Analysis of valine uptake by Commelina mesophyll cells in a biphasic active and a diffusional component

Planta ◽  
1982 ◽  
Vol 155 (4) ◽  
pp. 335-341 ◽  
Author(s):  
Aart J. E. van Bel ◽  
Ad C. Borstlap ◽  
Anja van Pinxteren-Bazuine ◽  
Ankie Ammerlaan
Keyword(s):  
Mesophyll Cells ◽  
Diffusional Component

Ultrastructure and Senescence in an Achloroplastic Mutant of Hordeum vulgare L. cv. Dyan

1992 ◽  
Vol 50 (1) ◽  
pp. 844-845
Author(s):  
R.H.M. Cross ◽  
C.E.J. Botha ◽  
A.K. Cowan ◽  
B.J. Hartley
Keyword(s):  
Cell Wall ◽  
Hordeum Vulgare ◽  
Leaf Tissue ◽  
Ultrastructural Changes ◽  
Hordeum Vulgare L ◽  
Mesophyll Cells ◽  
Lethal Mutant ◽  
Cytoplasmic Matrix ◽  
Close Proximity ◽  
Pinocytotic Vesicles

Senescence is an ordered degenerative process leading to death of individual cells, organs and organisms. The detection of a conditional lethal mutant (achloroplastic) of Hordeum vulgare has enabled us to investigate ultrastructural changes occurring in leaf tissue during foliar senescence.Examination of the tonoplast structure in six and 14 day-old mutant tissue revealed a progressive degeneration and disappearance of the membrane, apparently starting by day six in the vicinity of the mitochondria associated with the degenerating proplastid (Fig. 1.) where neither of the plastid membrane leaflets is evident (arrows, Fig. 1.). At this stage there was evidence that the mitochondrial membranes were undergoing retrogressive changes, coupled with disorganization of cristae (Fig. 2.). Proplastids (P) lack definitive prolamellar bodies. The cytoplasmic matrix is largely agranular, with few endoplasmic reticulum (ER) cisternae or polyribosomal aggregates. Interestingly, large numbers of actively-budding dictysomes, associated with pinocytotic vesicles, were observed in close proximity to the plasmalemma of mesophyll cells (Fig. 3.). By day 14 however, mesophyll cells showed almost complete breakdown of subcellular organelle structure (Fig. 4.), and further evidence for the breakdown of the tonoplast. The final stage of senescence is characterized by the solubilization of the cell wall due to expression and activity of polygalacturonase and/or cellulose. The presence of dictyosomes with associated pinocytotic vesicles formed from the mature face, in close proximity to both the plasmalemma and the cell wall, would appear to support the model proposed by Christopherson for the secretion of cellulase. This pathway of synthesis is typical for secretory glycoproteins.

Structural aspects of tracheary element differentiation in suspension cultures of Zinnia elegans

1989 ◽  
Vol 47 ◽  
pp. 768-769
Author(s):  
C. H. Haigler ◽  
A. W. Roberts
Keyword(s):  
Tracheary Element ◽  
Vesicle Fusion ◽  
Zinnia Elegans ◽  
Cellulose Synthesis ◽  
Tracheary Elements ◽  
Animal Cells ◽  
Mesophyll Cells ◽  
Fixation Techniques ◽  
Localized Patterns ◽  
Structural Aspects

Tracheary elements, the water-conducting cells in plants, are characterized by their reinforced walls that became thickened in localized patterns during differentiation (Fig. 1). The synthesis of this localized wall involves abundant secretion of Golgi vesicles that export preformed matrix polysaccharides and putative proteins involved in cellulose synthesis. Since the cells are not growing, some kind of endocytotic process must also occur. Many researchers have commented on where exocytosis occurs in relation to the thickenings (for example, see), but they based their interpretations on chemical fixation techniques that are not likely to provide reliable information about rapid processes such as vesicle fusion. We have used rapid freezing to more accurately assess patterns of vesicle fusion in tracheary elements. We have also determined the localization of calcium, which is known to regulate vesicle fusion in plant and animal cells.Mesophyll cells were obtained from immature first leaves of Zinnia elegans var. Envy (Park Seed Co., Greenwood, S.C.) and cultured as described previously with the following exceptions: (a) concentration of benzylaminopurine in the culture medium was reduced to 0.2 mg/l and myoinositol was eliminated; and (b) 1.75ml cultures were incubated in 22 x 90mm shell vials with 112rpm rotary shaking. Cells that were actively involved in differentiation were harvested and frozen in solidifying Freon as described previously. Fractures occurred preferentially at the cell/planchet interface, which allowed us to find some excellently-preserved cells in the replicas. Other differentiating cells were incubated for 20-30 min in 10(μM CTC (Sigma), an antibiotic that fluoresces in the presence of membrane-sequestered calcium. They were observed in an Olympus BH-2 microscope equipped for epi-fluorescence (violet filter package and additional Zeiss KP560 barrier filter to block chlorophyll autofluorescence).

