Anatomical adaptations of monstera deliciosa liebm.: A tropical liana

The anatomical study focused on stem and leaf structures including epidermal features and transverse sections. The stems and leaves of the studied plants: Thickness of the epidermis(mm), cortex(mm), vascular bundles(mm), xylem(mm) and phloem(mm). The present study dealt with the study of wild species of the Brassicaceae family and included (6) species belonging to several genera except for the species Diplotaxis harra and Diplotaxis erucoides belonging to the genus Diplotaxis L in northern Iraq. The study of wind finishing focused on the finishing structures of the leaves, including epidermis, cross-sections, thickness of epidermis, cortex, vascular bundles, bark, xylem, upper and lower epidermis of leaves, meristem, spongy layer, and vascular bundles, all measured in micrometers, and number of vascular bundles. The epidermis thickness was highest in Diplotaxis harra , while Diplotaxis erucoides had the highest cortex thickness. Regarding the vascular conductivity, Diplotaxis harra was higher than Calepina regularis , and mango of the studied species. As for the xylem thickness, Diplotaxis erucoides recorded the highest value for the rest of the studied species. Regarding the bark, Diplotaxis harra recorded the highest value for the rest of the studied species, but for some vascular bundles, the highest value was for Diplotaxis erucoides . In terms of leaf cross-sections, the highest average thickness of the upper epidermis was found in Diplotaxis erucoides . As for the thickness of the lower epidermis, it was higher in Diplotaxis erucoides than in Rapistrum rugosum . In Calepina irregularis , there is no palisade layer, while Rapistrum rugosum had the highest average thickness of the palisade layer. In terms of the number of layers, Thlaspi perfoliatum had the fewest layers among the studied species. As for the spongy layer, Calepina irregularis had the highest average among the studied species, while Thlaspi perfoliatum had the lowest average. As for the vascular bundles, Thlaspi perfoliatum had the lowest average thickness, while Rapistrum rugosum had the highest average thickness among the studied species. In terms of the number of bundles, the species Diplotaxis harra had the highest rate, while the lowest rate was found in Thlaspi perfoliatum and Calepina irregularis .. Anatomical characters have been shown to be as important as phenotypic characters in isolating and identifying the Thlaspi perfoliatum, Calepina irregularis, Diplotaxis erucoides, Diplotaxis harra, Rapistrum rugosum .

In the leaves of the NAD-malic enzyme (NAD-ME)-type C4 dicot Amaranthus viridis L., there are chloroplasts in the vascular parenchyma cells (VPC), companion cells (CC), ordinary epidermal cells (EC), and guard cells (GC), as well as in the mesophyll cells (MC) and the bundle sheath cells (BSC). However, the chloroplasts of the VPC, CC, EC, and GC are smaller than those of the MC and BSC. In this study, the accumulation of photosynthetic and photorespiratory enzymes in these leaf cell types was investigated by immunogold labelling and electron microscopy. Strong labelling for phosphoenolpyruvate carboxylase was found in the MC cytosol. Weak labelling was observed in the CC and GC cytosol. Labelling for pyruvate, Pi dikinase occurred to varying degrees in the chloroplasts of all cell types except CC. Labelling for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase was detected in the chloroplasts of all cell types except MC. For both NAD-ME and the P-protein of glycine decarboxylase, intense labelling was found in the BSC mitochondria; weaker labelling was recognized in the VPC mitochondria. These data indicate that when not only the MC and BSC but also the other leaf cell types are included, the cell-specific expression of the enzymes in C4 leaves becomes more complex than has been known previously. These findings are discussed in relation to the metabolic function of epidermal and vascular bundle cells.

