Inclusions and wall deposits in cells of plants infected with oat necrotic mottle virus

1974 ◽  
Vol 52 (3) ◽  
pp. 621-626 ◽  
Author(s):  
C. C. Gill
Keyword(s):  
Cell Wall ◽  
Avena Sativa ◽  
Inclusion Bodies ◽  
Mottle Virus ◽  
Mesophyll Cells ◽  
Virus Like Particles ◽  
Green Tissue ◽  
Dark Green ◽  
Pale Green ◽  
In Cells

Virus-like particles and two types of inclusion bodies were found in cells of leaves of oats, Avena sativa L., and Canada bluegrass, Poa compressa L., infected with oat necrotic mottle virus. The particles and inclusion bodies were seen in pale green tissue and in most samples of dark green tissue of mottled, mature oat leaves, but were seen only in the pale green tissue of immature leaves. There was also evidence of infection in oat roots.Tubules and (or) vesicles occurred between the cell wall and the plasmalemma (boundary formation) in many mesophyll cells of infected, mature bluegrass and oat leaves. Three types of abnormal deposits, localized, extensive, and fibrillar, also occurred between the wall and the plasmalemma in many of these cells. The extensive and fibrillar deposits were more common in bluegrass than in oats.

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.

Exploration of the forbidden regions of the Ramachandran plot (ϕ-ψ) with QTAIM

2017 ◽  
Vol 19 (38) ◽  
pp. 26423-26434 ◽  
Author(s):  
Roya Momen ◽  
Alireza Azizi ◽  
Lingling Wang ◽  
Yang Ping ◽  
Tianlv Xu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Peptide Structure ◽  
Ramachandran Plot ◽  
Left Response ◽  
Forbidden Regions ◽  
Dark Green ◽  
Ramachandran Plots ◽  
Pale Green

Left: Response β is defined as: β = arccos(e̲2·y̲) with β* = arccos(e̲1·y̲). Right: QTAIM interpreted Ramachandran plots {(βϕ,βϕ*)-(βψ,βψ*)} ‘-’ is a hyphen and not a subtraction sign. Pale green and dark green crosses indicate the glycine, pink and red pluses represent the remaining amino acids (a.a.) in the magainin peptide structure.

scholarly journals Structural Changes in Lettuce Seed During Germination at High Temperature Altered by Genotype, Seed Maturation Temperature, and Seed Priming

2008 ◽  
Vol 133 (2) ◽  
pp. 300-311 ◽  
Author(s):  
Yu Sung ◽  
Daniel J. Cantliffe ◽  
Russell T. Nagata ◽  
Warley M. Nascimento
Keyword(s):  
Cell Wall ◽  
High Temperature ◽  
Structural Changes ◽  
Anatomical Study ◽  
Seed Priming ◽  
Seed Maturation ◽  
Mechanical Resistance ◽  
Lettuce Seed ◽  
Endosperm Cell ◽  
Dark Green

To investigate thermotolerance in seeds of lettuce (Lactuca sativa L.), primed, nonprimed, or seeds matured at 20/10 and 30/20 °C (day/night on a 12-h photoperiod) were imbibed at 36 °C for various periods and then dissected. Structural changes in seed coverings in front of the radicle tip were observed during germination at high temperature. Thermotolerant genotypes, ‘Everglades’ and PI 251245, were compared with a thermosensitive cultivar, ‘Dark Green Boston’. In all seeds that germinated, regardless of seed maturation temperature or priming, a crack appeared on one side of the cap tissue (constriction of the endosperm membrane near the basal end of the seed) at the micropylar region and the endosperm separated from the integument in front of the radicle tip. Additional changes took place during imbibition in these seeds; the protein bodies in the vacuoles enlarged and gradually depleted, large empty vacuoles formed, the cytoplasm condensed, the endosperm shrank, the endosperm cell wall dissolved and ruptured, and then the radicle elongated toward this ruptured area. The findings suggested that the endosperm layer presented mechanical resistance to germination in seeds that could not germinate at 36 °C. Weakening of this layer was a prerequisite to radicle protrusion at high temperature. Seeds of ‘Dark Green Boston’, ‘Everglades’, and PI 251245 matured at 30/20 °C had greater thermotolerance than those matured at 20/10 °C. Results of the anatomical study indicated that the endosperm cell walls in front of the radicle of seeds matured at 30/20 °C were more readily disrupted and ruptured during imbibition than seeds matured at 20/10 °C, suggesting a reason why these seeds could germinate quickly at supraoptimal temperatures. Similar endosperm structural alterations also were observed in primed seeds. Priming led to rapid and uniform germination, circumventing the inhibitory effects of high temperatures. From anatomical studies conducted to identify and characterize thermotolerance in lettuce seed germination, we observed that genotype, seed maturation temperature, or seed priming had the ability to reduce physical resistance of the endosperm by weakening the cell wall and by depleting stored reserves leading to cell collapse.

