) Plant Physiol. 88, 709-717] allowed a detailed analysis of the biosynthesis of lysophosphatidic acid, phosphatidic acid, diacylglycerol and monogalactosyl-diacylglycerol (MGDG) in two different types of non-green starch-containing plastids: plastids isolated from cauliflower buds and amyloplasts isolated from sycamore cells. An enzyme [acyl-ACP (acyl carrier protein):sn-glycerol 3-phosphate acyltransferase) recovered in the soluble fraction of non-green plastids transfers oleic acid from oleoyl-ACP to the sn-1 position of sn-glycerol 3-phosphate to form lysophosphatidic acid. Then a membrane-bound enzyme (acyl-ACP:monoacyl-sn-glycerol 3-phosphate acyltransferase), localized in the envelope membrane, catalyses the acylation of the available sn-2 position of 1-oleoyl-sn-glycerol 3-phosphate by palmitic acid from palmitoyl-ACP. Therefore both the soluble phase and the envelope membranes are necessary for acylation of sn-glycerol 3-phosphate. The major difference between cauliflower (Brassica oleracea) and sycamore (Acer pseudoplatanus) membranes is the very low level of phosphatidate phosphatase activity in sycamore envelope membrane. Therefore, very little diacylglycerol is available for MGDG synthesis in sycamore, compared with cauliflower. These findings are consistent with the similarities and differences described in lipid metabolism of mature chloroplasts from 'C18:3' and 'C16:3' plants (those with MGDG containing C18:3 and C16:3 fatty acids). Sycamore contains only C18 fatty acids in MGDG, and the envelope membranes from sycamore amyloplasts have a low phosphatidate phosphatase activity and therefore the enzymes of the Kornberg-Pricer pathway have a low efficiency of incorporation of sn-glycerol 3-phosphate into MGDG. By contrast, cauliflower contains MGDG with C16:3 fatty acid, and the incorporation of sn-glycerol 3-phosphate into MGDG by the enzymes associated with envelope membranes is not limited by the phosphatidate phosphatase. These results demonstrate that: (1) non-green plastids employ the same biosynthetic pathway as that previously established for chloroplasts (the formation of glycerolipids is a general property of all plastids, chloroplasts as well as non-green plastids), (2) the envelope membranes are the major structure responsible for the biosynthesis of phosphatidic acid, diacylglycerol and MGDG, and (3) the enzymes of the envelope Kornberg-Pricer pathway have the same properties in non-green starch-containing plastids as in mature chloroplasts from C16:3 and C18:3 plants.
| S-EPMC1138585 | biostudies-other
Project description:The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by plants of Acer pseudoplatanus imported from the United Kingdom (UK) as: (a) 1- to 7-year-old bare root plants for planting, (b) 1- to 7-year-old plants in pots and (c) bundles of 1- to 2-year-old whips and seedlings, taking into account the available scientific information, including the technical information provided by the UK. All pests associated with the commodity were evaluated against specific criteria for their relevance for this opinion. Six EU quarantine pests and four pests not regulated in the EU fulfilled all relevant criteria and were selected for further evaluation. For these pests, the risk mitigation measures implemented in the technical dossier from the UK were evaluated taking into account the possible limiting factors. For the selected pests, an expert judgement is given on the likelihood of pest freedom taking into consideration the risk mitigation measures acting on the pest, including uncertainties associated with the assessment. The degree of pest freedom varies among the pests evaluated, with Meloidogyne mali or M. fallax being the pest most frequently expected on the imported plants. The Expert Knowledge Elicitation indicated with 95% certainty that 9,792 or more plants in pots per 10,000 will be free from Meloidogyne mali or M. fallax.
| S-EPMC10323731 | biostudies-literature
Project description:Movement of paramagnetic Mn2+ into sycamore (Acer pseudoplatanus) cells has been indirectly examined by observing the line broadening exhibited in its 31P n.m.r. spectra. Mn2+ was observed to pass into the vacuole, while exhibiting a very minor accumulation in the cytoplasm. With time, gradual leakage of phosphate from the vacuole to the cytoplasm was observed along with an increase in glucose-6-phosphate. Anoxia did not appear to affect the relative distribution of Mn2+ in the cytoplasm and vacuole. Under hypoxic conditions restriction of almost all movement of Mn2+ across the plasmalemma as well as the tonoplast was observed. In contrast, maize root tips showed entry and complete complexation of nucleotide triphosphate by Mn2+ during hypoxia. The rate of passage of Mn2+ across the tonoplast in both sycamore and maize root cells is approximately the same. However, the rates of facilitated movement across the respective plasma membranes appear to differ. More rapid movement of Mn2+ across the plasmalemma in maize root tip cells allows a gradual build-up of metal ion in the cytoplasm prior to its diffusion across the tonoplast. Sycamore cells undergo a slower uptake of Mn2+ into their cytoplasms (comparable with the rate of diffusion through the tonoplast), so little or no observable accumulation of Mn2+ is observed in this compartment.
| S-EPMC1149159 | biostudies-other
Project description:Protoplasts obtained from sycamore (Acer pseudoplatanus) cell suspensions were found to be highly intact and to retain a high rate of O2 consumption. If the protoplasts were taken up and expelled through a fine nylon mesh, all the protoplasts were ruptured, leaving the fragile amyloplasts largely intact. Distribution of enzymes of glycolysis in plastids and soluble phase of sycamore protoplasts indicated that the absolute maximum activity for each glycolytic enzyme under optimum conditions exceeded the estimates of the maximal rate at which sycamore cells oxidize triose phosphate. Passage of protoplasts through the fine nylon mesh produced a 3-5-fold decrease in O2 consumption. However, addition of saturating amounts of respiratory substrates and ADP restored an O2 consumption equal to that observed with uncoupled intact protoplasts. Taken together, these results demonstrated that neither the overall capacity of the glycolytic enzymes in sycamore cells nor the availability of respiratory substrates for the mitochondria is ultimately responsible for determining the rate of uncoupled respiration in sycamore cells.
| S-EPMC1153064 | biostudies-other