The distribution of solutes between epidermal, mesophyll and bundle-sheath cells in barley (Hordeum vulgare L. cv. Klaxon) leaves was studied by analysing extracts obtained from single cells with a modified pressure probe. Activity of the cytoplasmic marker enzyme, malate dehydrogenase, revealed that epidermal cell extracts were completely vacuolar in origin, but extracts from mesophyll cells also contained cytoplasmic constituents. The extracts were analysed for osmolality and the concentrations of K, Na, Ca, Cl, P, S, NO 3 − , sugars and total amino acids. Epidermal and mesophyll cell extracts had similar osmolalities but these varied between 420 and 565 mosmol, kg 1 depending on the leaf developmental stage; the osmolality of bundle-sheath extracts was approximately 100 mosmol, kg−1 lower. Under the growth conditions used, K and NO 3 − were found in all three cell types and their concentrations generally ranged between 180 and 230 mM. In contrast, Ca was almost restricted to epidermal cells, where it increased to 70 mM during leaf ageing. Phosphorus was only detectable (≥ 5 mM) in extracts from mesophyll and bundle-sheath cells, while Cl concentrations were highest in epidermal and lowest in mesophyll cell extracts. The concentrations of sugars and amino acids were close to the detection limit (approx. 2 mM) in epidermal cells but mesophyll cells contained total sugar (glucose, fructose and sucrose) of up to 78 mM and total amino-acid concentrations of up to 13.5 mM. Concentrations in bundle-sheath cells were intermediate between those in the epidermis and mesophyll.

Leaf anatomy and ultrastructure of the North American marine angiosperm<i>Phyllospadix</i>(Zosteraceae)

Mesophyll cells and bundle sheath strands were isolated rapidly from leaves of the C(4) species Digitaria pentzii Stent. (slenderstem digitgrass) by a chopping and differential filtration technique. Rates of CO(2) fixation in the light by mesophyll and bundle sheath cells without added exogenous substrates were 6.3 and 54.2 micromoles of CO(2) per milligram of chlorophyll per hour, respectively. The addition of pyruvate or phosphoenolpyruvate to the mesophyll cells increased the rates to 15.2 and 824.6 micromoles of CO(2) per milligram of chlorophyll per hour, respectively. The addition of ribose 5-phosphate increased the rate for bundle sheath cells to 106.8 micromoles of CO(2) per milligram of chlorophyll per hour. These rates are comparable to those reported for cells isolated by other methods. The K(m)(HCO(3) (-)) for mesophyll cells was 0.9 mm; for bundle sheath cells it was 1.3 mm at low, and 40 mm at higher HCO(3) (-) concentrations. After 2 hours of photosynthesis by mesophyll cells in (14)CO(2) and phosphoenolpyruvate, 88% of the incorporated (14)C was found in organic acids and 0.8% in carbohydrates; for bundle sheath cells incubated in ribose 5-phosphate and ATP, more than 58% of incorporated (14)C was found in carbohydrates, mainly starch, and 32% in organic acids. These findings, together with the stimulation of CO(2) fixation by phosphoenolpyruvate for mesophyll cells and by ribose 5-phosphate plus ATP for bundle sheath cells, and the location of phosphoenolpyruvate and ribulose bisphosphate carboxylases in mesophyll and bundle sheath cells, respectively, are in accord with the scheme of C(4) photosynthesis which places the Calvin cycle in the bundle sheath and C(4) acid formation in mesophyll cells.Starch and reducing sugars were present in both mesophyll and bundle sheath cells following a period of photosynthesis by whole leaves. However, when isolated cells were exposed to (14)CO(2) in the light, even with appropriate exogenous substrates, only bundle sheath cells accumulated appreciable amounts of labeled carbohydrates. Incubation of mesophyll cells in the light with ATP and either pyruvate and inorganic phosphate, or phosphoenolpyruvate, or 3-phosphoglycerate resulted in large increases in total carbohydrates. The 3-phosphoglycerate treatment produced the greatest increase. These results could not be explained on the basis of increased CO(2) fixation. They suggest that mesophyll cells are able to metabolize exogenously supplied 3-carbon compounds to carbohydrates, despite the apparent inability of these cells to utilize CO(2) for this purpose, and support the view that in the whole leaf 3-phosphoglycerate is transported from bundle sheath to mesophyll cells, where it is reduced to carbohydrate.Sucrose and sucrose-phosphate synthetases and invertase were localized mainly in bundle sheath cells. ADP-Glucose starch synthetase and amylase were present mainly in bundle sheath cells whereas starch phosphorylase was present mainly in mesophyll cells.