Association of malva vein-clearing virus and rhabdoviruslike particles with mottle and vein clearing of malva plants

1986 ◽  
Vol 64 (1) ◽  
pp. 85-89 ◽  
Author(s):  
Maria-Ivone C. Henriques ◽  
Fernando S. Henriques
Keyword(s):  
Inclusion Bodies ◽  
Inner Core ◽  
Dense Body ◽  
Mesophyll Cells ◽  
Cytoplasmic Inclusions ◽  
Thin Sections ◽  
Phloem Parenchyma ◽  
Vein Clearing ◽  
Perinuclear Space ◽  
Parenchyma Cells

Thin sections of malva (Malva sp.) leaves collected in the field and showing mottle and vein-clearing symptoms were examined by electron microscopy. Cytoplasmic inclusions typical of potyvirus and consisting of pinwheels, laminated aggregates, and scrolls were readily observed. In addition, rhabdoviruslike particles were also seen in the perinuclear space of phloem parenchyma cells and within membranous sacs scattered throughout the cytoplasm of other vascular bundle cells. Occasionally rhabdoparticles could be found embedded in an amorphous electron-dense body located within the cell vacuole. The rhabdovirus particles, approximately 75 × 300 nm, were bound by a membrane with outer projections and had an inner core displaying cross striations. The cytoplasm of infected mesophyll cells had chloroplasts containing large amorphous inclusion bodies and had extensive membranous tubules that were frequently associated with the potyvirus inclusions. These ultrastructural aspects, the size of the particles, and the data on host range indicate that malva plants under study were doubly infected by viruses which were tentatively identified as malva vein-clearing virus and a previously undescribed rhabdovirus.

scholarly journals Cell wall and enzyme changes during the graviresponse of the leaf-sheath pulvinus of oat (Avena sativa).

1990 ◽  
Vol 94 (2) ◽  
pp. 411-416 ◽  
Author(s):  
D M Gibeaut ◽  
N Karuppiah ◽  
Chang S-R ◽  
T G Brock ◽  
B Vadlamudi ◽  
...  
Keyword(s):  
Cell Wall ◽  
Avena Sativa ◽  
Leaf Sheath ◽  
Enzyme Changes

Triticum tauschii: reaction to the take-all fungus (Gaeumannomyces graminis var. tritici)

1993 ◽  
Vol 44 (4) ◽  
pp. 745 ◽  
Author(s):  
RF Eastwood ◽  
JF Kollmorgen ◽  
M Hannah
Keyword(s):  
New Zealand ◽  
Avena Sativa ◽  
Seed Weight ◽  
Triticum Turgidum ◽  
Experimental Methods ◽  
Genetic Effects ◽  
Gaeumannomyces Graminis ◽  
Green Tissue ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

Reactions of 398 accessions of Triticum tawchii to the take-all fungus [Gaeumannomyces graminis var. tritici (Ggt] were assessed. Nineteen accessions were selected for more detailed studies. T. tauschii accessions were identified that had less tissue blackening and more remaining green tissue when challenged by the fungus than the susceptible T. aestivum cv. Condor. However, tissue blackening in the T. tauschii accessions was much greater than that in Avena sativa cv. New Zealand Cape. Synthetic allohexaploid wheats produced from different Triticum turgidum var. durum (genome AABB) accessions and accessions of T. tauschii (genome DD) which had low tissue blackening or high remaining green tissue had more tissue blackening and less remaining green tissue than the T. tauschii parents. The potential of this material for breeding take-all resistant wheats together with experimental methods to minimize the possible confounding effects of seed weight, seed source and genetic effects are discussed.

