Ultrastructure of teliospore germination and basidiospore formation in the rust fungus Gymnosporangium clavipes

1981 ◽  
Vol 59 (6) ◽  
pp. 1041-1049 ◽  
Author(s):  
Charles W. Mims
Keyword(s):  
Lipid Droplets ◽  
Germ Tube ◽  
Rust Fungus ◽  
Spore Wall ◽  
Pore Region ◽  
Synaptonemal Complexes ◽  
Germ Pore ◽  
Teliospore Germination ◽  
Cytoplasmic Vesicles ◽  
Prophase Nucleus

A mature teliospore of Gymnosporangium clavipes is two celled with a long pedicel. The spore wall appears multilayered and a germ pore region is present in the wall at each end of the teliospore. The cytoplasm of the spore is dense and packed with lipid droplets. A single, dense, prophase nucleus is present in each cell. Synaptonemal complexes were observed in younger spores but not in mature, germinable spores. The cytoplasm of a germinating spore appears less dense than that of a nongerminating spore. During germination a germ tube emerges from the germ pore region of each cell. Cytoplasmic vesicles are numerous in the tip of the rapidly elongating promycelium. The nucleus enters the promycelium and divides meiotically. Centripetally developing septa divide the promycelium into four uninucleate cells each of which gives rise to a sterigma at the tip of which a basidiospore initial develops. Cytoplasmic vesicles are prominent in the tip of the developing sterigma and in the basidiospore initial. Once the nucleus has entered the basidiospore initial it divides mitotically. During this time time a septum develops within the sterigma and the spore is delimited from the sterigma by the formation of a second septum at the base of the spore.

Fine structure of basidiospores of the cedar-apple rust fungus Gymnosporangium juniperi-virginianae

1977 ◽  
Vol 55 (9) ◽  
pp. 1057-1063 ◽  
Author(s):  
Charles W. Mims
Keyword(s):  
Fine Structure ◽  
Thin Layer ◽  
Lipid Droplets ◽  
Germ Tube ◽  
Rust Fungus ◽  
Spore Wall ◽  
Lipid Bodies ◽  
Pore Region ◽  
Hilar Region ◽  
Endoplasmic Reticula

Each basidiospore of Gymnosporangium juniperi-virginianae contains many ribosomes as well as lipid droplets, mitochondria, small vesicles, endoplasmic reticula, and structures thought to be microbodies. Mature spores are either uninucleate or binucleate although larger, tetranucleate spores were occasionally observed. The spore wall appears as a thin layer except around the hilar region where two layers are evident. Germination is almost always lateral although no germ pore region was noted in the wall. Vacuolation takes place during germination and lipid bodies disappear. The wall of the germ tube arising from the spore is continuous with that of the spore. A large number of vesicles is present in the germ tube. Basidiospores may also germinate by repetition.

Light and electron microscopy of teliospores and teliospore germination in the rust fungus Coleosporium ipomoeae

2005 ◽  
Vol 83 (5) ◽  
pp. 451-458 ◽  
Author(s):  
C W Mims ◽  
E A Richardson
Keyword(s):  
Electron Microscopy ◽  
Rust Fungus ◽  
Fungal Spores ◽  
Light And Electron Microscopy ◽  
Spore Wall ◽  
Morning Glory ◽  
Extracellular Material ◽  
Teliospore Germination ◽  
Transmission Electron ◽  
Ipomoea Coccinea

A combination of light, scanning, and transmission electron microscopy was used to examine teliospores and teliospore germination in the rust fungus Coleosporium ipomoeae (Schw.) Burrill, a parasite of the wild morning glory Ipomoea coccinea L. Telia developed on abaxial surfaces of infected leaves and appeared as orange, waxy crusts usually associated with uredinia. Mature teliospores were cylindrical to slightly clavate in shape and thin-walled. The presence of chitin in the spore wall was demonstrated using wheat germ agglutinin gold labeling. Teliospores were surrounded by an electron-dense extracellular material. Each spore possessed a large prominent nucleus containing synaptonemal complexes indicative of prophase I meiotic nuclei. Following hydration, the nucleus of each spore completed meiosis and the spore was divided into four uninucleate compartments by the formation of three transverse septa. Each compartment gave rise to a germ tube into which the nucleus and cytoplasm migrated. Germ tubes developed into long slender sterigmata that grew through the extracellular material within the telium to become exposed on the leaf surface. A basidiospore then developed at the tip of each sterigma. Once the nucleus moved from the sterigma into the spore, a septum formed to delimit the spore from the tip of the sterigma.Key words: fungal spores, transmission and scanning electron microscopy, high pressure freezing.

