Development of Cronartium comandrae in Comandra umbellata

1973 ◽  
Vol 51 (7) ◽  
pp. 1369-1372
Author(s):  
F. H. Tainter
Keyword(s):  
Rust Fungus ◽  
Central Core ◽  
Host Cells ◽  
Fungal Mycelium ◽  
Basal Cells ◽  
Intercellular Spaces ◽  
Mesophyll Cells

Infection of bastard toadflax by aeciospores of the comandra rust fungus appeared to occur through stomata. Within 3–4 days substomatal hyphae began ramifying into intercellular spaces between mesophyll cells. On the 5th day small chlorotic spots were visible with a 10 × hand lens and within 9 days, yellow uredial pustules were visible to the unaided eye. Uredia maturation proceeded via a palisade-like arrangement of cells to form basal cells, uredial initials, stalk cells, and urediospores, successively. By the 5th day haustoria began forming and by the 9th day were numerous, developing into a variety of sizes and shapes. Several layers of immature urediospores were also produced. By the 20th day host mesophyll cells became slightly compacted in the vicinity of the pustule and intercellular spaces were packed with fungal mycelium. After 25 days, the host cells in the base of the pustule became visibly disorganized and a central core of hyphae had developed in the base of most pustules, severely misshaping some host cells. Between 25 and 28 days most pustule membranes had ruptured and urediospores were liberated. Telia began to form in the former uredia by the 32nd day after inoculation.

THE PHYSIOLOGY OF HOST–PARASITE RELATIONS: XVIII. DISTRIBUTION OF TRITIUM-LABELLED CYTIDINE, URIDINE, AND LEUCINE IN WHEAT LEAVES INFECTED WITH THE STEM RUST FUNGUS

1967 ◽  
Vol 45 (5) ◽  
pp. 555-563 ◽  
Author(s):  
P. K. Bhattacharya ◽  
Michael Shaw
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Host Cells ◽  
Fungal Mycelium ◽  
Puccinia Graminis ◽  
Mesophyll Cells ◽  
Wheat Leaves ◽  
Host Parasite

Wheat leaves were detached 6 days after inoculation with the stem rust fungus (Puccinia graminis var. tritici Erikss. and Henn.) and fed with tritiated leucine, cytidine, uridine, or thymidine. Mesophyll cells in infected zones incorporated more leucine into protein and more cytidine and uridine into RNA than did cells in adjacent uninfected tissue. Leucine, cytidine, and uridine were also heavily incorporated by fungal mycelium and developing uredospores. Grain counts over host nuclei in the infected zone were two to three-fold of those over nuclei in adjacent uninfected zones. There was no detectable incorporation of thymidinemethyl-3H into either the fungus or the host cells. The results are discussed.

scholarly journals Comparative Study on Gas Exchange, Water Relations and Leaf Anatomy of Two Olive Cultivars Grown under Well-Irrigated and Drought Conditions

1999 ◽  
Vol 54 (9-10) ◽  
pp. 688-692 ◽  
Author(s):  
Konstantinos Chartzoulakis ◽  
Angelos Patakas ◽  
Artemis Bosabalidis
Keyword(s):  
Gas Exchange ◽  
Water Relations ◽  
Volume Fraction ◽  
Spongy Parenchyma ◽  
Intercellular Spaces ◽  
Palisade Parenchyma ◽  
Mesophyll Cells ◽  
Olive Cultivars ◽  
Olea Europea ◽  
Leaf Anatomical Characteristics

The effect of water stress on gas exchange, water relations and leaf anatomical characteristics have been studied in two olive cultivars (Olea europea, L. cv. ‘Koroneiki’ and cv. ‚Mastoidis’). Photosynthetic rate as well as stomatal conductance were decreased in stressed plants. Osmotic potential (π) declined rapidly in stressed plants indicating their ability for osmoregulation. Bulk modulus of elasticity (ε) was significantly higher in stressed compared to well irrigated plants. The volume fraction of intercellular spaces of the upper palisade parenchyma, the spongy parenchyma as well as the lower palisade parenchyma were significantly lower in stressed compared to well irrigated plants. On the other hand, the density of mesophyll cells in the upper palisade parenchyma, spongy parenchyma and lower palisade parenchyma increased significantly in stressed plants

A light and electron microscope study of the fungal endophytes in the sporophyte and gametophyte of Lycopodium cernuum with observations on the gametophyte–sporophyte junction

1992 ◽  
Vol 70 (1) ◽  
pp. 58-72 ◽  
Author(s):  
Jeffrey G. Duckett ◽  
Roberto Ligrone
Keyword(s):  
Root Nodules ◽  
Fungal Endophytes ◽  
Fungal Endophyte ◽  
Peninsular Malaysia ◽  
Epidermal Cells ◽  
Host Cells ◽  
Wall Material ◽  
Intercellular Spaces ◽  
Host Cytoplasm ◽  
Fungal Associations

