Microscopy of Fusarium solani infected rough lemon citrus fibrous roots

1986 ◽  
Vol 64 (12) ◽  
pp. 2840-2847 ◽  
Author(s):  
S. Nemec ◽  
D. Stamper Achor ◽  
L. G. Albrigo
Keyword(s):  
Fusarium Solani ◽  
Cell Walls ◽  
Vessel Element ◽  
Primary Xylem ◽  
Root Hair Cell ◽  
Rough Lemon ◽  
Transmission Electron ◽  
Citrus Rootstock ◽  
Cortical Infection ◽  
Fibrous Roots

Mode of Fusarium solani penetration into rough lemon citrus rootstock seedling fibrous roots was determined and root symptomatology was evaluated using light, scanning, and transmission electron microscopy. Roots contained limited subepidermal infection 15 h after inoculation. Invasion of epidermal cells was principally through broken epidermal and root hair cell walls, but direct penetration also occurred. Cortical infection was primarily intracellular. Severe root rot was present 36–60 h after inoculation and in most cases infection after 60 h resulted in disruption of the phloem and endodermis around the still relatively intact primary xylem. Naturally infected roots from field trees were collected in an advanced stage of rot. In these, F. solani digestion of middle lamellae of primary xylem was common, and infection and erosion of secondary vessel element walls occurred frequently.

scholarly journals Sodium Distribution in Salt-stressed Citrus Rootstock Seedlings

HortScience ◽  
2012 ◽  
Vol 47 (10) ◽  
pp. 1504-1511 ◽  
Author(s):  
Pedro Gonzalez ◽  
James P. Syvertsen ◽  
Ed Etxeberria
Keyword(s):  
Cell Walls ◽  
Laser Scanning ◽  
Root Tissue ◽  
Confocal Laser ◽  
Specific Cell ◽  
Green Fluorescence ◽  
Rough Lemon ◽  
Leaf Chlorophyll ◽  
Citrus Rootstock ◽  
Swingle Citrumelo

Although citrus trees are considered relatively salt-sensitive, there are consistent differences in Na+ and Cl– tolerance among different citrus rootstocks. We grew uniform seedlings of rough lemon (RL) and the more Na+-tolerant Swingle citrumelo (SC) with and without 50 mm NaCl for 42 days. Salinity reduced leaf chlorophyll and plant transpiration rate (Ep) more in RL than SC. Confocal laser scanning analyses using the Na+-specific cell-permeant fluorescent probe CoroNa-Red revealed a higher capacity for Na+ sequestration in root tissue vacuoles of SC than in RL roots and that cell walls within the stele acted as Na+ traps. In leaves, however, RL had significantly higher Na+-dependent fluorescence than SC. Thus, the sequestration of Na+ in root tissue vacuoles and its immobilization by cell walls were key contributing mechanisms enabling SC leaves to maintain lower levels of Na+ than RL leaves. Examination of intracellular distribution of CoroNa-Green fluorescence in SC root protoplasts verified a vacuolar localization for Na+ in addition to the presence of a 2- to 6-μm unidentified endosomal compartment containing significantly higher Na+ concentrations.

NITROGEN NUTRITION OF CITRUS NURSERY STOCK IN PINE BARK SUBSTRATES.

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1161f-1161
Author(s):  
John D. Lea-Cox ◽  
Irwin E. Smith
Keyword(s):  
Nutrient Solution ◽  
Nitrogen Nutrition ◽  
Dry Mass ◽  
Pine Bark ◽  
Growing Period ◽  
Rough Lemon ◽  
Nursery Stock ◽  
Citrus Rootstock ◽  
Cleopatra Mandarin ◽  
Nutrient Solutions

Pine bark is utilized as a substrate in citrus nurseries in South Africa. The Nitrogen (N) content of pine bark is inherently low, and due to the volubility of N, must be supplied on a continual basis to ensure optimum growth rates of young citrus nursery stock. Three citrus rootstock (rough lemon, carrizo citrange and cleopatra mandarin) showed no difference in stem diameter or total dry mass (TDM) when supplied N at concentrations between 25 and 200 mg ·l-1 N in the nutrient solution over a 12 month growing period. Free leaf arginine increased when N was supplied at 400 mg·l-1 N. The form of N affected the growth of rough lemon. High NH4-N:NO3-N (75:25) ratios decreased TDM when Sulfur (S) was absent from the nutrient solution, but not if S was present. Free arginine increased in leaves at high NH4-N (No S) ratios, but not at high NH4-N (S supplied) ratios. Free leaf arginine was correlated with free leaf ammonia. These results have important implications for reducing the concentration of N in nutrient solutions used in citrus nurseries and may indicate that higher NH4-N ratios can be used when adequate S is also supplied.