Isolated mesophyll cells and bundle sheath cells of Digitaria sanguinalis were used to study the light-absorbing pigments and electron transport reactions of a plant which possesses the C(4)-dicarboxylic acid cycle of photosynthesis. Absorption spectra and chlorophyll determinations are presented showing that mesophyll cells have a chlorophyll a-b ratio of about 3.0 and bundle sheath cells have a chlorophyll a-b ratio of about 4.5. The absorption spectrum of bundle sheath cells has a greater absorption in the 700 nm region at liquid nitrogen temperature, and there is a relatively greater amount of a pigment absorbing at 670 nm in the bundle sheath cells compared to the mesophyll cells. Fluorescence emission spectra, at liquid nitrogen temperature, of mesophyll cells have a fluorescence 730 nm-685 nm ratio of about 0.82 and bundle sheath cells have a ratio of about 2.84. The reversible light-induced absorption change in the region of P(700) absorption is similar in both cell types but bundle sheath cells exhibit about twice as much total P(700) change as mesophyll cells on a total chlorophyll basis. The delayed light emission of bundle sheath cells is about one-half that of mesophyll cells. Both mesophyll cells and bundle sheath cells evolve oxygen in the presence of Hill oxidants with the mesophyll cells exhibiting about twice the activity of bundle sheath cells, and both activities are inhibited by 1 muM 3-(3,4-dichlorophenyl)-1, 1-dimethylurea. Ferredoxin nicotinamide adenine dinucleotide phosphate reductase is present in both cells although it is about 3- or 4-fold higher in mesophyll cells than in bundle sheath cells. Glyceraldehyde 3-P dehydrogenases, both nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate, are equally distributed in the two cell types on a chlorophyll basis. Malic enzyme is localized in the bundle sheath cells.We interpret the data as evidence for the presence of a complete chloroplast electron transport system from oxygen evolution to pyridine nucleotide reduction in both mesophyll and bundle sheath cells. However, there is a quantitative difference in the distribution of photosystem I and photosystem II components in the two photosynthetic cells with about a 3-fold higher photosystem I-II ratio in the bundle sheath cells than in the mesophyll cells. A scheme is proposed to accommodate photosynthetic CO(2) fixation and electron transport activities in the mesophyll cells via a beta-carboxylation and in the bundle sheath cells via carboxylation of ribulose-1, 5-diphosphate.

The distribution of the bipartite geminivirus bean dwarf mosaic (BDMV) within tissue and cell types of systemically infected Phaseolus vulgaris and Nicotiana benthamiana plants was determined at 6, 12, and 21 days post sap-inoculation (dpi) using an immunolocalization technique with a capsid protein antibody. In both hosts, BDMV was detected in most cell types of the inoculated leaves. In systemically infected immature and mature leaves of P vulgaris (6 and 12 dpi) and in immature leaves of N. benthamiana (12 dpi), BDMV was detected in epidermal, mesophyll, bundle sheath, phloem parenchyma, and companion cells. However, by 21 dpi, BDMV appeared to have become restricted to phloem parenchyma, companion, and bundle sheath cells in newly developing leaves of infected P vulgaris plants. Two distinct BDMV infection domains were identified in both hosts: a phloem domain that included protophloem and mature phloem cells, and a nonphloem domain that included bundle sheath and mesophyll cells and, to a lesser extent, epidermal cells. BDMV showed a striking tropism for the protophloem cells of the shoot apex, and the overall number of infected phloem cells decreased sharply from the apex and upper stem to the roots. The results of this study establish that BDMV infection is not phloem-limited in either host, which is consistent with the efficient sap-transmissibility of BDMV, and suggest that the developmental stage of the host can influence the cell/tissue distribution of the virus. A model for the establishment of systemic BDMV infection in sap-inoculated plants is presented.

