Histopathology of infection of bean with Pythium myriotylum compared with infection with other Pythium species

1975 ◽  
Vol 53 (17) ◽  
pp. 1786-1795 ◽  
Author(s):  
Roberta L. Dow ◽  
Robert D. Lumsden
Keyword(s):  
Cell Walls ◽  
Vascular Tissue ◽  
Tap Water ◽  
Pythium Ultimum ◽  
Epidermal Cells ◽  
Pythium Species ◽  
Pythium Myriotylum ◽  
Zoospore Production ◽  
Aerial Hyphae ◽  
Small Clusters

Clusters of abundant appressoria formed from branching hyphae of mycelial inoculum of Pythium myriotylum on the surface of bean hypocotyls and roots. Pythium aphanidermatum usually produced single appressoria, but sometimes small clusters of appressoria. Pythium ultimum produced only single appressoria. Early pathogenesis of all species was characterized by rapid radial growth of hyphae in the epidermal cells, which was more rapid than in the cortex. These hyphae were constricted at the host cell walls. Invaded tissue and adjacent cells stained differently from healthy cells with all isolates. Aerial hyphae were produced from vesicles below the cuticle or within epidermal cells soon after infection was established. Safranin-staining materials were observed in the xylem, phloem, and tannin sacs. Zoospores of P. myriotylum and P. aphanidermatum germinated and produced long prepenetration hyphae, which branched and formed single appressoria. Oospores of P. myriotylum, P. aphanidermatum, and P. ultimum, after germination, produced branched hyphae and single appressoria. Penetration, rapid advance through epidermal cells, and ramification of cortical and vascular tissue were identical with those of mycelial inoculum. Sporangia of all three species formed intercellularly and intracellulary within 48 h and predominantly in the epidermis and upper cortex. Oogonia were produced intercellularly and intracellularly in 4 day s throughout the tissue, but mainly in the inner two thirds of the cortex. Sporangia of P. myriotylum and P. aphanidermatum in infected bean hypocotyls germinated within 3 h when flooded with tap water and produced zoospores within 6 h. When similar tissue was air-dried for 3 days or rapidly dried for 3 h. there was neither germination nor zoospore production.

Isolation and characterization of cell walls from the mesocarp of mature grape berries (Vitis vinifera)

2020 ◽  
Author(s):  
KJ Nunan ◽  
Ian Sims ◽  
A Bacic ◽  
SP Robinson ◽  
GB Fincher
Keyword(s):  
Vitis Vinifera ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Compositional Analysis ◽  
Water Soluble ◽  
Vitis Vinifera L ◽  
Nylon Mesh ◽  
Cytoplasmic Material ◽  
Isolation And Characterization ◽  
Tissue Homogenates

Cell walls have been isolated from the mesocarp of mature grape (Vitis vinifera L.) berries. Tissue homogenates were suspended in 80% (v/v) ethanol to minimise the loss of water-soluble wall components and wet-sieved on nylon mesh to remove cytoplasmic material. The cell wall fragments retained on the sieve were subsequently treated with buffered phenol at pH 7.0, to inactivate any wall-bound enzymes and to dislodge small amounts of cytoplasmic proteins that adhered to the walls. Finally, the wall preparation was washed with chloroform/methanol (1:1, v/v) to remove lipids and dried by solvent exchange. Scanning electron microscopy showed that the wall preparation was essentially free of vascular tissue and adventitious protein of cytoplasmic origin. Compositional analysis showed that the walls consisted of approximately 90% by weight of polysaccharide and less than 10% protein. The protein component of the walls was shown to be rich in arginine and hydroxyproline residues. Cellulose and polygalacturonans were the major constituents, and each accounted for 30-40% by weight of the polysaccharide component of the walls. Substantial varietal differences were observed in the relative abundance of these two polysaccharides. Xyloglucans constituted approximately 10% of the polysaccharide fraction and the remainder was made up of smaller amounts of mannans, heteroxylans, arabinans and galactans.

