Association of epidermal lignification with nonhost resistance of cucurbits to fungi

1985 ◽  
Vol 63 (12) ◽  
pp. 2393-2398 ◽  
Author(s):  
Raymond Hammerschmidt ◽  
Alice M. Bonnen ◽  
Gary C. Bergstrom ◽  
Karen K. Baker
Keyword(s):  
Epidermal Cell ◽  
Cell Walls ◽  
Cupric Oxide ◽  
Histochemical Staining ◽  
The Other ◽  
Host Cells ◽  
Nonhost Resistance ◽  
Resistance Response ◽  
Etiolated Seedlings ◽  
Race 1

Etiolated seedlings of cucumber, muskmelon, watermelon, pumpkin, and squash were inoculated with Colletotrichum lagenarium (Pass.) Ell. & Halst. race 1, Colletotrichum atramentarium (Berk. & Br.) Taub., or Helminthosporium carbonum Ull. The fungi germinated and produced appressoria equally well on all hosts. Penetrations into host cells, however, were routinely observed only in the interactions of C. lagenarium with cucumber, muskmelon, and watermelon. Histochemical staining of the other host–pathogen interactions (nonhost interactions) revealed that the lack of penetration by fungi into nonhost tissue was associated with the deposition of lignin in the upper and lateral host epidermal cell walls around appressoria. Treatment of the lignified tissues with 0.5 M NaOH or hot ethanol did not alter staining reactions. Treatment with hot aminoethanol, a delignifying agent, did eliminate stainings. Cupric oxide oxidation of lignified epidermal cell walls from each host revealed that each host produced a p-coumaryl-rich, guaiacyl-poor ligninlike material. These results suggest that lignification may be a general nonhost resistance response in the Cucurbitaceae.

scholarly journals Histology of Infection of Hydrilla verticillata by Macrophomina phaseolina

Weed Science ◽  
1992 ◽  
Vol 40 (2) ◽  
pp. 288-295 ◽  
Author(s):  
Gary F. Joye ◽  
Rex N. Paul
Keyword(s):  
Cell Wall ◽  
Host Cell ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Hydrilla Verticillata ◽  
Macrophomina Phaseolina ◽  
Host Cells ◽  
Outer Cell ◽  
Cell Wall Disruption ◽  
Outer Cell Wall

Infection of Hydrilla verticillata by Macrophomina phaseolina was investigated using scanning and transmission electron microscopy. Sprigs of plants in petri plates were inoculated with suspensions of fungal hyphae. Samples of inoculated and noninoculated plants were taken over time. Fungal cells attached to lower epidermal cell walls but not the upper epidermal cell walls of leaves. In less than 40 h, penetration through the cell wall was completed and colonization of host cells was observed. Penetration of upper epidermis was limited to the cell wall adjacent to a lower epidermal cell. No penetration was observed through the outer cell wall of upper epidermis. Inhibition of penetration through the outer cell wall of the upper epidermis may be attributable to an osmiophilic layer below the cell wall. Disruption of the host cell walls and subsequent host cell death was preceded by massive colonization of the host by this pathogen.

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

scholarly journals DISTRIBUTION AND RACE COMPOSITION OF DOWNY MILDEW (Plasmopara halstedii (Farl.) Berl. and de Toni) IN BULGARIA / EXTENSION Y RAZAS DEL MILDIU (Plasmopara halstedii (Farl.) Berl. y de Toni) EN BULGARIA / ÉTENDUE ET RACES DE LA ROUILLE (Plasmopara halstedii (Farl.) Berl. and de Toni) EN BULGARIE

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 25-32
Author(s):  
P.S. Shindrova
Keyword(s):  
Downy Mildew ◽  
Resistance Gene ◽  
The Other ◽  
Plasmopara Halstedii ◽  
North West ◽  
North East ◽  
Race 1 ◽  
Race 2 ◽  
Production Areas ◽  
Number Of Authors

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.

Etude ultrastructurale des relations hôte–parasite au cours de l'infection des pommes par le Phytophthora cactorum

1981 ◽  
Vol 59 (2) ◽  
pp. 251-263 ◽  
Author(s):  
X. Mourichon ◽  
G. Sallé
Keyword(s):  
Cell Walls ◽  
Susceptible Variety ◽  
Host Cells ◽  
Phytophthora Cactorum ◽  
Electron Microscopic ◽  
Susceptible Host ◽  
Golden Delicious ◽  
Extrahaustorial Matrix ◽  
Apple Fruits

An electron microscopic study was performed on haustoria of Phytophthora cactorum (L. et C.) Schroeter developed in tissues of two cultivars of apple fruits: a susceptible variety ('Golden delicious') and a resistant one ('Belle de Boskoop'). Ultrastructure of intercellular hyphae and some aspects of their penetration between contiguous host cells were described. A light dissolution of the host cell walls was observed. Ontogenic investigations indicated that in the susceptible host, the wall of the fungal haustoria was covered with a dense-stained extrahaustorial matrix. Its origin and its polysaccharide nature were demonstrated. On the other hand, the resistant host developed, immediately after the inoculation, a papilla which gave rise, later on, to a sheath enclosing adult haustoria. The role of these callosic structures in the phenomenon of resistance was discussed.

