Division Oomycota

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Division Oomycota
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Oomycotans are not fungi, but belong to kingdom
Chromista
Characters Neclei Histone Microtubules Mitochondri
a Storage compound Cell wall Steroles
Oomycota Diploid Trypical centrioles Like
plant Sensitive to colchicine Tubular Mycolaminari
n Cellulose, Glucan Plant sterole
True fungi Haploid Spindle pole body Like
animal Sensitive to Benzimidazoles Cisternae Glyco
gen Chitin Ergosterol
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Main characteristics
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Zoosporangium
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Zoospore
L www.apsnet.org/.../PhotosW-Z/ zoospore.htm R
www.mycolog.com/chapter2b.htm
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Life cycle of Oomycota
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plantpath.unl.edu/peartree/homer/
sec.skp/protista.html
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Activity of sex hormone A-D of Achlya
Hormone A B C D
Source Somatic female thalli Male thalli
bearing antheridial initials Oogonial
initials Anteridia
Biological function Induce formation of
anteridial branchs on male thalli Induce
formation of Oogonial initials Attracts
anteridial branchs to oogonial initials and act
in cojugation with thigmothophic response to
induce antheridium delimitation Course oogonium
delimitation and oosphere differentiation
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Classification Division Oomycota Subclass
Saprolegniomycetidae Order Saprolegiales Subc
lass Peronosporomycetidae Order
Leptomitales Order Rhipidiales Order
Lagenidiales Order Peronosporales
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Order Saprolegniales Characteristic
u Live in water mostly u Saprophyte or
parasite u Zoosporangia are produced at the
hyphae tip u Usually several oospores in an
oogonium u Genus Saprolegnia, Aphanomyces,
Achlya, ect.
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Zoosporangia of some genus in Saprolegniales
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Zoosporangia of Saprolegnia sp.
www.ntlabs.co.uk/ microscope_diagnosis.htm
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Saproleniois
homepages.tesco.net/davyreynolds/
fishhealth/fungus.htm
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Epizootic Ulcerative Syndrome (EUS) caused by
Aphanomyces invadans
www.vims.edu/pfiesteria/ Aphano.html
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Root rot of pea caused by Aphanomyces euteiches
www.ag.uiuc.edu/cespubs/pest/ articles/200204h.htm
l
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Achlya on frog
www.bsu.edu/classes/ruch/ msa/porteretal/3-37.jpg
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Order Peronosporales Characteristics u
Large order u Live in water, amphibian and
soil u Zoosporangia are produce on either
sporangiophore or somatic hyphae u
Zoosporangia are oval or lemon shape u
Genus Pythium, Phytophthora, Albugo, Peronospor
a Plasmospora
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Pythium spp.
u Sporangia are direct from somatic hyphae u
Saprophyte, Parasite or Mycorhiza u Plant
disease e.g. dampling off, root rot, foot rot
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Lice cycle of Pythium debaryanum
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Damping off cause by Pythium spp.
www.fsagx.ac.be/pp/Phytopat/ Partie0/fonte_Pythium
.jpg
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Phytophthora spp.
u Lamon-shaped sporangia on branched
sporangiophore u P. infestans Late blight of
potato u P. palmivora ???????????????????,
???????, ?????? ????????? u P. parasitica
??????????????????? u P. erythroseptica Pink rot
of potato
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Lice cycle of Phytophthora infestans
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Zoosporangium of Phytophthora sp.
pro.wanadoo.fr/lnpv/phyt.html
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Late blight of potato caused by Phytophthora
infestans
www.redepapa.org/potato.html
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Late blight of potato caused by Phytophthora
infestans
www.mycolog.com/chapter2b.htm
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Irish famine in 1847 due to Phytophthora infestans
www.mycolog.com/chapter2b.htm
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Albugo spp.
u Several sporangia are produced on a short,
club-shaped sporangiophore u A. candida
are known as white rust causing disease on
vascular plants such as cabbage u A.
ipomoeae-panduranae causing disease on sweet
potato and morning glory
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Life cycle of Albugo candida
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White rust disease caused by Albugo sp.
www.apsnet.org/education/LabExercises/
Oomycetes/Top.html
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White rust caused by Albugo candida
www.mycolog.com/chapter2b.htm
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Albugo portulacae
biodidac.bio.uottawa.ca/thumbnails/
filedet.htm?File_nam...
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Peronospora spp.
u Obligate parasite of vascular plant with
narrow host rang u Causing downy mildew u
Sporangia are borne on unmistakable-branched
sporangiophore u Sporangiophores are produce
through out plants stroma u Some species,
sporangia do not produce zoospore, but
germinate in stead
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Life cycle of Peronospora viticola
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Sporangiophore characteristic of Peronosporaceae
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Peronospora destructor ???-???????? P.
parasitica ????????????? P. tabacina
????? Sclerospora graminicola ???? Plasmopara
viticola ????? Pl. australis ?????? Bremia
lactucae ????????? Bremia spp. Compositae
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www.oznet.ksu.edu/.../problems/
Grapes,DownyMildew.htm
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Sporangia of Peronospora sp.
www.mycolog.com/chapter2b.htm
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Disease cycle of Eutypa diaback.
ohioline.osu.edu/b861/ b861_59.html
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Downy mildew on grape caused by Plasmovara
viticola
www.mycolog.com/chapter2b.htm
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Blue mould of tobacco caused by Peronospora
tabacina
www.mycolog.com/chapter2b.htm