The morphology of grain abscission in Zizania aquatica

1980 ◽  
Vol 58 (21) ◽  
pp. 2269-2273 ◽  
Author(s):  
H. B. Hanten ◽  
G. E. Ahlgren ◽  
J. B. Carlson
Keyword(s):  
Wild Rice ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Embryo Sac ◽  
Middle Lamella ◽  
Abscission Zone ◽  
Rice Grains ◽  
Zizania Aquatica ◽  
Parenchyma Cells ◽  
Anatomical Evidence

The anatomical development of the abscission zone in grains of Zizania aquatica L. was correlated with development of the embryo. The abscission zone is well developed when the embryo sac is mature. Soon after pollination, the first anatomical evidence of abscission appears as plasmolysis of the separation layer parenchyma cells. This is followed by separation of the layers by dissolution of the middle lamella and fragmentation of cell walls. Persistence of intact vascular tissue and presence of a surrounding cone-shaped mass of lignified cells may be involved in abscission of wild rice grains.

Conversaziones 1974

1975 ◽  
Vol 29 (2) ◽  
pp. 163-171
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Cell Walls ◽  
Structural Changes ◽  
Vascular Tissue ◽  
Root Systems ◽  
Plant Roots ◽  
Tracer Studies ◽  
Water Move ◽  
Intact Root

CONVERSAZIONES were held this year on 9 May and 27 June. At the first conversazione twenty-seven exhibits and two films were shown. The fine structure of plant roots in relation to transport of nutrient ions and water was demonstrated by Dr D. T. Clarkson of the A.R.C. Letcombe Laboratory, Wantage and Dr A. W. Robards of the Department of Biology, University of York. Two major pathways by which nutrients and water move radially across the cortex towards the central vascular tissue have been distinguished by the use of tracer studies of adsorption by different zones of intact root systems, microautoradiography and electron microscopy. Movement can be apoplastic through cell walls, or symplastic between cells joined by plasmodesmata. As the root ages, structural changes in the endodermis reduce movement in the former pathway but the symplast is not interrupted by the elaboration of endodermal walls because plasmodesmatal connexions remain intact. These observations help explain the contrasting extent to which different ions and water reach the shoot from young and mature parts of root systems.

The epidermis in Passerina/ (Thymelaeaceae): structure, function and taxonomic significance

Bothalia ◽  
2000 ◽  
Vol 30 (1) ◽  
pp. 69-86 ◽  
Author(s):  
C. L. Bredenkamp ◽  
A. E. Van Wyk
Keyword(s):  
Cell Walls ◽  
Mediterranean Climate ◽  
High Light Intensity ◽  
Epidermal Cells ◽  
Cell Orientation ◽  
Abaxial Surface ◽  
Epidermal Structure ◽  
Interspecific Differences ◽  
Epidermal Features ◽  
Structural Adaptations

Epidermal features were studied in all 17 species of Passerina, a genus endemic to southern Africa. Leaves in Passerina are inversely ericoid, the adaxial surface concave and the abaxial surface convex. Leaves are inversely dorsiventral and epistomatic. The adaxial epidermis is villous, with unicellular, uniseriate trichomes and relatively small thin-walled cells, promoting flexibility of leaf margins owing to turgor changes. In common with many other Thymelaeaceae, abaxial epidermal cells are large and tanniniferous with mucilaginous cell walls. The cuticle is adaxially thin, but abaxially well devel­oped, probably enabling the leaf to restrict water loss and to tolerate high light intensity and UV-B radiation. Epicuticular waxes, present in all species, comprise both soft and plate waxes. Epidermal structure proves to be taxonomically impor­tant at family, genus and species levels. Interspecific differences include arrangement of stomata and presence or absence of abaxial epidermal hair. Other diagnostic characters of the abaxial epidermal cells are arrangement,size and shape, cutic- ular ornamentation and presence or absence of wax platelets. Two groups of species on the basis of abaxial epidermal cell orientation are recognised. Many leaf epidermal features in Passerina are interpreted as structural adaptations to the Mediterranean climate of the Cape.

A new species and comparative morphology of Vesselowskya (Cunoniaceae)

2001 ◽  
Vol 14 (2) ◽  
pp. 175 ◽  
Author(s):  
Andrew C. Rozefelds ◽  
Richard W. Barnes ◽  
Belinda Pellow
Keyword(s):  
New Species ◽  
Cell Walls ◽  
New South ◽  
Comparative Morphology ◽  
Epidermal Cells ◽  
The Other ◽  
Abaxial Surface ◽  
South Wales ◽  
Central Column ◽  
A New Species