New Perspectives for SARS-CoV-2 Rapid Detection

Coronaviruses ◽  
2021 ◽  
Vol 02 ◽  
Author(s):  
Latifa Khattabi ◽  
Mustapha Mounir Bouhenna ◽  
Feriel Sellam
Keyword(s):  
Rapid Detection ◽  
High Sensitivity ◽  
The Other ◽  
Host Cells ◽  
Rt Pcr ◽  
Human Immune System ◽  
Virus Attachment ◽  
Testing Procedures ◽  
Diagnostic Kits ◽  
Human Immune

: The present paper elucidates the conceivable application of two key molecules in SARS-CoV-2 detection of suspected infected persons. These molecules were selected from the basis of ACE-2 and S protein strong interaction that allows virus attachment to its host cells, on the other hand specific immunocompetant effectors generated by human immune system during the infection. Several testing procedures are already used to diagnose SARS-CoV-2 infection, particularly RT-PCR technique. ELISA and LFIA are possible assays for the employment of shACE-2/ hAc-anti-S (the molecules of interest) as the main agents of the test and confer a dual principal functions (capture and detection). The future diagnostic kits involving shACE-2 and hAc-anti-S will have the particularity of high sensitivity and rapid detection in addition to its advantage of relatively easy conception. It could be largely considered as a technical advanced kits in regards to the current SARS-CoV-2 diagnostic immunoassays.

scholarly journals Pea–Fusarium solani Interactions Contributions of a System Toward Understanding Disease Resistance

2008 ◽  
Vol 98 (4) ◽  
pp. 372-379 ◽  
Author(s):  
Lee A. Hadwiger
Keyword(s):  
Immune Response ◽  
Transcription Factor ◽  
Disease Resistance ◽  
Fusarium Solani ◽  
Nonhost Resistance ◽  
Chromatin Conformation ◽  
Resistance Response ◽  
Resistance Components ◽  
Pathogenesis Related ◽  
Molecular Aspects

This mini-review points to the usefulness of the pea–Fusarium solani interaction in researching the biochemical and molecular aspects of the nonhost resistance components of peas. This interaction has been researched to evaluate the resistance roles of the phytoalexin, pisatin, the cuticle barrier, and the activation of the nonhost resistance response. Concurrently, evaluations of associated signaling processes and the tools possessed by the pathogen to contend with host obstacles were included. The properties of some pathogenesis-related genes of pea and their regulation and contribution to resistance are discussed. A proposed action of two biotic elicitors on both chromatin conformation and the architectural transcription factor, HMG A, is presented and includes time lines of events within the host immune response.

scholarly journals Anatomía de la semilla de Tigridia pavonia (Iridaceae)

2017 ◽  
pp. 66
Author(s):  
Aída Carrillo-Ocampo ◽  
E.M. Engleman
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Thin Layer ◽  
Cell Walls ◽  
Histochemical Staining ◽  
Stage Of Development ◽  
Scanning Electron

With methods of light microscopy, histochemical staining and scanning electron microscopy, it was found that the ovule in the seed of Tigridia pavonia (Iridaceae) is anatropous, bitegmic, and crassinucellate. During development, the exotegmen is crushed and the endotegmen persists with tannins in the lumens and in the walls, which also react positively for lignin. The exotesta contains tannins and its outer walls are convex, thickened, and cuticularized. The mesotesta has multiple layers, accumulates abundant lipids, and forms a bulge in the chalaza. The cell walls of the endotesta collapse and accumulate tannins. In the chalaza, a hypostasal cushion contains tannins in the lumens and in the walls, which also react positively for lignin. At the micropylar end of the seed there is an operculum which consists of: a) a slightly crushed exotegmen, b) an endotegmen with cuticular thickenings that are concentric with respect to the micropyle, c) hemispherical deposists of cutin on the anticlinal walls of the endotegmen, and c) a thin layer of endosperm that covers the radicle. During its cellular stage of development, the endosperm has conspicuous transfer walls at the chalazal end next to the nucella. The embryo is small and has a conical cotyledon.

scholarly journals Processes in the Infection of Barley Leaves by Rhynchosporium Secalis

1970 ◽  
Vol 23 (2) ◽  
pp. 300 ◽  
Author(s):  
EN AYESU-OFFEI ◽  
BG CLARE
Keyword(s):  
Epidermal Cell ◽  
Cell Walls ◽  
Rhynchosporium Secalis ◽  
Barley Leaves ◽  
Germ Tubes

Conidia of R. secalis (Oud.) Davis germinated on barley leaves to produoe , short germ tubes and appressoria. Hyphae below the appressoria penetrated the outicle and formed extensive myoelial mats between the cuticle and the outer epidermal cell walls. Epidermal cell walls beneath the subcuticular hyphae became swollen, lamellate, and collapsed so that the inner and outer walls of the epidermis came together.

Über die quantitative Verteilung der Ascorbinsäure innerhalb der Pflanzenzelle

1964 ◽  
Vol 19 (12) ◽  
pp. 1146-1149 ◽  
Author(s):  
Wolfgang Franke ◽  
Ulrich Heber
Keyword(s):  
Ascorbic Acid ◽  
Acid Content ◽  
Cell Walls ◽  
Direct Evidence ◽  
Ascorbic Acid Content ◽  
The Other ◽  
Leaf Cell ◽  
Unequal Distribution ◽  
Freeze Dried ◽  
High Figure

Leaves, which had been killed in liquid air, were freeze dried and then fractionated by a nonaqueous method. Two fractions were obtained, one consisting of chloroplasts and the other of cytoplasm, vacuolar constituents, cell walls and residual chloroplasts. Calculation of the intracellular distribution of ascorbic acid based on the analysis of the two fractions revealed that 40 to 50% of the total ascorbic acid content of the cells is located within the chloroplasts. Since chloroplasts occupy less than 10% of the total volume of the cells, this high figure is direct evidence of an unequal distribution of ascorbic acid within the leaf cell.

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