Sexual reproduction in the<i>Peronosporomycetes</i>(chromistan fungi)

Dick, M.W.

doi:10.1139/b95-314

Cited by 69 publications

(66 citation statements)

References 47 publications

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“…Recently it has been pointed out that systematics of downy mildews needs to be defined on the basis of more accurate and precise criteria (Hall, 1996) but unfortunately numerous important species are still inadequately described (Dick, 1995). The ultrastructural approach has been recommended and seems to be particularly interesting both for phylogenetic and systematic purposes.…”

Section: Discussionmentioning

confidence: 99%

A cytological and ultrastructural study on the maturation and germination of oospores of Plasmopara viticola from overwintering vine leaves

Vercesi¹,

Tornaghi²,

Sant³

et al. 1999

Mycological Research

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Observations on cytological and ultrastructural changes in Plasmopara viticola oospores were carried out during the overwintering period. Three types of oospores were observed. Type I, characterized by a thin inner oospore wall (IOW), large lipid globules and two nuclei, was recovered only in samples collected in October. These oospores were considered to be immature. Maturation occurred during November and involved a noticeable increase in thickness of the IOW, fusion of nuclei, formation of an ooplast and break up of large lipid globules into smaller ones (type II oospores). A few oospores (type III) showed abnormal organization with very large lipid globules and less frequently discernible nuclei. IOW solubilization, dissolution of the ooplast and lipid globules and nuclear division were the first detectable events during oospore germination. Germinating oospores produce a germ tube which was terminated by a sporangium. In its young stage, the sporangium had a thick wall and an unusual multi-layered membrane. During this phase, nuclear divisions took place in the sporangium. While sporangium development progressed, the ribosome density in the cytoplasm decreased and mitochondria, initially roundish with evident cristae, became their usual tubular profile. The plasma membrane had a typical structure and storage organelles, such as finger print vacuoles and lipid globules, became more numerous in the cytoplasm. Larger vacuoles contained the flagella of differentiating zoospores.

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Section: Discussionmentioning

confidence: 99%

A cytological and ultrastructural study on the maturation and germination of oospores of Plasmopara viticola from overwintering vine leaves

Vercesi¹,

Tornaghi²,

Sant³

et al. 1999

Mycological Research

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“…The oomycotes are mycelial protoctists that have swimming propagules (zoospores) resembling planktonic heterotrophic flagellates (Dick 1990, 'E-mail: newell@uga.cc.uga.edu 0 Inter-Research 1997 Nakagiri 1993, Fell & Newel1 1997, Kohlmeyer et al 1997. The oomycotes were formerly termed 'zoosporic fungi', and are still alternatively referred to as 'chromistan fungi' or Peronosporomycetes (Dick 1995), although they are not evolutionarily close to the Kingdom Fungi (references in Erwin & Ribeiro 1996, Fuller 1996, Newel1 1996. We use the word 'fungi' herein only to refer to members of the Kingdom Fungi.…”

Section: Introductionmentioning

confidence: 99%

Competition among mangrove oomycotes, and between oomycotes and other microbes

Sy¹,

Jw²

1997

Aquat. Microb. Ecol.

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ABSTRACT-Competition experiments were performed using precolonized leaves or leaf disks of red mangrove Rhizophora mangle with: (1) disks containing pure cultures of single species of marine true fungi or species of Halophytophthora (the principal genus of marine oomycotes); and (2) leaves bearing bacterial films. Preoccupied leaves were exposed to natural microflorae in mangrove creeks at 2 Cays in the Bahaina Islands, or placed in laboratory seawater enclosures wherein pairs of halophytophthoras were given equivalent opportunity to occupy fresh leaf material. The ubiquitous coastal-marme oomycote H. vesicula was found to be an able competitor versus true fungi and versus other halophytophthoras. Against other halophytophthoras, this was true for both primary and secondary resource capture. The one exception among the fungi was a species (Dendryphiella salina) common in decaying drift material in high-intertidal zones. H. spinosa was a weak competitor with true fungi and with H. vesicula, though it was not displaced by H. vesicula, and H. spinosa could depress the frequency of H. vesicula occupation when H. spinosa was well established. H. bahamensis did not routinely form sporangia, preventing identification and firm conclusions regarding compet~tiveness, other than that it could not block H. vesicula, but could block H. spinosa from entering its occupied arenas. When bacterial films were present on leaves prior to access by halophytophthoras, the occupation frequency of halophytophthoras was sharply depressed (by about 70 to 90% with 48 h bacterial films), including for H. vesicula, implying that in some types or parts of mangrove systems, submerged-leaf decomposition may sustain low levels of participation by halophytophthoras.

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“…2C). This association is strikingly similar morphologically to a peronosporomycete oogonium to which are attached several paragynous antheridia (for details, see Dick 1969Dick , 1995Dick , 2001. It is interesting that among the type-2 and type-3 spheres are also specimens that show a similar association between the large spheres and smaller ones (e.g., Figs 3E-I, 4C-E).…”

Section: Discussionmentioning

confidence: 77%

“…If this hypothesis is accurate, then these fossil zygomycetes have produced one prominent and one undifferentiated, inconspicuous suspensor (see Benny et al 2001). Unfortunately, wall features are of little help in distinguishing specimens as either related to the Peronosporomycetes or Zygomycota since thick-walled and/or prominently ornamented oogonia/sporangia occur in both groups (e.g., Zycha et al 1969;Benjamin 1979;Dick 1995Dick , 2001. Moreover, it has been shown in several Carboniferous peronosporomycetes that oogonial wall features can differ from those seen in any extant member of this group (Dotzler et al 2008, Krings et al 2010a.…”

Section: Discussionmentioning

confidence: 99%

A fungal community in plant tissue from the Lower Coal Measures (Langsettian, Lower Pennsylvanian) of Great Britain

Krings¹,

Dotzler²,

Taylor³

et al. 2010

Bull. Geosci.

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A diverse assemblage of microfungal remains occurs in periderm cells of a lycophyte from the Lower Coal Measures (Carboniferous) of Great Britain. Among the remains are several types of hyphae, including septate forms with catenulate swellings and small, narrow forms that are multi-branched. There are also several types of spherical structures that differ from one another in size, wall thickness, and ornamentation. The most common of these is interpreted as peronosporomycete oogonia based on specimens with attached antheridia. Other forms may also represent Peronosporomycetes, but might as well belong to the Zygomycota. Oval or tear drop-like structures that occur in clusters or chains are interpreted as conidia. Host reactions in the periderm cells are rare, with the exception of small callosities. Although it is not possible to conclusively identify the (precise) systematic affinities of the fungi, this discovery is significant because it demonstrates that one of the most common plant tissues in the Carboniferous (i.e. lycophyte periderm) provided a suitable habitat for several endophytic organisms at the same time. The overall excellent preservation of the host tissue, together with the evidence of host reactions, indicates that at least some of the endophytes were biotrophic.•

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Sexual reproduction in thePeronosporomycetes(chromistan fungi)

Cited by 69 publications

References 47 publications

A cytological and ultrastructural study on the maturation and germination of oospores of Plasmopara viticola from overwintering vine leaves

A cytological and ultrastructural study on the maturation and germination of oospores of Plasmopara viticola from overwintering vine leaves

Competition among mangrove oomycotes, and between oomycotes and other microbes

A fungal community in plant tissue from the Lower Coal Measures (Langsettian, Lower Pennsylvanian) of Great Britain

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