The vegetative and reproductive morphology of Vesselowskya Pampanini, southern marara, is described and illustrated in detail. The variation within V. rubifolia (F.Muell.) Pampanini sens. lat. is shown to be greater than has previously been recognised, with the differences identified supporting the recognition of a new segregate species, V. venusta Rozefelds, R.W.Barnes and Pellow sp. nov. Vesselowskya venusta occurs in the Barrington Tops Plateau of New South Wales and differs from V. rubifolia in possessing hairs on the abaxial surface of the sepals and lacking both a prominent distal connective protrusion on the anthers and colleters at the base of the stipules. The two Vesselowskya species are dioecious with a vestigial ovary in staminate flowers and reduced stamens in pistillate flowers. Dioecy is more pronounced in Vesselowskya, than in some Weinmannia species, and in both genera is expressed through reduction in the size of the ovaries in staminate flowers, and stamens in pistillate flowers. Vesselowskya shares with the other genera in the tribe Cunonieae (Pancheria, Weinmannia and Cunonia), a central column in the fruits, and Cunonia-type stipules, but differs from these genera in having valvate aestivation, digitate leaves, craspedodromous secondary venation with secondary veins terminating at a tooth, tuft domatia along the midrib, adaxial epidermal cells with strongly sinuous cell walls and the absence of hydathodes.

Comparison of photosynthetic carbon reduction (Kranz) cells having different ontogenetic origins in the C4 NADP – malic enzyme grass Arundinella hirta

1990 ◽  
Vol 68 (6) ◽  
pp. 1222-1232 ◽  
Author(s):  
Nancy G. Dengler ◽  
Ronald E. Dengler ◽  
Douglas J. Grenville
Keyword(s):  
Cell Walls ◽  
Vascular Tissue ◽  
Cell Types ◽  
Bundle Sheath ◽  
Carbon Reduction ◽  
Bundle Sheath Cells ◽  
Photosynthetic Carbon ◽  
Arundinella Hirta ◽  
Photosynthetic Carbon Reduction ◽  
Sheath Cells

The C4 grass Arundinella hirta is characterized by unusual leaf blade anatomy: photosynthetic carbon reduction takes place both within the chlorenchymatous bundle sheath cells of the longitudinal veins and within longitudinal strands of "distinctive cells" that form part of the leaf mesophyll and are often completely isolated from vascular tissue. Although they are equivalent physiologically, these two cell types have different ontogenetic origins: bundle sheath cells are delimited from procambium early in leaf development, whereas distinctive cells differentiate from ground meristem at a later developmental stage. Although the two cell types share numerous cytological features (large chloroplasts with reduced grana, thick cell walls with a suberin lamella), we also found significant differences in cell lengths, length to width ratios, cell cross-sectional areas, organelle numbers per cell cross section, phenol content of the cell walls, and numbers of pit fields in the longitudinal cell walls. The size and shape of bundle sheath cells are likely a direct consequence of procambial origin. The thicker walls of bundle sheath cells (in major veins) and their greater lignification may reflect the inductive effect of cell differentiation in the proximity of sclerenchyma and vascular tissues. Differences between major and minor vein bundle sheath cells may reflect differences in the timing of initiation of procambial strands. Our analysis of cell wall characteristics has also shown the presence of numerous primary pit fields in the transverse walls between adjacent distinctive cells in a file; plasmodesmata in these pit fields form a pathway for longitudinal symplastic transport not previously known to exist.

Parasitism of oospores of Pythium spp. by strains of Actinoplanes spp.

1993 ◽  
Vol 39 (10) ◽  
pp. 964-972 ◽  
Author(s):  
N. I. Khan ◽  
A. B. Filonow ◽  
L. L. Singleton ◽  
M. E. Payton
Keyword(s):  
Biological Control ◽  
Host Specificity ◽  
Pythium Ultimum ◽  
Pythium Myriotylum ◽  
Pythium Irregulare ◽  
Pythium Arrhenomanes ◽  
Parasite Specificity ◽  
Host Parasite ◽  
First Time