Surface structure of germinating Uromyces dianthi urediospores as observed by scanning electron microscope

1971 ◽  
Vol 49 (12) ◽  
pp. 2243-2244 ◽  
Author(s):  
D. R. Jones
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Surface Structure ◽  
Germ Tube ◽  
Spore Wall ◽  
Spore Surface ◽  
Germ Pore ◽  
Tube Emergence ◽  
Scanning Electron

Germ pore regions could not be located on the surface of Uromyces dianthi urediospores before germination. Germ tube emergence did not split the spore wall. Double spine features were observed on the spore surface.

Ultrastructure of freeze-substituted appressoria produced by aeciospore germlings of the rust fungus Arthuriomyces peckianus

1991 ◽  
Vol 69 (8) ◽  
pp. 1655-1665 ◽  
Author(s):  
E. C. Swann ◽  
C. W. Mims
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Key Words ◽  
Direct Contact ◽  
Germ Tube ◽  
Rust Fungus ◽  
Mitotic Division ◽  
Extracellular Material ◽  
Dialysis Membrane ◽  
Fungus Infection

Aeciospores of Arthuriomyces peckianus germinated readily on moist strips of dialysis membrane and developing appressoria were observed within 3 to 6 h after spores were deposited on membranes. A single germ tube typically emerged from each binucleate spore and grew until its tip contacted the dialysis membrane. The germ tube tip was then transformed into a swollen appressorium that adhered tightly to the membrane, apparently as a result of an extracellular material that surrounded the appressorium base. Virtually all the spore cytoplasm and both nuclei moved into the germ tube and developing appressorium. Following a synchronous mitotic division of the two nuclei, a septum formed to delimit the now tetranucleate appressorium from the germ tube. As the appressorium matured, an apparently wall-less region developed in the central portion of the appressorium appressed against the dialysis membrane. In this region the fungus plasma membrane appeared to make direct contact with the underlying dialysis membrane. A funnel-like or cone-like structure referred to as the appressorial cone then developed in the wall-less region. The appressorial cone extended up into the cytoplasm of the appressorium and was lined by the fungal plasma membrane. Numerous branched elaborations of the plasma membrane were associated with the inner portion of the cone. Key words: rust fungus, infection structures, electron microscopy.

Fruiting body development in the mycetozoan Echinostelium bisporum

1989 ◽  
Vol 67 (5) ◽  
pp. 1285-1293 ◽  
Author(s):  
Frederick W. Spiegel ◽  
Joyce Feldman
Keyword(s):  
Daughter Cell ◽  
Spore Wall ◽  
Microtubule Organizing Center ◽  
Free Living ◽  
Cell Stage ◽  
Synaptonemal Complexes ◽  
Body Development ◽  
Prespore Cell ◽  
Fruiting Body Development ◽  
Organizing Center

Fruiting was followed from the prespore cell stage through the appearance of synaptonemal complexes in the spores in the simple mycetozoan Echinostelium bisporum. The prespore cell differentiates from a uninucleate amoeboflagellate that rounds up on the surface of the substrate. Centrioles are present in the prespore cell. As the prespore cell continues to differentiate it secretes a sheath and becomes nearly spherical. The prespore cell begins to lay down the stalk within an invagination, then rises as a sporogen at the tip of the stalk. By the sporogen stage the centrioles disappear and a spherical microtubule organizing center (MTOC) appears between the nucleus and the stalk apex. At the end of stalk elongation, the nucleus undergoes an apparently closed acentric mitosis and the sporogen cleaves into two hemispheres. Each daughter cell then rounds up and begins to produce a sculptured spore wall. The nuclei of the spores enter presumed meiotic prophase with synaptonemal complexes after the spore wall is complete. The spherical MTOC is present in all stages after the sporogen. These characters suggest that E. bisporum is a reduced myxomycete that has lost the free living plasmoidal stage of the life cycle.

scholarly journals Fusion Body Formation, Germ Tube Anastomosis, and Nuclear Migration During the Germination of Urediniospores of the Wheat Leaf Rust Fungus, Puccinia triticina

2009 ◽  
Vol 99 (12) ◽  
pp. 1355-1364 ◽  
Author(s):  
Xiben Wang ◽  
Brent McCallum
Keyword(s):  
Leaf Rust ◽  
Germ Tube ◽  
Rust Fungus ◽  
Puccinia Triticina ◽  
Rust Fungi ◽  
Wheat Leaf Rust ◽  
Virulence Phenotype ◽  
Close Proximity ◽  
Wheat Leaf ◽  
Germ Tubes