The intercellular distribution of assimilatory sulfate reduction enzymes between mesophyll and bundle sheath cells was analyzed in maize (Zea mays L.) and wheat (Triticum aestivum L.) leaves. In maize, a C(4) plant, 96 to 100% of adenosine 5'-phosphosulfate sulfotransferase and 92 to 100% of ATP sulfurylase activity (EC 2.7.7.4) was detected in the bundle sheath cells. Sulfite reductase (EC 1.8.7.1) and O-acetyl-l-serine sulfhydrylase (EC 4.2.99.8) were found in both bundle sheath and mesophyll cell types. In wheat, a C(3) species, ATP sulfurylase and adenosine 5'-phosphosulfate sulfotransferase were found at equivalent activities in both mesophyll and bundle sheath cells. Leaves of etiolated maize plants contained appreciable ATP sulfurylase activity but only trace adenosine 5'-phosphosulfate sulfotransferase activity. Both enzyme activities increased in the bundle sheath cells during greening but remained at negligible levels in mesophyll cells. In leaves of maize grown without addition of a sulfur source for 12 d, the specific activity of adenosine 5'-phosphosulfate sulfotransferase and ATP sulfurylase in the bundle sheath cells was higher than in the controls. In the mesophyll cells, however, both enzyme activities remained undetectable. The intercellular distribution of enzymes would indicate that the first two steps of sulfur assimilation are restricted to the bundle sheath cells of C(4) plants, and this restriction is independent of ontogeny and the sulfur nutritional status of the plants.

Carboxylation reactions and photosynthesis of carbon compounds in isolated mesophyll and bundle sheath cells of [formula omitted] (L.) Scop

The distribution of nitrite reductase (EC 1.7.7.1) and sulfite reductase (EC 1.8.7.1) between mesophyll ceils and bundle sheath cells of maize (Zea mays L. cv. Seneca 60) leaves was examined. This examination was complicated by the fact that both of these enzymes can reduce both NO‐2 and SO2‐3 In crude extracts from whole leaves, nitrite reductase activity was 6 to 10 times higher than sulfite reductase activity. Heat treatment (10 min at 55°C) caused a 55% decrease in salfite reductase activity in extracts from bundle sheath cells and mesophyll cells, whereas the loss in nitrite reductase activity was 58 and 82% in bundle sheath cells and mesophyll cell extracts, respectively. This result was explained, together with results from the literature, by the hypothesis that sulfite reductase is present in both bundle sheath cells and mesophyll cells, and that nitrite reductase is restricted to the mesophyll cells. This hypothesis was tested i) by comparing the distribution of nitrite reductase activity and sulfite reductase activity between bundle sheath and mesophyll cells with the presence of the marker enzymes ribulose‐l, 5‐bisphosphate carboxylase (EC 4.1.1.39) and phosphoe‐nolpyruvate carboxylase (EC 4.1.1.32), ii) by examining the effect of cultivation of maize plants in the dark without a nitrogen source on nitrite reductase activity and sulfite reductase activity in the two types of cells, and iii) by studying the action of S2‐on the two enzyme activities in extracts from bundle sheath and mesophyll cells. The results from these experiments are consistent with the above hypothesis.

We have determined the levels of photosystem II activity and polypeptide abundance in whole leaves and isolated bundle sheath and mesophyll cells of C(4), "C(4)-like," and C(3) species of the genus Flaveria (Asteraceae). On a chlorophyll basis, the whole leaf levels of the D1, D2, and 34-kilodalton photosystem II polypeptides were similar for each Flaveria species. Photosystem II activity varied twofold, but was not correlated with photosynthetic type (C(3) or C(4)). The bundle sheath cell levels of photosystem II activity and associated polypeptides in C(4)-like and C(4)Flaveria species were approximately one-half those observed in mesophyll cells but equivalent to those in bundle sheath cells of the C(3) species, Flaveria cronquistii. Analyses of the steady-state levels of transcripts encoding photosystem II polypeptides indicated that there were no differences in transcript abundance between mesophyll and bundle sheath cells of the C(4)Flaveria species. This pattern was in contrast to the three- to tenfold higher levels of transcripts encoding photosystem II polypeptides in mesophyll versus bundle sheath cells of maize. It is apparent that the higher mesophyll cell to bundle sheath ratio of photosystem II polypeptides in C(4)- and C(4)-like species of Flaveria is the result of higher levels of photosystem II expression in mesophyll cells rather than lower levels of expression in bundle sheath cells.

