Sexual reproduction in Penicillium
Dangeard in 1907 observed the sexual reproduction in P.
vermiculatum , which is as
follows:
· A long, straight and club-shaped ascogonium(female)
developed from mycelium.
· It’s nucleus divides mitotically into
64 nuclei.
· Simultaneously, a uninucleate male antheridial
branch arises and coils around the female body.
· Then a septa forms to make terminal antheridia
which swells , turns club- shaped and uninucleate.
· The antheridial tip touches the wall
of the ascogonium & the point of contact dissolve but antheridial nucleus
does not pass into the ascogonium i.e. remains non- functional .
· Meanwhile , ascogonial nuclei get paired
(termed autogamy) & after that segmented
leaving dikaryon in each chamber .
(In P. glaucm instead of autogamy it performs plasmogamy i.e.
the content of antheridium i.e. 32 -64 nuclei formed by repeted mitosis in trichogyne migrate in the female ascogonium ).
· From each bi-nucleate chamber new
ascogenous initial developed which are binucleate
and turned into ascogenous hyphae which are branched .
Development of Ascus:
In P. vermiculatum all
binucleate cells of ascogenous hyphae developed into globose ascus mother
cell in which n+n turned into 2n & the structure termed as young
ascus. It is called direct method .
(In other species tip of ascogenous hyphae turns hook -like
& segmented into 3 cells :-
(i) Tip
ultimate with a nucleus
(ii) Penultimate cell
with 2 nuclei
(iii) Uninucleate basal cell .
The 2 nuclei of penultimate
cell turned 2n .It is called indirect method).
· Then in both cases meiosis is
performed & then mitosis take place .Hence the 2n of the young ascogonium turned
into 8 haploid nuclei in a mature ascus .
Formation of cleistothecium:
Meanwhile, numerous sterile hyphae inter-woven to form the fruit body
enclosing many ascus .
Liberation of spores :
When spores mature , the asci dissolves and ascospores released within
the fruit body.Then the peridium decayed
to liberate the spores in air.
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