STRUCTURAL-FUNCTIONAL PECULIARITIES OF LEAF MESOPHYLL CELLS OF TRITICUM AESTIVUM CULTIVARS WITH DIFFERENT COLD/HEAT TOLERANCE UNDER SHORT-TERM TEMPERATURE STRESSES

Tsitologiya ◽  
2018 ◽  
Vol 60 (2) ◽  
pp. 128-135 ◽  
Author(s):  
L. M. Babenko ◽  
◽  
N. N. Scherbatiuk ◽  
D. A. Klimchuk ◽  
I. V. Kosakovskaya ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Heat Tolerance ◽  
Short Term ◽  
Temperature Stresses ◽  
Mesophyll Cells ◽  
Leaf Mesophyll

scholarly journals Four Mutant Alleles Elucidate the Role of the G2 Protein in the Development of C4 and C3 Photosynthesizing Maize Tissues

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 787-797
Author(s):  
Lizzie Cribb ◽  
Lisa N Hall ◽  
Jane A Langdale
Keyword(s):  
Cell Types ◽  
Bundle Sheath ◽  
Primary Role ◽  
Ribulose Bisphosphate Carboxylase ◽  
Sheath Cell ◽  
Mesophyll Cells ◽  
Phenotypic Data ◽  
Bisphosphate Carboxylase ◽  
Bundle Sheath Cell

Abstract Maize leaf blades differentiate dimorphic photosynthetic cell types, the bundle sheath and mesophyll, between which the reactions of C4 photosynthesis are partitioned. Leaf-like organs of maize such as husk leaves, however, develop a C3 pattern of differentiation whereby ribulose bisphosphate carboxylase (RuBPCase) accumulates in all photosynthetic cell types. The Golden2 (G2) gene has previously been shown to play a role in bundle sheath cell differentiation in C4 leaf blades and to play a less well-defined role in C3 maize tissues. To further analyze G2 gene function in maize, four g2 mutations have been characterized. Three of these mutations were induced by the transposable element Spm. In g2-bsd1-m1 and g2-bsd1-s1, the element is inserted in the second intron and in g2-pg14 the element is inserted in the promoter. In the fourth case, g2-R, four amino acid changes and premature polyadenylation of the G2 transcript are observed. The phenotypes conditioned by these four mutations demonstrate that the primary role of G2 in C4 leaf blades is to promote bundle sheath cell chloroplast development. C4 photosynthetic enzymes can accumulate in both bundle sheath and mesophyll cells in the absence of G2. In C3 tissue, however, G2 influences both chloroplast differentiation and photosynthetic enzyme accumulation patterns. On the basis of the phenotypic data obtained, a model that postulates how G2 acts to facilitate C4 and C3 patterns of tissue development is proposed.

scholarly journals Light regulates stomatal development by modulating paracrine signaling from inner tissues

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shenqi Wang ◽  
Zimin Zhou ◽  
Rini Rahiman ◽  
Grace Sheen Yee Lee ◽  
Yuan Kai Yeo ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Gas Exchange ◽  
Cell Lineage ◽  
Developmental Outcomes ◽  
External Factors ◽  
Light Signaling ◽  
Stomatal Development ◽  
Paracrine Signaling ◽  
Mesophyll Cells ◽  
Light Signals

AbstractDevelopmental outcomes are shaped by the interplay between intrinsic and external factors. The production of stomata—essential pores for gas exchange in plants—is extremely plastic and offers an excellent system to study this interplay at the cell lineage level. For plants, light is a key external cue, and it promotes stomatal development and the accumulation of the master stomatal regulator SPEECHLESS (SPCH). However, how light signals are relayed to influence SPCH remains unknown. Here, we show that the light-regulated transcription factor ELONGATED HYPOCOTYL 5 (HY5), a critical regulator for photomorphogenic growth, is present in inner mesophyll cells and directly binds and activates STOMAGEN. STOMAGEN, the mesophyll-derived secreted peptide, in turn stabilizes SPCH in the epidermis, leading to enhanced stomatal production. Our work identifies a molecular link between light signaling and stomatal development that spans two tissue layers and highlights how an environmental signaling factor may coordinate growth across tissue types.

scholarly journals Light and CO2 Modulate the Accumulation and Localization of Phenolic Compounds in Barley Leaves

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 385
Author(s):  
Lena Hunt ◽  
Karel Klem ◽  
Zuzana Lhotáková ◽  
Stanislav Vosolsobě ◽  
Michal Oravec ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Phenolic Compounds ◽  
Co2 Concentration ◽  
Environmental Stressors ◽  
Low Light ◽  
Mesophyll Cells ◽  
Stress Prevention ◽  
Tolerant Variety ◽  
Barley Leaves