Vegetative or parasexual recombination is thought to be a key mechanism for the genetic diversity of cereal rust fungi. The process of germ tube fusion leading to hyphal anastomosis and nuclear recombination was analyzed in wheat leaf rust fungus, Puccinia triticina. Germ tube anastomosis was observed in 27 P. triticina isolates, each representing a different virulence phenotype. Germ tube fusion bodies (GFBs), which appeared as viscid globules formed at tips of germ tubes, were essential for germ tube anastomosis. The formation of GFBs was affected by the urediniospore density and the length of illumination during germination. GFBs were formed at the highest frequency when urediniospores were spread to a concentration of 1 × 106 urediniospores/ml and incubated in dark for 12 to 24 h during germination. GFB attached to either the side of another germ tube (“tip to side”) or to another GFB formed at the tip of a second germ tube (“tip to tip”). In “tip to side” anastomosis, two nuclei in the germ tube bearing the GFB migrated into the second germ tube through the GFB which resulted in four nuclei within this germ tube. In “tip to tip” anastomosis, nuclei in both germ tubes migrated into the fused GFB and all four nuclei came into close proximity. Urediniospores of isolates MBDS-3-115 and TBBJ-5-11 were stained with DAPI (4′,6′diamine-2-phenylindole) and Nuclear Yellow (Hoechst S769121), respectively, and then mixed and germinated on water agar. Some fused GFBs contained nuclei stained with DAPI and nuclei stained with Nuclear Yellow in close proximity, demonstrating the fusion between genetically different P. triticina isolates. In some fused GFBs, “bridge-like” structures connecting different nuclei were observed.

Fine structure of sporangiole development in Choanephora cucurbitarum (Mucorales)

1982 ◽  
Vol 60 (11) ◽  
pp. 2313-2324 ◽  
Author(s):  
Michael T. Higham ◽  
Kathleen M. Cole
Keyword(s):  
Electron Microscopy ◽  
Germ Tube ◽  
Tube Wall ◽  
Outer Wall ◽  
Spore Wall ◽  
Wall Layer ◽  
Choanephora Cucurbitarum ◽  
Dark Staining ◽  
Granular Vesicles ◽  
Scanning Electron

Spore development was studied in Choanephora cucurbitarum by using transmission and scanning electron microscopy. Sporangioles are produced by expansion of the ampulla wall. A two-layered spore wall is then constructed within the spine-covered sporangiole wall. The outer spore wall layer is longitudinally grooved and is devoid of spines or appendages. The inner wall layer is thinner and electron transparent. During wall production, dark-staining granular vesicles were observed in the spore cytoplasm. Their contents stained similarly to the material of the outer wall layer. Mature spores possessed a third, innermost wall layer. This was identified as a new wall layer, which was continuous with the germ-tube wall of germinated spores. Released spores were observed to be contained within the sporangiole during dispersal and germination.

Ultrastructure of teliospore formation in the rust fungus Puccinia podophylli

1979 ◽  
Vol 57 (22) ◽  
pp. 2533-2538 ◽  
Author(s):  
Charles W. Mims ◽  
E. Laurence Thurston
Keyword(s):  
Rust Fungus ◽  
Ultrastructural Level ◽  
Spore Wall ◽  
Dense Layer ◽  
Spore Surface ◽  
Outer Electron ◽  
Cytoplasmic Material

Teliospore initials of Puccinia podophylli develop from binucleate sporogenous cells lining the base of the telium. The teliospores are formed in basically the same fashion as those of other rusts that have been examined at the ultrastructural level. The long, straight or slightly curved spines present on mature teliospores initially develop as slight bulges or protrusions on the spore surface. The spore wall in such a region then evaginates to form a slender spine that is initially filled with cytoplasm. The cytoplasmic material is then progressively excluded from the tip of the spine as a result of the thickening of the spine wall. Mature teliospores of P. podophylli possess a wall consisting of a thick, outer, electron-dense layer in which stratification is only rarely visible and an inner thinner, less electron-dense layer.

Surface morphology of aeciospores, urediniospores, and teliospores of Uromyces trifolii-repentis

1988 ◽  
Vol 66 (6) ◽  
pp. 1129-1134 ◽  
Author(s):  
S. F. Hwang ◽  
M. E. Neuwirth ◽  
K. F. Chang
Keyword(s):  
Surface Morphology ◽  
White Clover ◽  
Trifolium Repens ◽  
Cell Layer ◽  
Spore Wall ◽  
Germ Pore ◽  
Transmission Electron ◽  
Hilar Region ◽  
Trifolium Repens L ◽  
Electron Microscopes

The surface markings of the spores from the aecial, uredinial, and telial stages of Uromyces trifolii-repentis Liro on leaves and petioles of small white clover (Trifolium repens L.) were examined using scanning and transmission electron microscopes. The short, cylindrical aecium was borne within a peridium which was one cell layer thick. The peridial cells were rhomboidal with irregular club-shaped ornaments. The yellowish aeciospores were densely ornamented with smooth, knoblike verrucae. Thin areas of the spore wall were differentiated into germ pores. Two or three germ pores were equatorially arranged on the golden-brown urediniospores, which except for a circular hilar region were evenly covered with minute conical spines. The spines were situated singly in very shallow depressions surrounded by circular ridges. The dark-brown teliospores had smooth walls with a few linearly arranged fine warts, and the walls were thicker at the apex than on the side. A pale papilla covered the germ pore at the apex of the teliospore, which was borne singly on the fragile pedicel.

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