The ventral epidermal cells of the photosynthetic, surface-living gametophytes of Lycopodium cernuum, collected from moist shaded banks in Peninsular Malaysia, contain an aseptate fungus. In some cells the hyphae are thick walled and form coils encapsulated by a thin layer of host wall material. In others the fungus is thin walled and shows limited differentiation into larger trunk hyphae and arbuscules. The adjacent host cytoplasm, separated from the fungus by a granular interfacial matrix, contains numerous chloroplasts, mitochondria, and microtubules. The hyphae contact the substratum via the ventral walls of the epidermal cells and the rhizoids are free from infection. In the protocorm and root nodules, aseptate hyphae initially colonize mucilage-filled schizogenous intercellular spaces. Subsequent invasion of the host cells is associated with the development of massive overgrowths of host wall material. The fungal associations in L. cernuum share a mixture of attributes otherwise found in different angiosperm mycorrhizae and in mycotrophic relationships in liverworts. Wall ingrowths are present in both the gametophyte and sporophyte cells in the placenta of L. cernuum. The very limited development of the placenta, compared with L. appressum, certain bryophytes and ferns, the diminutive size, and early senescence of the gametophytes of L. cernuum are all linked to the presence of the protocorm. This massive absorptive organ, homologous to a foot, in terms of its position in sporophyte ontogeny, but external to the parent gametophyte, derives its nutrition partly from photosynthesis and partly from its fungal endophyte. Key words: chloroplasts, Lycopodium, mycorrhiza, pteridophytes, root nodules, symbiosis, transfer cells.

scholarly journals Structural genomic applied on the rust fungus Melampsora larici-populina reveals two candidate effector proteins adopting cystine-knot and nuclear transport factor 2-like protein folds

2019 ◽  
Author(s):  
Karine de Guillen ◽  
Cécile Lorrain ◽  
Pascale Tsan ◽  
Philippe Barthe ◽  
Benjamin Petre ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Nuclear Transport ◽  
Sequence Similarity ◽  
Rust Fungus ◽  
Parasitic Infection ◽  
Effector Proteins ◽  
Host Cells ◽  
Dimensional Structure ◽  
Structural Genomic ◽  
Transport Factor

ABSTRACTRust fungi are plant pathogens that secrete an arsenal of effector proteins interfering with plant functions and promoting parasitic infection. Effectors are often species-specific, evolve rapidly, and display low sequence similarities with known proteins or domains. How rust fungal effectors function in host cells remains elusive, and biochemical and structural approaches have been scarcely used to tackle this question. In this study, we used a strategy based on recombinant protein production in Escherichia coli to study eleven candidate effectors of the leaf rust fungus Melampsora larici-populina. We successfully purified and solved the three-dimensional structure of two proteins, MLP124266 and MLP124017, using NMR spectroscopy. Although both proteins show no sequence similarity with known proteins, they exhibit structural similarities to knottin and nuclear transport factor 2-like proteins, respectively. Altogether, our findings show that sequence-unrelated effectors can adopt folds similar to known proteins, and encourage the use of biochemical and structural approaches to functionally characterize rust effector candidates.

Non-host resistance responses of Arabidopsis thaliana to the coffee leaf rust fungus (Hemileia vastatrix)

Botany ◽  
2010 ◽  
Vol 88 (7) ◽  
pp. 621-629 ◽  
Author(s):  
Helena Gil Azinheira ◽  
Maria do Céu Silva ◽  
Pedro Talhinhas ◽  
Clara Medeira ◽  
Isabel Maia ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Leaf Rust ◽  
Rust Fungus ◽  
Hemileia Vastatrix ◽  
Callose Deposition ◽  
Mesophyll Cells ◽  
Model Plant ◽  
Heterologous System ◽  
Coffee Leaf Rust ◽  
Model Plant Arabidopsis Thaliana

Leaf rust, caused by Hemileia vastatrix Berk & Broome, is the most destructive fungal disease of coffee. In the absence of a suitable gene validation system in coffee, the objective of this study was to investigate whether the model plant Arabidopsis thaliana (L.) Heynh. may be used as a heterologous system for the molecular dissection of coffee responses to leaf rust. Histological examination of A. thaliana (Col-0) leaves inoculated with H. vastatrix (race II) showed that by 24 h after inoculation (hai), H. vastatrix uredospores differentiated appressoria and penetrated the stomata, but failed to form haustoria. Arabidopsis thaliana cellular resistance responses included hypersensitive-like response (HR) of stomata guard cells together with accumulation of phenolic compounds and callose deposition in walls of epidermal and mesophyll cells. Results indicate that H. vastatrix infection triggered the induction of a set of defence-related genes peaking at 18 and 42 hai. The non-host HR triggered by H. vastatrix in the model plant A. thaliana makes it usable to infer the function of coffee genes involved in pre-haustorial rust resistance.

