This document discusses the phylum Chytridiomycota and order Chytridiales. It provides details about: 1) The life cycle of Synchytrium endobioticum, which causes potato wart disease, including asexual reproduction through zoospores and sexual reproduction through zygospores. 2) General characteristics of Chytridiomycota including having uniflagellate zoospores, living mainly in water, and reproducing sexually through isogamy, anisogamy, or oogamy. 3) Differences between the fungi Rhizopus and Mucor, which are both in the order Mucorales of the phylum

1. Chytridiomycota
Chytridion means – Little pot
N.H. SHANKAR REDDY
2nd Ph.D. Plant Pathology
Annamalai University

3. General characters
• The chief characteristic feature of this class is the production
of uniflagellate reproductive cells (zoospores and
planogametes).
• The single flagellum is of a whiplash type and is inserted
posteriorly. The zoospore with a posteriorly inserted flagellum
is called opisthocont.
• The flagellum is attached to the blepharoplast within the cell.
• Majority of the members occur in water.

4. • The hyphe are coenocytic. Chitin is the chief constituent of
the cell of hyphal wall.
• The asexual reproductive organs are the sporangia, each of
which produces numerous tiny, uninucelate and uniflagellate
opisthocont zoospores.
• The liberated zoospores swim for a time. Later each retracts
its flagellum and undergoes encystment. After a short period
of rest, the encysted spore germinates. The sexual
reproduction may be isogamous or anisogamous. In some it is
typically oogamous (Monoblepharidales).

5. Order – Chytridiales
(Synchytridium endobioticum)
Life cycle of Synchytridium endobioticum (Potato wart disease)
Symptoms – Cells enlarged due to hypertrophy and form warty
outgrowth.
Phylum – Chytridiomycota
Class – Chytridiomycetes
Order – Chytridiales
Family – Synchtriaceae
Genus – Synchytrium
Species - endobioticum

6. Potato wart symptoms

8. Asexual reproduction
• Large number of uniflagellate
zoospores are released from the
infection portion.
• After 2hrs of swimming they reach
potato tubers
• The flagellum shreds and enters
into host and for amoeboid shape.
• The amoeboid zoospore increase
size and form prosorus
(zoosporangium)
• After repeated mitotic divisions and
form 32 nuclei
• The prosorus divided into 4-9
divisions and produce 200-300
nuclei
• Each nuclei develop into develop
into a uniflagellate zoospore which
swims and attaches to the host
Sexual reproduction
• The water released zoospores
functions s gamates.
• Karyogamy and plasmgamy takes
place and a biflagellate zygote
formed
• Hypertrophy and hyperplasia takes
place
• The diploid zygote enlarges an
develop into resting sporangium
• This resting sporangium undergoes
reduction division and form
uninucleate daughter protoplats each
of which converted into a haploid
zoospores.
• The haploid zoospores are liberated
by the rupturing of the infected host
and the host life cycle is repeated

10. Zygomycota
General characters
• Otherwise called as Yolk fungi
• Cell wall is composed of Chitosan chitin
• Produce rhizoids (anchoring organ) and stolon (attachment organ)
• The sporangia is supported by sporangiophore where the sporangiospores are
packed inside the sporangium
• Zygomycota fungi can reproduce by means of both sexual and asexual
reproduction
• Asexual reproduction by means of aplanospores (non- motile) or sporangia or
conidia and sexual reproduction by means of gametangial copulation
• Asexual spores – sporangiospore, chlamdospore, oidia
• Sexual spores – zygospores (example of diploid sexual spore, it is a thick walled
resting spore)
• Classified as 3 orders Mucorales (pin moulds), Entomophthorales and
Zoopagales
• Eg – Rhizopus, Mucor and Pilobolus

12. • Order – Mucorales (Pin moulds)
• Order – Endogonales (Pea truffles)

13. Difference Rhizopus and Mucor
Particulars Rhizopus Mucor
Other names Commonly called as bread
mould
Commonly called as pin
mould
Mycelium
Mycelium is differentiated
into three kinds of hyphae
viz., stolons and rhizoids
and sporangiophores
Mycelium consists of only
one kind of hyphae and is
not differentiated into
Stolons and rhizoids.
Hyphae and
holdfast
Absorptive hyphae or
holdfasts are present
Holdfast are absent and
are not specialized well
Sporangiophores
Sporangiophores are
developed into clusters
(groups) above the nodes
and arise only from the
junction of rhizoids and
stolons.
Sporangiophores may
develops from any point
Spore
dissemination
Spores are easily blown
away by wind, thus a
common contaminat of air
Spores are not easily
disseminated and remains
attached to the columella.
Collumella Columella in most species
become more or less dome
or umbrella shaped after
dehiscence of sporangium
Columella doesnot change
shape after dehiscence of
sporangium
Examples Rhizopus stolonifer Mucor mucedo

14. Zygospore
(sexual
spore of
Zygoycota)