Barley (Hordeum vulgare) accumulates phenolic compounds (PhCs), which play a key role in plant defense against environmental stressors as antioxidants or UV screening compounds. The influence of light and atmospheric CO2 concentration ([CO2]) on the accumulation and localization of PhCs in barley leaves was examined for two varieties with different tolerances to oxidative stress. PhC localization was visualized in vivo using fluorescence microscopy. Close relationships were found between fluorescence-determined localization of PhCs in barley leaves and PhC content estimated using liquid chromatography coupled with mass spectroscopy detection. Light intensity had the strongest effect on the accumulation of PhCs, but the total PhC content was similar at elevated [CO2], minimizing the differences between high and low light. PhCs localized preferentially near the surfaces of leaves, but under low light, an increasing allocation of PhCs in deeper mesophyll layers was observed. The PhC profile was significantly different between barley varieties. The relatively tolerant variety accumulated significantly more hydroxycinnamic acids, indicating that these PhCs may play a more prominent role in oxidative stress prevention. Our research presents novel evidence that [CO2] modulates the accumulation of PhCs in barley leaves. Mesophyll cells, rather than epidermal cells, were most responsive to environmental stimuli in terms of PhC accumulation.

Incorporation of [14C]Phenylalanine and [14C] Cinnamic Acid into Leaf Pieces and Mesophyll Protoplasts from Oat Primary Leaves for Studies on Flavonoid Metabolism at the Tissue and Cell Level

1981 ◽  
Vol 36 (3-4) ◽  
pp. 222-233 ◽  
Author(s):  
Margareta Proksch
Keyword(s):  
Cinnamic Acid ◽  
Pulse Labelling ◽  
Acid Solutions ◽  
Cell Level ◽  
Abaxial Epidermis ◽  
Mesophyll Cells ◽  
Tissue Specific ◽  
Mesophyll Protoplasts ◽  
Main Site ◽  
End Products

When the abaxial epidermis was peeled from 5 to 6 day old oat primary leaves, and 3 cm segments were floated on radioactive phenylalanine or cinnamic acid solutions, more than 90 per cent of the radioactivity was incorporated within 3 to 7 h depending on the developmental stage of the leaf. C-glycosylflavones were labelled within 15 min and radioactivity in these compounds increased for several hours. Pulse labelling and pulse chase experiments with either phenylalanine or cinnamic acid, unequivocally demonstrate that oat flavones are stable end products of metabolism. However, this procedure does not distinguish between sequential biosynthesis of various flavones and their interconversion. Cinnamic acid was more efficiently (ca. 20 x) converted into oat leaf flavones than was phenylalanine, when the precursor was fed to leaf pieces, and flavones recovered from mesophyll protoplasts. Different labelling patterns were obtained with whole leaf segments and protoplasts which apparently reflect differences in tissue specific flavone biosynthesis of mesophyll and epidermis. Isolated mesophyll protoplasts incubated with [14C]cinnamic acid synthesize 14C-labelled flavones characteristic of the mesophyll, as well as several unidentified phenylpropanoid derivatives not found in the intact tissue. Data suggest that photosynthetically active mesophyll cells are a main site of tissue specific flavone biosynthesis

scholarly journals Transmission of Engineered Plastids in Sugarcane, a C4 Monocotyledonous Plant, Reveals that Sorting of Preprogrammed Progenitor Cells Produce Heteroplasmy

Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 26
Author(s):  
Ghulam Mustafa ◽  
Muhammad Sarwar Khan
Keyword(s):  
Progenitor Cells ◽  
Plastid Transformation ◽  
Bundle Sheath ◽  
Homologous Sequence ◽  
Regeneration System ◽  
Mesophyll Cells ◽  
Transgenic Sugarcane ◽  
Bundle Sheath Cells ◽  
Dicotyledonous Plants ◽  
Species Specific

We report here plastid transformation in sugarcane using biolistic transformation and embryogenesis-based regeneration approaches. Somatic embryos were developed from unfurled leaf sections, containing preprogrammed progenitor cells, to recover transformation events on antibiotic-containing regeneration medium. After developing a proficient regeneration system, the FLARE-S (fluorescent antibiotic resistance enzyme, spectinomycin and streptomycin) expression cassette that carries species-specific homologous sequence tails was used to transform plastids and track gene transmission and expression in sugarcane. Plants regenerated from streptomycin-resistant and genetically confirmed shoots were subjected to visual detection of the fluorescent enzyme using a fluorescent stereomicroscope, after genetic confirmation. The resultant heteroplasmic shoots remained to segregate on streptomycin-containing MS medium, referring to the unique pattern of division and sorting of cells in C4 monocotyledonous compared to C3 monocotyledonous and dicotyledonous plants since in sugarcane bundle sheath and mesophyll cells are distinct and sort independently after division. Hence, the transformation of either mesophyll or bundle sheath cells will develop heteroplasmic transgenic plants, suggesting the transformation of both types of cells. Whilst developed transgenic sugarcane plants are heteroplasmic, and selection-based regeneration protocol envisaging the role of division and sorting of cells in the purification of transplastomic demands further improvement, the study has established many parameters that may open up exciting possibilities to express genes of agricultural or pharmaceutical importance in sugarcane.

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