Photosynthesis in Mesophyll Protoplasts and Bundle Sheath Cells of Various Types of C4 Plants IV. Enzymes of kespiratory Metabolism and Energy Utilizing Enzymes of Photosynthetic Pathways')

Chloroplasts of maize leaves differentiate into specific bundle sheath (BS) and mesophyll (M) types to accommodate C(4) photosynthesis. Chloroplasts contain thylakoid and envelope membranes that contain the photosynthetic machineries and transporters but also proteins involved in e.g. protein homeostasis. These chloroplast membranes must be specialized within each cell type to accommodate C(4) photosynthesis and regulate metabolic fluxes and activities. This quantitative study determined the differentiated state of BS and M chloroplast thylakoid and envelope membrane proteomes and their oligomeric states using innovative gel-based and mass spectrometry-based protein quantifications. This included native gels, iTRAQ, and label-free quantification using an LTQ-Orbitrap. Subunits of Photosystems I and II, the cytochrome b(6)f, and ATP synthase complexes showed average BS/M accumulation ratios of 1.6, 0.45, 1.0, and 1.33, respectively, whereas ratios for the light-harvesting complex I and II families were 1.72 and 0.68, respectively. A 1000-kDa BS-specific NAD(P)H dehydrogenase complex with associated proteins of unknown function containing more than 15 proteins was observed; we speculate that this novel complex possibly functions in inorganic carbon concentration when carboxylation rates by ribulose-bisphosphate carboxylase/oxygenase are lower than decarboxylation rates by malic enzyme. Differential accumulation of thylakoid proteases (Egy and DegP), state transition kinases (STN7,8), and Photosystem I and II assembly factors was observed, suggesting that cell-specific photosynthetic electron transport depends on post-translational regulatory mechanisms. BS/M ratios for inner envelope transporters phosphoenolpyruvate/P(i) translocator, Dit1, Dit2, and Mex1 were determined and reflect metabolic fluxes in carbon metabolism. A wide variety of hundreds of other proteins showed differential BS/M accumulation. Mass spectral information and functional annotations are available through the Plant Proteome Database. These data are integrated with previous data, resulting in a model for C(4) photosynthesis, thereby providing new rationales for metabolic engineering of C(4) pathways and targeted analysis of genetic networks that coordinate C(4) differentiation.

Seasonal changes in leaf anatomy and ultrastructure were studied in a sward of Cynodon dactylon (L.) Pers. grown under Mediterranean field conditions and under water stress. Relative water content (RWC), leaf water potential (ψ), and specific leaf weight were determined. Anatomical measurements included leaf thickness and number and area of bundle sheath and mesophyll cells. Quantitative measurements from electron micrographs were used to evaluate the subcellular structure of mesophyll and bundle sheath cells from well-watered and water-stressed plants. In well-watered swards leaf mesophyll cell number was highest at the beginning of June, but in stressed plants the maximum was reached in the middle of July. Water stress decreased both mesophyll and bundle sheath cell areas during the experimental period, although there were no significant differences in plant water relations in autumn. Ultrastructural changes in bundle sheath cells under stress included increase in starch deposition in chloroplasts, changes in the orientation of thylakoids, and reduction in chloroplast area. Furthermore, water stress increased the cell wall thickness by 20%. Stressed mesophyll chloroplasts were characterized by an increase in the peripheral reticulum and in starch granules and a decrease in the amount of grana stacking related to a decrease in leaf sodium concentration. The number of mitochondria per mesophyll cell was increased by water stress. Longer periods of stress induced folds in the outer tangential walls in bundle sheath cells. In mesophyll cells alterations in cellular shape and in plasmalemma were observed, and the cytosol appeared to be markedly heterogeneous. In late summer the chloroplast envelope was swollen and distorted; undulating dilated thylakoids were observed and the stroma appeared less electron dense. In mitochondria, the matrix became progressively clearer. Environmental stresses influenced leaf anatomy and cell ultrastructure. Furthermore, ultrastructural changes could be related to variations in potassium and sodium contents.

Single-cell RNA-sequencing provides new insights into the cell-specific expression patterns and transcriptional regulation of photosynthetic genes in bermudagrass leaf blades