Ultrastructure of commercial recycled pulp fibers for the production of packaging paper

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 675-680 ◽  
Author(s):  
Jonas Brändström ◽  
Jean-Paul Joseleau ◽  
Alain Cochaux ◽  
Nathalie Giraud-Telme ◽  
Katia Ruel
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Significant Proportion ◽  
Pulp Fibers ◽  
Chemical Pulp ◽  
Recycled Pulp ◽  
Transmission Electron ◽  
Large Heterogeneity ◽  
Recycled Fibers ◽  
Packaging Paper

Abstract Transmission electron microscopy was used to investigate the ultrastructure of recycled pulp fibers originating from a household collection plant and intended for the production of packaging paper. Three recovered paper grades and recycling processes, including pulping, screening, cleaning and refining, were assessed with emphasis on surface and internal fibrillation as well as xylan localization. Results showed a large heterogeneity with respect to fiber ultrastructure within and between the grades. Screening and cleaning steps had no detectable effects, but refining clearly increased cell-wall delamination and surface fibrillation. Immunolabeling of xylans showed that they were distributed rather evenly across the cell walls. They were also present on fines. Two different mechanisms for fiber delamination and surface fibrillation were found, one which implies that internal and external fibrillation take place simultaneously across the cell wall, and another which implies successive peeling of layers or sub-layers from the outside towards the inside. It is suggested that recycled fibers of chemical pulp origin undergo the former mechanism and recycled fibers that contain lignin binding the cell wall matrix give rise to the latter peeling mechanism. Because several recycled fibers were severely delaminated and almost fractured, we suggest that to produce a good packaging paper, it is important that recycled pulp should contain a significant proportion of fibers with high intrinsic strength.

scholarly journals Characterization of Passage-Selected Vancomycin-Resistant Staphylococcus aureus Strains of Diverse Parental Backgrounds

2000 ◽  
Vol 44 (2) ◽  
pp. 294-303 ◽  
Author(s):  
Richard F. Pfeltz ◽  
Vineet K. Singh ◽  
Jennifer L. Schmidt ◽  
Michael A. Batten ◽  
Christopher S. Baranyk ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Walls ◽  
Methicillin Resistance ◽  
Surface Hydrophobicity ◽  
Whole Cell ◽  
Transmission Electron ◽  
Vancomycin Mics ◽  
Vancomycin Resistant ◽  
Doubling Times

ABSTRACT A series of 12 Staphylococcus aureus strains of various genetic backgrounds, methicillin resistance levels, and autolytic activities were subjected to selection for the glycopeptide-intermediate S. aureus (GISA) susceptibility phenotype on increasing concentrations of vancomycin. Six strains acquired the phenotype rapidly, two did so slowly, and four failed to do so. The vancomycin MICs for the GISA strains ranged from 4 to 16 μg/ml, were stable to 20 nonselective passages, and expressed resistance homogeneously. Neither ease of acquisition of the GISA phenotype nor the MIC attained correlated with methicillin resistance hetero- versus homogeneity or autolytic deficiency or sufficiency. Oxacillin MICs were generally unchanged between parent and GISA strains, although the mec members of both isogenic methicillin-susceptible and methicillin-resistant pairs acquired the GISA phenotype more rapidly and to higher MICs than did their susceptible counterparts. Transmission electron microscopy revealed that the GISA strains appeared normal in the absence of vancomycin but had thickened and diffuse cell walls when grown with vancomycin at one-half the MIC. Common features among GISAs were reduced doubling times, decreased lysostaphin susceptibilities, and reduced whole-cell and zymographic autolytic activities in the absence of vancomycin. This, with surface hydrophobicity differences, indicated that even in the absence of vancomycin the GISA cell walls differed from those of the parents. Autolytic activities were further reduced by the inclusion of vancomycin in whole-cell and zymographic studies. The six least vancomycin-susceptible GISA strains exhibited an increased capacity to remove vancomycin from the medium versus their parent lines. This study suggests that while some elements of the GISA phenotype are strain specific, many are common to the phenotype although their expression is influenced by genetic background. GISA strains with similar glycopeptide MICs may express individual components of the phenotype to different extents.

Root hair deformation in the infection process of Alnus rubra

1983 ◽  
Vol 61 (11) ◽  
pp. 2863-2876 ◽  
Author(s):  
Alison M. Berry ◽  
John G. Torrey
Keyword(s):  
Root Hair ◽  
Cell Walls ◽  
Root Hairs ◽  
Infection Process ◽  
Alnus Rubra ◽  
Pseudomonas Cepacia ◽  
Developmental Studies ◽  
Experimental Conditions ◽  
Root Hair Cell ◽  
Root Hair Deformation

Structural and cell developmental studies of root hair deformation in Alnus rubra Bong. (Betulaceae) were carried out following inoculation with the soil pseudomonad Pseudomonas cepacia 85, alone or in concert with Frankia, and using axenically grown seedlings. Deformational changes can be observed in elongating root hairs within 2 h of inoculation with P. cepacia 85. These growing root hairs become branched or multilobed and highly modified from the single-tip growth of axenic root hairs. The cell walls of deformed hairs are histologically distinctive when stained with the fluorochrome acridine orange. Filtrate studies using P. cepacia 85 suggest that the deforming substance is not a low molecular weight compound. Root hair deformation and the associated wall histology are host specific in that Betula root hairs show none of these responses when grown and inoculated in the experimental conditions described. The bacterially induced changes in root hair cell walls during deformation may create a chemically and physically modified substrate for Frankia penetration, and the deformation itself may serve to entrap and enclose the filamentous organism, allowing wall dissolution and entry. Thus these events represent a complex host response as a precondition to successful nodulation.

