Allomyces classification,Introduction,Life Cycle.pdf

This presentation provides an overview of Allomyces, an aquatic fungus from the Zoopagomycota class. It includes key details on its taxonomy, morphology, and lifecycle. The content focuses on its biological features and growth in aquatic environments. Ideal for students and researchers, this slide deck offers a concise exploration of Allomyces without delving into its ecological or biotechnological significance.

1. Allomyces
Phylum: Chytridiomycota
Presented by:
Faria Jahan
ID:20BOT-029
Department of Botany,
BSMRSTU,Gopalganj-8100

2. Phylum:
Chytridiomycota
Division:
Blastocladiomycota
Class:Blastidiomycetes Order:Blastocladies
Genus: Allomyces
Classification

3. INTRODUCTION
➢Allomyces belongs to phylum chytridiomycota .
➢Allomyceswas first discovered in India in 1911
by E.J. Butler.
▪Habitat: found in soil & fresh water.
▪Distribution: widely distributed over
the globe.
➢It is also called"aquatic"fungi.
➢Species in the genus have a polycentric(a
thallus with many centers at which
reproductive organs (sporangia or resting
spores) are formed) thallus.
➢Three types of life cycles have been discovered
in Allomyces, & on that basis Emerson(1941).
[REf-Introductory Mycology
Alexopolous, Mims, Blackwell]

4. MORPHOLOGY
Allomycesexihibit filamentous development.
Thethallusconsists ofa groupof welldeveloped, branchedrhizoids by
meansof which thefungusattaches itselfto thesubstrate.
A trunklikebase& numerousside branchesusuallydichotomously
branched on whichreproductiveorgans are formed.
Septaareabsent exceptat thebasesofthe reproductiveorgans& in
olderhyphae.
Asexualreproductionbyzoospores thathave
awhiplash(smooth),posterior type flagella.
Zoospores produced in zoosporangia.
Sexualreproductionmay beisogamy,anisogamy or oogamas.
[Ref-Introductory Mycology by
Alexopoulos ,Mims, Blackwell]

5. Figure:4-15 Thick walled resistant sporangia ofAllomyces
as seen light microscopy[Photograph by C.W. Mims]
[Ref- Wikipedia]
[Ref-Introductory Mycology
By Alexopoulos]

6. Thallus structure of Allomyces
➢The thallus in all the species is hyphal & is called the mycelium.
➢Itis filamentous& attachedto thesubstatum by atuftof deligatebut wellformed, branchedrhizoidal
hyphaeconstituting therhizoiudal system.
➢From the latter arisesa singlestoutbutslenderhyohaeformedthe lower trunklike portion.
➢InAllomyces they are not formedin conjunction with celldivision.
➢The hyphae arethusmultinucleate & coenocytic .[Ref-Introductory Mycology by Alexopoulos , Mims ,
Blackwell]
➢Theseptain Allomyces are oftenreferredto asfalse septabecausethey do notcompletetly separatethe
protoplasmof adjacentsomaticsegments.
➢Thewell-developedhyphaearedichotomouslybranched.

7. Sexual Reproduction of Allomycesmacrogynus
❖Allomycesmacrogynus is an example of an anisogamous species.
STAGE-1
➢Gametothalli & Sporothalli of the same strain have the same general nutritional requirements [Machlis &
Crasemann,1956].(Fig.4-17,A)
➢When they reach a certain stage of matuarity,the gametothalli produce colorless female gametengia &
orange male gametengia in close proximity to one another(Fig. 4-17,B) & usually in a 1:1 ratio.
➢The male gametengia are smaller than the female gemetengia.
STAGE-2
➢The orange color in the cytoplasm ,which eventually becomes differentiated into male gamets.
➢Both types of gametengia release motile gamets(planogamets ,plano=latin word) in the water(fig.4-17,D)

8. ➢Both male & female gamets posses a prominent nuclear cap.
STAGE -3
➢The female gametengia& gamets of Allomyces produce a pheromone called sirenin(Greek word) to
which male gamets are attracted (Machilis , 1958a, b).
➢Male gametesalsoproducea femaleattractingpheromoneby thenameof parisin.
➢Shortly after their release from the gametangia , the gamets of Allomyces fuse in
pairs(copulation)(Fig.4-17,E).
➢Nuclear caps of the two orginal gametsmay or may not fuse.
STAGE-4
➢In this fuse gamet ,first phase is plasmogamy(the fission of the protoplast ),(Fig.4-17,F) & the second phase
is karyogamy(the fission of the two nucli(plural)),(Fig.4-17,G)
➢Karyogamyis the finalstepof "HAPLOPHASE"

9. STAGE-5
➢In Allomyces the mature Zygote is initially biflagellate.
➢The Zygoteeventuallyloses its flagella, encysts ,& soongerminates.
➢Firsta germ tubeisproducedthatdevelopsinto rhizoids(Fig.4-17,H).
➢It is thefirststep of" DIPLOPHASE"
STAGE-6
➢Then the main body of the zygote enlarges & give rise to the first hyphal tube , which elongates ,branches
dichotomously ,& develops into a diploid sporothallus(Fig.4-17,I).
➢At maturity, thesporothalli fromtwo types ofsporangia,thin walled ,elongate,colorless
zoosporangia(mitosporangia)& oval,thickwalled,resistent sporangia(meiosporangia) (Fig.4-
17,I)thatcontainmelaninpigments & appear reddishbrown.

10. STAGE-7
➢The thin walled zoosporangia germinate soon after their formation, releasing diploid
zoospores(mitospores0s) that swim about for a time (Fig.4-17,J)
➢Encyst,& give rise to sporothalli,thus repeating the diploid generation.
STAGE-8
➢Meiosis in resistant sporangia takes place at the time of germination(wilson,1952) & result in the
formation of haploid zoospores(meiospores) (Fig. 4-17,K) that are slighty smaller than the diploid
zoospores).
REF-Introductory of Mycology
C.J .ALEXOPOUlOS
C.W.MIMS
M.BLACKWELL

13. Thank you
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