Strains of Actinoplanes spp. were evaluated for their in vitro parasitism of oospores of Pythium aphanidermatum, Pythium arrhenomanes, Pythium irregulare, Pythium myriotylum, and Pythium ultimum. Oospores of Pythium arrhenomanes, Pythium irregulare, and Pythium myriotylum were identified for the first time as hosts of Actinoplanes spp. Newly recorded parasites of oospores of Pythium spp. were Actinoplanes azureus, Actinoplanes brasiliensis, Actinoplanes caeruleus, Actinoplanes ferrugineus, Actinoplanes ianthinogenes, Actinoplanes italicus, Actinoplanes minutisporangius, Actinoplanes rectilineatus, Actinoplanes teichomyceticus, Actinoplanes utahensis, Actinoplanes violaceous, Actinoplanes yunnahenis, plus 15 strains of Actinoplanes yet to be speciated. Parasitized oospores had disorganized cytoplasms and hyphae of Actinoplanes sp. emerging from them. Infection of oospores in vitro varied from 0 to > 90%. Strains also were very active parasites of oospores in sterile soils. When added to nonsterile soils, several strains increased (p = 0.05) the level of oospore parasitism compared with nonsupplemented soils. Strains of Actinoplanes spp. exhibited a host specificity for species of Pythium in vitro and in soil. Sporulation of Actinoplanes sp. from infected oospores incubated on soil was frequent and more abundant than that observed in vitro.Key words: Pythium spp., Actinoplanes spp., actinomycetes, biological control, host–parasite specificity.

scholarly journals Detection of Pythium ultimum Using Polymerase Chain Reaction with Species-Specific Primers

Plant Disease ◽  
1997 ◽  
Vol 81 (10) ◽  
pp. 1155-1160 ◽  
Author(s):  
K. Kageyama ◽  
A. Ohyama ◽  
M. Hyakumachi
Keyword(s):  
Polymerase Chain Reaction ◽  
Internal Transcribed Spacer ◽  
Pcr Amplification ◽  
Its Region ◽  
Pythium Ultimum ◽  
Pythium Species ◽  
Chain Reaction ◽  
Specific Primers ◽  
Polymerase Chain ◽  
Species Specific

This study was conducted to sequence the rDNA internal transcribed spacer (ITS) region of Pythium ultimum and Pythium group HS, design species-specific primers for polymerase chain reaction (PCR), and detect P. ultimum from diseased seedlings using PCR. The sequence of the ITS region of P. ultimum was identical with that of Pythium group HS. The results support the reports that the HS group is an asexual strain of P. ultimum. Using PCR, the primer pair K1+K3, designed on portions of the sequence of the ITS region, amplified isolates of P. ultimum and the HS group but not isolates of 20 other Pythium species. DNA extracts from damped-off seedlings were not amplified, but a 10-fold dilution of the extracts with Tris-EDTA (TE) buffer diluted the inhibitors and allowed PCR amplification. The primer pair used detected P. ultimum from a single diseased seedling.

Penetration and colonization of resistant and susceptible Apium graveolens by Fusarium oxysporum f.sp. apii race 2: callose as a structural response

1988 ◽  
Vol 66 (12) ◽  
pp. 2385-2391 ◽  
Author(s):  
C. M. Jordan ◽  
R. M. Endo ◽  
L. S. Jordan
Keyword(s):  
Fusarium Oxysporum ◽  
Host Cell ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Periodic Acid ◽  
Light And Electron Microscopy ◽  
Structural Response ◽  
Aniline Blue ◽  
Apium Graveolens ◽  
Race 2

Root apices of Apium graveolens L. resistant and susceptible to race 2 of Fusarium oxysporum f.sp. apii (R. Nels. & Sherb.) were studied at various times after inoculation, using light and electron microscopy to determine structural response(s) of the hosts during penetration and colonization by the pathogen. Penetration was intercellular and intracellular and involved mechanical and enzymatic mechanisms. At the onset of penetration, the host cell walls manifested fluorescence, induced with either aniline blue or sirofluor, at the point of penetration. The fluorescent area was more intense and larger in the resistant host. Fluorescence disappeared with time. After incubation with β-1,3 glucanase fluorescence disappeared, indicating β-1,3 polysaccharide (probably callose) presence. Callose deposits were 2 and 3 times greater in the epidermis and 4 and 9 times greater in the cortex of the resistant than in two susceptible hosts, respectively. Hyphal counts in the cortex of the resistant host were 50% fewer than in the susceptible hosts. Increased callose deposition on host cell walls was associated with reduced colonization. Callose formed in vascular tissue as the fungus colonized it. Callose detection with sirofluor was more sensitive; background fluorescence common with aniline blue without periodic acid – Schiff's reagent pretreatment was absent.

Calcium Enhanced Zoospore Production of Pythium myriotylum in vitro

2002 ◽  
Vol 150 (7) ◽  
pp. 396-398 ◽  
Author(s):  
L. M. Nyochembeng ◽  
R. P. Pacumbaba ◽  
Caula A. Beyl
Keyword(s):  
Pythium Myriotylum ◽  
Zoospore Production
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