scholarly journals Submicroscopical Features of Leaves of Xyris Species

2001 ◽  
Vol 44 (4) ◽  
pp. 405-410 ◽  
Author(s):  
Maria das Graças Sajo ◽  
Silvia Rodrigues Machado
Keyword(s):  
Electron Microscope ◽  
Cell Walls ◽  
Guard Cells ◽  
Leaf Ultrastructure ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Inner Surface ◽  
Stomatal Guard Cells ◽  
Adaptative Significance ◽  
Scanning Electron

The leaf ultrastructure of five Xyris species were examined using scanning electron microscope (SEM), transmission electron microscope (TEM) and histochemical methods. All studied leaves show some features in epidermis and mesophyll, which were of considerable adaptative significance to drought stress. Such features included the occurrence of a pectic layer on the stomatal guard cells and the presence of a network of pectic compounds in the cuticle. Pectic compunds were also in abundance in lamellated walls of the mesophyll cells and on the inner surface of the sclerified cell walls of the vascular bundle sheaths. There were also specialized chlorenchymatous "peg cells" in the mesophyll and drops of phenolic compounds inside the epidermal cells.

scholarly journals The Fungicide Tetramethylthiuram Disulfide Negatively Affects Plant Cell Walls, Infection Thread Walls, and Symbiosomes in Pea (Pisum sativum L.) Symbiotic Nodules

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1488
Author(s):  
Artemii P. Gorshkov ◽  
Anna V. Tsyganova ◽  
Maxim G. Vorobiev ◽  
Viktor E. Tsyganov
Keyword(s):  
Pisum Sativum ◽  
Cell Walls ◽  
Infection Thread ◽  
Nodule Development ◽  
Starch Accumulation ◽  
Ultrastructural Organization ◽  
Negative Effects ◽  
Tetramethylthiuram Disulfide ◽  
Transmission Electron ◽  
Nodule Senescence

In Russia, tetramethylthiuram disulfide (TMTD) is a fungicide widely used in the cultivation of legumes, including the pea (Pisum sativum). Application of TMTD can negatively affect nodulation; nevertheless, its effect on the histological and ultrastructural organization of nodules has not previously been investigated. In this study, the effect of TMTD at three concentrations (0.4, 4, and 8 g/kg) on nodule development in three pea genotypes (laboratory lines Sprint-2 and SGE, and cultivar ‘Finale’) was examined. In SGE, TMTD at 0.4 g/kg reduced the nodule number and shoot and root fresh weights. Treatment with TMTD at 8 g/kg changed the nodule color from pink to green, indicative of nodule senescence. Light and transmission electron microscopy analyses revealed negative effects of TMTD on nodule structure in each genotype. ‘Finale’ was the most sensitive cultivar to TMTD and Sprint-2 was the most tolerant. The negative effects of TMTD on nodules included the appearance of a senescence zone, starch accumulation, swelling of cell walls accompanied by a loss of electron density, thickening of the infection thread walls, symbiosome fusion, and bacteroid degradation. These results demonstrate how TMTD adversely affects nodules in the pea and will be useful for developing strategies to optimize fungicide use on legume crops.

Xyloglucan, galactomannan, glucuronoxylan, and rhamnogalacturonan I do not have identical structures in soybean root and root hair cell walls

Planta ◽  
2015 ◽  
Vol 242 (5) ◽  
pp. 1123-1138 ◽  
Author(s):  
Artur Muszyński ◽  
Malcolm A. O’Neill ◽  
Easwaran Ramasamy ◽  
Sivakumar Pattathil ◽  
Utku Avci ◽  
...  
Keyword(s):  
Hair Cell ◽  
Root Hair ◽  
Cell Walls ◽  
Soybean Root ◽  
Rhamnogalacturonan I ◽  
Root Hair Cell

Colonization of Sphagnum cells by Lyophyllum palustre

1985 ◽  
Vol 63 (4) ◽  
pp. 757-761 ◽  
Author(s):  
E. Untiedt ◽  
K. Müller
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Host Cell ◽  
Cell Walls ◽  
Transmission Electron ◽  
Scanning Electron

Lyophyllum palustre (Peck) Singer, a basidiomycete (Tricholomataceae) parasitizing Sphagnum, was examined for points of contact between hyphae and Sphagnum cells with the help of light microscopy, scanning electron microscopy, and transmission electron microscopy. Results indicate that the fungus attacks Sphagnum cells by penetrating cell walls and altering host cell protosplasm. In addition, the formation of additional partitioning cell walls in attacked living Sphagnum cells was observed.

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