Ultrastructural observations on Helvellaceae (Pezizales). Ascosporogenesis of selected species of Helvetia

The ultrastructure of ascosporogenesis including observations on spore delimitation, primary wall deposition, and formation of the secondary wall is examined in three species of the genus Helvella. The double membranes delimiting the spores and the ascus plasmalemma stain identically with silver proteinate poststain. Primary wall formation is similar in all species examined, although very early development was observed only for H. macropus. Secondary wall formation, which results in the characteristic spore ornamentation, appears to be quite similar for the three species. In addition, observations are made on the structure and origin of the epispore and on cytological details of the epiplasm and sporoplasm relating to spore ontogeny.

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Ultrastructural observations on Helvellaceae (Pezizales, Ascomycetes). IV. Ascospore ontogeny in selected species of Gyromitra subgenus Discina

Canadian Journal of Botany ◽

10.1139/b90-043 ◽

1990 ◽

Vol 68 (2) ◽

pp. 317-328 ◽

Cited By ~ 10

Author(s):

James W. Kimbrough ◽

Chi-Guang Wu ◽

Jack L. Gibson

Keyword(s):

Key Words ◽

Secondary Wall ◽

Spore Wall ◽

Wall Material ◽

Wall Structure ◽

Primary Wall ◽

Spore Ornamentation ◽

Wall Formation ◽

Secondary Wall Formation ◽

Definition Of

The ultrastructure of ascospore ontogeny and spore wall microchemistry are described in three sessile, discoid species of Gyromitra previously placed in Discina. Silver proteinate and barium permanganate were used as poststains to enhance the definition of various wall layers and spore organelles. Early stages of ascosporogenesis and primary wall formation are similar to those described in other species of Pezizales. Secondary wall formation, which results in characteristic spore ornamentation, is similar in Gyromitra brunnea, Gyromitra leucoxantha, and Gyromitra perlata. Mature spores of these species differ in the size and shape of translucent lacunae within the secondary wall, and in the morphology of apiculi. The lacunae originate through blebbing of primary wall material through the epispore into the secondary wall, resulting in the isolation of electron-translucent primary wall clumps within the electron-dense secondary wall. These and other ultrastructural observations of apothecial tissues support the maintenance of the Helvellaceae (sensu lato) to include taxa of the tribes Helvelleae, Discineae, and Rhizineae. Phylogenetic linkages of these taxa to other families of Pezizales are suggested. Key words: ascosporogenesis, ascospore wall structure and microchemistry, discomycete systematics and phylogeny.

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The Nature of Reaction Wood III. Cell Division and Cell Wall Formation in Conifer Stems

Australian Journal of Biological Sciences ◽

10.1071/bi9520385 ◽

1952 ◽

Vol 5 (4) ◽

pp. 385 ◽

Cited By ~ 12

Author(s):

ABW Ardrop ◽

HE Dadswell

Keyword(s):

Cell Wall ◽

Cell Division ◽

Secondary Wall ◽

Compression Wood ◽

Normal Wood ◽

Reaction Wood ◽

Primary Wall ◽

Wall Formation ◽

Tracheid Length ◽

Secondary Wall Formation

Cell division, the nature of extra-cambial readjustment, and the development of the secondary wall in the tracheids of conifer stems have been investigated in both compression wood and normal wood. It has been shown that the reduction in tracheid length, accompanying the development of compression wood and, in normal wood, increased radial growth after suppression, result from an increase in the number of anticlinal divisions in the cambium. From observations of bifurcated and otherwise distorted cell tips in mature tracheids, of small but distinct terminal canals connecting the lumen to the primary wall in the tips of mature tracheids, and of the presence of only primary wall at the tips of partly differentiated tracheids, and from the failure to observe remnants of the parent primary walls at the ends of differentiating tracheids, it has been concluded that extra-cambial readjustment of developing cells proceeds by tip or intrusive growth. It has been further concluded that the development of the secondary wall is progressive towards the cell tips, on the bases of direct observation of secondary wall formation in developing tracheids and of the increase found in the number of turns of the micellar helix per cell with increasing cell length. The significance of this in relation to the submicroscopic organization of the cell wall has been discussed. Results of X-ray examinations and of measurements of� tracheid length in successive narrow tangential zones from the cambium into the xylem have indicated that secondary wall formation begins before the dimensional changes of differentiation are complete.

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Ultrastructural observations on Helvellaceae (Pezizales). II. Ascosporogenesis of Gyromitra esculenta

Canadian Journal of Botany ◽

10.1139/b88-239 ◽

1988 ◽

Vol 66 (9) ◽

pp. 1743-1749 ◽

Cited By ~ 13

Author(s):

Jack L. Gibson ◽

James W. Kimbrough

Keyword(s):

Secondary Wall ◽

Primary Wall ◽

Wall Formation ◽

Fibrillar Material ◽

Wall Deposition

The ultrastructure of ascosporogenesis in Gyromitra esculenta (Pers.) Fr. is examined and compared with that reported for other Pezizales. Observations are made on spore delimitation, primary wall deposition, and formation of the secondary wall. Primary wall formation is similar to that reported for other species of Pezizales. The more or less smooth, electron-dense secondary wall appears to be derived from loose, fibrillar material of the perisporal sac. Observations are also made on structure and origin of the epispore and on cytological details of the epiplasm and sporoplasm relating to spore ontogeny.

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