Ultrastructure of Cephaleuros Virescens (Chroolepidaceae; Chlorophyta). Ii. Gametes

Chapman, Russell L.

doi:10.1002/j.1537-2197.1980.tb07619.x

Cited by 23 publications

(1 citation statement)

References 17 publications

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“…Structures observed paralleled those detailed in studies of Trentepohliales and Cephaleuros spp. [12,13,18,19]; however, in those studies, individual zoospores, isogametes, and/or meiozoospores were observed.…”

Section: Discussionmentioning

confidence: 79%

Distinctive Features of the Orange Cane Blotch Disease Cycle on Commercial Blackberry (Rubus fructicosis)

et al. 2023

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The high humidity and short, mild winters of the southeastern United States are conducive to many plant diseases including orange cane blotch (OCB), caused by the algal species Cephaleuros virescens (Cv). Since its discovery on blackberry, its presence has been associated with cane cracking, cane girdling, and yield loss. Research detailing the disease cycle on blackberry is limited and is largely inferred from the interactions of Cv with its other hosts. To further detail the disease cycle of OCB, diseased blackberry canes were examined by photography and microscopy. By combining observations made from photography and microscopy, key events in the disease cycle of OCB on blackberry were elucidated as they correspond to blackberry phenology. The alga was observed to be active for a majority of the season, only exhibiting apparent dormancy from December through mid-April, concurrently with blackberry. While it appeared that the presence of algal sexual reproductive structures did not coincide with emerged primocanes, asexual reproductive structures were observed during the period when primocanes emerged. All new infections on newly emerged primocanes appeared around mid-summer, indicating a single infection cycle per year for OCB. These findings provide a foundation for further study and the development of targeted management strategies for OCB.

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Section: Discussionmentioning

confidence: 79%

Distinctive Features of the Orange Cane Blotch Disease Cycle on Commercial Blackberry (Rubus fructicosis)

et al. 2023

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Ultrastructure of Cephaleuros Virescens (Chroolepidaceae; Chlorophyta). Iii. Zoospores

Chapman

1981

American J of Botany

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Transmission electron microscopic examination of Cephaleuros virescens Kunze growing on leaves of Camellia spp. and Magnolia grandiflora L. indicates that unreleased zoospores in mature zoosporangia are similar to those produced by the related genus Phycopeltis epiphyton Millardet and unlike the quadriflagellate motile cells produced by taxa in other families of Chlorophyta. The zoospores bear four smooth isokont bilaterally “keeled” flagella containing typical “9 + 2” axonemes and lacking scales. Flagellar insertion is apical and the parallel basal bodies overlap laterally at two levels. A cross section through the four basal bodies shows a trapezoidal arrangement wherein the two upper (anterior) basal bodies are closer together than are the lower (posterior) two. Serial sections indicate that diagonally opposing upper and lower basal bodies anchor flagella which emerge from the same side of the apical papilla. Each of the four basal bodies is associated with a microtubular spline which extends beneath the plasmalemma to the posterior end of the zoospore. A distinct multilayered structure is associated with each of the lower basal bodies. A nucleus, mitochondria (two of which are closely associated with the nucleus and spline microtubules), a chloroplast, and cytoplasmic haematochrome droplets are present in each zoospore. Pyrenoids and eyespots are absent. Flagellar insertion is characterized by “reversed bilateral symmetry”; and zoospores with both right‐handed and left‐handed arrangements are produced. The ultrastructure of the zoospores clearly indicates that: 1) the mode of flagellar insertion: 2) morphology, number, and arrangement of multilayered structures, and 3) bilaterally keeled flagella are characteristic of the Chroolepidaceae.

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Ultrastructure of Cephaleuros Virescens (Chroolepidaceae; Chlorophyta). Iv. Absolute Configuration Analysis of the Cruciate Flagellar Apparatus and Multilayered Structures in the Pre‐ and Post‐release Gametes

Chapman

Henk

1983

American J of Botany

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Transmission electron microscopy of pre‐release and post‐release biflagellate gametes of Cephaleuros virescens has produced comparative data on these cells and on the detailed absolute arrangement of the flagellar apparatus. In all major respects including the presence of two multilayered structures (MLS's) the closely compacted, non‐motile but mature pre‐release gametes are similar to the mature, free swimming post‐release gametes. The elongated shape of the free‐swimming gametes differs from the more compact form of the pre‐release gametes, but does not reflect a major difference in the arrangement of internal components. The flagella are bilaterally keeled and each keel contains a cylindrical element. Each flagellar base is encircled by a densely staining collar of modified plasmalemma at the point of entry into the apical papilla. The equal anterior flagella enter the papilla from opposite sides; their basal bodies are parallel and overlapping. Each terminates in a densely staining terminal cap. No capping plate is present. Each basal body is associated both with a three‐layered MLS, the anterior layer of which becomes a lateral microtubular spline of 2 to 8 microtubules, and with an additional medial compound root of two layers of microtubules (2 over 4 or 5). Both the compound microtubule root and the spline may acquire additional microtubules as they extend distally in close proximity to mitochondria and the plasmalemma. No striated roots, or rhizoplasts, have been observed. Two densely staining plaques are associated with the plasma membrane at specific anterior sites and may be comparable to the presumptive mating structures seen in other green algal motile cells. The reversed bilateral symmetry of the cells produces two possible arrangements of the flagellar apparatus, namely, a 11/5 (or left‐handed) arrangement or a 1/7 (or right‐handed) arrangement. Only 11/5 cells have been found. Despite the presence of distinct multilayered structures, some aspects of the gametes of Cephaleuros quite closely resemble the cruciate motile cells of algae now regarded by some authors as typical of Ulvophyceae, sensu Stewart and Mattox.

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Ultrastructure of Cephaleuros Virescens (Chroolepidaceae; Chlorophyta). Ii. Gametes

Cited by 23 publications

References 17 publications

Distinctive Features of the Orange Cane Blotch Disease Cycle on Commercial Blackberry (Rubus fructicosis)

Distinctive Features of the Orange Cane Blotch Disease Cycle on Commercial Blackberry (Rubus fructicosis)

Ultrastructure of Cephaleuros Virescens (Chroolepidaceae; Chlorophyta). Iii. Zoospores

Ultrastructure of Cephaleuros Virescens (Chroolepidaceae; Chlorophyta). Iv. Absolute Configuration Analysis of the Cruciate Flagellar Apparatus and Multilayered Structures in the Pre‐ and Post‐release Gametes

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