Voltage-Dependence of Extracellular Ca2+-Induced Modification in Properties of the Inward Rectifying K+ Channels in the Plasma Membrane of Mesophyll Protoplasts of Avena sativa

1996 ◽  
Vol 23 (3) ◽  
pp. 349 ◽  
Author(s):  
J Kourie
Keyword(s):  
Plasma Membrane ◽  
Time Constant ◽  
Avena Sativa ◽  
Voltage Dependence ◽  
Membrane Current ◽  
Time Dependent ◽  
Mesophyll Cells ◽  
K Channels ◽  
Current Passing ◽  
K Current

Data obtained using the whole-celi configuration of the patch-clamp technique reveal that characteristics of the inward rectifying K+ current across the plasma membrane of protoplasts isolated from mesophyll cells of leaves of oat (Avena sativa) are modified by increasing concentrations or removing the extracellular Ca2+. The whole-cell membrane current reveals two components. The first component an initial current II* which is the sum of two currents: (a) a linear ohmic leak current passing through non-gated channels, liNGC, and (b) a rectifying inward K+ current passing through inward rectifying gated K+ channels, IKi, that are instantaneously open. The second component of the membrane current at the steady state Iss is a time-dependent K+ current IKss defined as Iss-IiNGC and passes through inward rectifying gated K+ channels. The tail K+ current, IKT, is also defined as IT-IiNGC. Raising external calcium concentration, [Ca2+]o, from 0.1 mM to 10 mM blocked the inward rectifying currents IKi, IKss and IKT. The voltage-dependence of the activation time constant (τa) for time-dependent KC current IKss was not altered significantly by increasing [Ca2+]o whereas the deactivation time constant (τd) of the IKT increased from 16 ms to 30 ms at a Vm of -100 mV. Removal of [Ca2+]o increased the amplitude and altered the characteristics of the inward rectifying K+ current. Ten minutes after the removal of [Ca2+]o the increase in IKi was 3.5-fold larger than the increase in IKss. Furthermore, removing [Ca2+]o hastened the activation of IKss and the deactivation of IKT. However, the deactivation time constant (Td) remained dependent on membrane voltage (Vm). Extracellular Ca2+ may modulate the function of mesophyll cells by regulating K+ transport through the inward rectifying K+ channels and this may have significant implications for photosynthesis and cell expansion.

scholarly journals Changes in phenolic acids and stilbenes induced in embryogenic cell cultures of Norway spruce by two fractions of Sirococcus strobilinus mycelian

2011 ◽  
Vol 57 (No. 1) ◽  
pp. 1-7 ◽  
Author(s):  
J. Malá ◽  
M. Hrubcová ◽  
P. Máchová ◽  
H. Cvrčková ◽  
O. Martincová ◽  
...  
Keyword(s):  
Cell Wall ◽  
Norway Spruce ◽  
Phenolic Acids ◽  
Cell Cultures ◽  
Total Content ◽  
Cell Suspension Cultures ◽  
Moderate Increase ◽  
Embryogenic Cell ◽  
Defence Responses ◽  
In Cells

We examined defence responses in embryogenic cell suspension cultures of Norway spruce (Picea abies [L.] Karst) elicited by intracellular protein and cell wall fractions (PF and WF, respectively) prepared from mycelia of the fungus Sirococcus strobilinus Preuss focusing on changes in (soluble and cell wall-bound) phenolic and stilbene concentrations. Treatment with both preparations induced an increase in the total contents of phenolic acids in Norway spruce cells and variations in the levels of stilbene glycosides. More rapid and intense induction of defence response was observed in cells after WF application. The contents of soluble phenolic acids (especially benzoic acid derivatives) and cell wall-bound phenolic acids (especially ferulic acid) started to increase (relative to controls) within 4 h after the addition of the WF preparation and remained high in elicited cells for 8–12 h. A moderate increase in phenolic acids in cells exposed to the PF preparation was observed within 8 h after application. However, after 24 h of WF treatment a decline of total phenolics was observed, while in PF elicited Norway spruce cells the phenolic content continued to increase. Significantly decreased concentrations of stilbene glycosides, isorhapontin, astringin and piceid, were determined in PF and WF treated Norway spruce cell cultures. The total content of stilbene glycosides decreased within 8 h after WF application to 68% of the amount determined in the control and within 12 h to 73% of the control in PF-treated cells. These results demonstrate that both PF and WF prepared from the Sirococcus strobilinus mycelium elicit changes in the metabolism of phenylpropanoids, which are involved in the defence responses of plants to pathogens.

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