scholarly journals Leaf Cuticle Can Contribute to Non-Host Resistance to Poplar Leaf Rust

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 870 ◽  
Author(s):  
Yu ◽  
Shen ◽  
Newcombe ◽  
Fan ◽  
Chen
Keyword(s):  
Host Resistance ◽  
Populus Deltoides ◽  
Rust Fungus ◽  
Trimethylsilyl Ether ◽  
Populus Tomentosa ◽  
Rust Fungi ◽  
Mesophyll Cells ◽  
Defense Compounds ◽  
Leaf Cuticle ◽  
Poplar Leaf

The plant leaf cuticle is a chemically complex but largely waxy outer shell that limits water loss and also prevents some pathogens from gaining access to internal mesophyll. Rust fungi are obligate parasites, and most bypass the cuticle by thigmotropically locating stomata, growing through the stomatal openings, and then parasitizing mesophyll cells with haustoria. It is thought that even non-hosts of a given rust fungus do not resist until their mesophyll cells are contacted in this way. In other words, it is thought that the cuticle plays no role in non-host resistance. Here, we tested the hypothesis that poplar leaf cuticles might contribute to non-host resistance to rust fungi by chemically impeding the germination and growth of urediniosporelings of Melampsora larici-populina. Following an initial survey in China of the resistance of 36 genotypes of various species and interspecific hybrids of Populus to M. larici-populina, we selected three genotypes for the initial test of hypothesis: (1) A Populus purdomii genotype that is fully susceptible; (2) a Populus deltoides cv. ‘I-69′ that is incompletely resistant (i.e., a resistant host); and (3) a Populus tomentosa genotype that is a non-host to M. larici-populina. Urediniospores were assayed for germination in extracts of the cuticles of the three genotypes. Germination was most reduced by the P. tomentosa non-host cuticular extracts that also reduced the growth of germ tubes to 36 times less than that in controls or in the extract of the susceptible P. purdomii. Four cuticular components were identified as putative defense compounds given greater concentrations in P. tomentosa than in P. purdomii: Aucubin, hexakis(trimethylsilyl) ether, catechol, 7,9-Di-tert-buty l-1-oxaspiro (4,5) deca-6, 9-diene-2,8-dione and trifluoroacetamide. These four compounds were then tested, and they reduced urediniospore germination and uredinial density in inoculations of normally susceptible P. purdomii with Melampsora larici-populina. Thus, the cuticle of P. tomentosa can contribute to pre-haustorial, non-host resistance to M. larici-populina.

scholarly journals Candidate Effector Proteins of the Rust Pathogen Melampsora larici-populina Target Diverse Plant Cell Compartments

2015 ◽  
Vol 28 (6) ◽  
pp. 689-700 ◽  
Author(s):  
Benjamin Petre ◽  
Diane G. O. Saunders ◽  
Jan Sklenar ◽  
Cécile Lorrain ◽  
Joe Win ◽  
...  
Keyword(s):  
Rust Fungus ◽  
Effector Proteins ◽  
Host Cells ◽  
Plant Proteins ◽  
In Planta ◽  
Biologically Relevant ◽  
Heterologous System ◽  
Biotrophic Pathogens ◽  
Small Set ◽  
Clone And Express

Rust fungi are devastating crop pathogens that deliver effector proteins into infected tissues to modulate plant functions and promote parasitic growth. The genome of the poplar leaf rust fungus Melampsora larici-populina revealed a large catalog of secreted proteins, some of which have been considered candidate effectors. Unraveling how these proteins function in host cells is a key to understanding pathogenicity mechanisms and developing resistant plants. In this study, we used an effectoromics pipeline to select, clone, and express 20 candidate effectors in Nicotiana benthamiana leaf cells to determine their subcellular localization and identify the plant proteins they interact with. Confocal microscopy revealed that six candidate effectors target the nucleus, nucleoli, chloroplasts, mitochondria, and discrete cellular bodies. We also used coimmunoprecipitation (coIP) and mass spectrometry to identify 606 N. benthamiana proteins that associate with the candidate effectors. Five candidate effectors specifically associated with a small set of plant proteins that may represent biologically relevant interactors. We confirmed the interaction between the candidate effector MLP124017 and TOPLESS-related protein 4 from poplar by in planta coIP. Altogether, our data enable us to validate effector proteins from M. larici-populina and reveal that these proteins may target multiple compartments and processes in plant cells. It also shows that N. benthamiana can be a powerful heterologous system to study effectors of obligate biotrophic pathogens.

scholarly journals Submikroskopische Untersuchungen am Basaliom des Hundes

1968 ◽  
Vol 5 (2) ◽  
pp. 174-185
Author(s):  
W. Drommer
Keyword(s):  
Basal Cell ◽  
Single Cells ◽  
Cell Tumor ◽  
Basal Cells ◽  
Sebaceous Glands ◽  
Intercellular Spaces ◽  
Different Types

Six basal cell tumors of dogs were studied electron microscopically. The ultrastructure of different types of basal cell tumor differs as to the number of tonofibrils, the finger-like cytoplasmic extensions, the width of the intercellular spaces, and the hyaloplasma. Hemidesmosomes were found in all tumors. One basal cell tumor contained single cells resembling sebaceous cells which indicates differentiation of basal cells into sebaceous glands. Furthermore, there are ultrastructural differences between the cells of the stratum germinativum and the basal cell tumor.

scholarly journals Identification of a Protein from Rust Fungi Transferred from Haustoria into Infected Plant Cells

2005 ◽  
Vol 18 (11) ◽  
pp. 1130-1139 ◽  
Author(s):  
Eric Kemen ◽  
Ariane C. Kemen ◽  
Maryam Rafiqi ◽  
Uta Hempel ◽  
Kurt Mendgen ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Polyclonal Antibodies ◽  
Rust Fungus ◽  
Infected Plant ◽  
Plant Cells ◽  
Host Cells ◽  
Nuclear Localization Signals ◽  
Uromyces Fabae ◽  
Host Cytoplasm ◽  
Functional Efficiency

The formation of haustoria is one of the hallmarks of the interaction of obligate biotrophic fungi with their host plants. In addition to their role in nutrient uptake, it is hypothesized that haustoria are actively involved in establishing and maintaining the biotrophic relationship. We have identified a 24.3-kDa protein that exhibited a very unusual allocation. Rust transferred protein 1 from Uromyces fabae (Uf-RTP1p) was not only detected in the host parasite interface, the extrahaustorial matrix, but also inside infected plant cells by immunofluorescence and electron microscopy. Uf-RTP1p does not exhibit any similarity to sequences currently listed in the public databases. However, we identified a homolog of Uf-RTP1p in the related rust fungus Uromyces striatus (Us-RTP1p). The localization of Uf-RTP1p and Us-RTP1p inside infected plant cells was confirmed, using four independently raised polyclonal antibodies. Depending on the developmental stage of haustoria, Uf-RTP1p was found in increasing amounts in host cells, including the host nucleus. Putative nuclear localization signals (NLS) were found in the predicted RTP1p sequences. However, functional efficiency could only be verified for the Uf-RTP1p NLS by means of green fluorescent protein fusions in transformed tobacco protoplasts. Western blot analysis indicated that Uf-RTP1p and Us-RTP1p most likely enter the host cell as N-glycosylated proteins. However, the mechanism by which they cross the extrahaustorial membrane and accumulate in the host cytoplasm is unknown. The localization of RTP1p suggests that it might play an important role in the maintenance of the biotrophic interaction.

Development of infection structures by Hemileia vastatrix in resistant and susceptible selections of Coffea and in Phaseolus vulgaris

1993 ◽  
Vol 71 (8) ◽  
pp. 1001-1008 ◽  
Author(s):  
T. A. Coutinho ◽  
F. H. J. Rijkenberg ◽  
M. A. J. van Asch
Keyword(s):  
Phaseolus Vulgaris ◽  
Primary Infection ◽  
Intercellular Spaces ◽  
Hemileia Vastatrix ◽  
Mesophyll Cells ◽  
Sequence Of Events ◽  
Successful Infection ◽  
Coffee Leaf Rust ◽  
Subsidiary Cells ◽  
Mother Cells

The sequence of events leading to successful infection of Coffea by Hemileia vastatrix, following the formation of an appressorium over a stoma, was investigated using scanning electron microscopy. In the host, Coffea arabica, a torpedoshaped substomatal vesicle initial develops bilaterally from the apex of the infection wedge, while in the nonhost, Phaseolus vulgaris, the infection wedge protrudes into the substomatal chamber. The substomatal vesicle in both host and nonhost, at 48 h postinoculation, is anchor shaped. Haustorial mother cells are formed on stubby primary infection hyphae that curve back onto subsidiary cells. No differences in appearance of these structures were noted between resistant and susceptible coffee selections. A much-branched mycelium ramifies through the intercellular spaces of the mesophyll cells 96 h postinoculation in the host. In bean, the SSV began to collapse 48 h postinoculation. Key words: coffee leaf rust, infection, penetration, Coffea, appressorium, substomatal vesicle.

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