Polyporus is a genus of wood-rotting fungi that causes decay in trees. It has a vegetative mycelial stage that exists in two phases - a primary monokaryotic mycelium and a secondary dikaryotic mycelium. The secondary mycelium develops underground and secretes enzymes to digest wood. Fruiting bodies called basidiocarps form above ground on wood surfaces. Basidiocarps are shelf-like or bracket-shaped structures with pores on their undersides containing basidia that undergo karyogamy and meiosis to produce haploid basidiospores for reproduction.
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Polyporus is known as wood rotters
cause wood rot of s timber trees
conifers, oak, apple, maple walnut, pear,
Acacia etc. P. sulphureus, (sulphur mushroom,)
causes wood rot of oak and other trees and
has large sulphur yellow fruiting bodies
P. betulinus causes the heart rot of birch and
some other coniferous trees. P. squamosus
causes heart rot of Ulmus.
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The fruiting bodies - BASIDIOCARP
annual
In the form of brackets and shelves
stalked
fleshy when young
hard and leathery or corky at
maturity.
Young fruiting bodies of P.
sulphureus are edible
mature fruiting bodies of P. lucida
are used as decorative pieces in the
houses
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Vegetative Mycelium :
Exists in two phases
a) Primary Mycelium
b) Secondary Mycelium
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Primary Mycelium:
originates by the germination of the
uninucleate and haploid basidiospores.
It consists of many white, slender,
branched and septate hyphae.
The cells are uninucleate i.e.
monokaryotic
It is short lived and soon becomes bi-
nucleate (dikaryotic)
by hyphal fusion occurring between
cells of the hyphae of two apposite
(compatible) strains
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Secondary Mycelium:
It is subterranean, perennating,
and originates by the fusion of
two cells of the monokaryotic
mycelium.
The bi-nucleate or dikaryotic
cells by divisions and by clamp
connection form the secondary
or dikaryotic mycelium
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It ramifies in the bark tissues and
outer portions of the woody
cylinder.
The hyphae secrete enzymes which
digest the lignin of walls of the
wood cells.
Later it develops into the fruiting
bodies called basidiocarps.
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Basidiocarp:
The secondary mycelium collects in
hyphal knots
forms a small button like strand in the
bark of the wood.
these hyphal strands grow in size,
bursts through the bark surface of f
the tree and develops into basidocarps
(fruiting bodies.)
The basidiocarps may be sessile or
stalked
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stalk may be lateral or central
. height (stalk) -2-6″ , diameter -1/2
Black/Brown in colour
Stalks bear an umbrella shaped cap or pileus.
The pilues bracket or shelf like body with brown colour.
upper surface smooth /ridged surface.
undulating in concentric manner.
The concentric rings with alternate brown and white in
colour prominent in the peripheral regions of the pileus.
The lower surface of the pileus is without gills ,smooth
and flat,.
The pileus contains numerous small pores on under-
surface(characteristic feature ,therefore named as
polypore’s)
pores run deep into the tissues as hollow tubular canals.
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DIAGRAMATIC REPRESENTATION OF VERTICAL SECTION OF BASIDIOCARP
mature basidiocarp has four
visible regions
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i) Pileus Surface:
It is the upper surface of the
basidiocarp. smooth / incrusted.
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2. Context:
region between the upper surface of
pileus and the tube layer. region is
composed of anastomosing hyphae with
large intercellular spaces between them.
The hyphae are of three types:
Sometimes its upper region is soft and
lower region is hard then it is called as
duplex.
14. (a) Generative Hyphae:
Thin walled with dense cytoplasm, clamp
connections are present.
(b) Skeletal Hyphae:
Thick walled and un-branched.
(c) Binding Hyphae:
Thick walled but branched).
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THREE TYPES OF HYPHAE-GENRATIVE (A)
,BINDING (B) SKELTAL (C)
A
B
C
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3. Tube Layer:
This region consists of vertically placed
tubes attached to the lower surface of
the context.
4. Pore Surface:
It is the lower surface of the mature
basidiocarp. Tubes open at this surface.
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On the basis of the hyphae present in the fruiting
body, the basidocarps are differentiated into three
types:
(i) Trimitic:
All the three hyphae i.e. generative hyphae,
binding hyphae & skeletal hyphae are present e.g.
P. versicolor.
(ii) Dimitic:
Basidiocarps are made up of only two types of
hyphae-generative hyphae and binding hyphae
e.g. P. sulphureus.
(iii) Monomitic:
Basidiocarps consist of only generative hyphae
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Reproduction in Polyporus:
heterothallic.
Sex organs are absent.
In tube layer of basidiocarp in between the tubes
the tissue is made up of generative and skeletal
hyphae. It is called dissepiment.
From these hyphae arise short branches at right
angles at the length.
These branches develop into fertile basidia single
celled calavate and sterile paraphysis, cystidia and
setae also develope
These fertile and sterile structures form the inner
lining of the pores and collectively known as
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basidium is club shaped bi-nucleate sterigmata.
At maturity it projects slightly into the cavity of the pore
. The two nuclei of the basidium fuse to form the
synkaryon (karyogamy).
The diploid nucleus undergoes meiosis to form four
haploid nuclei.
Four short sterigmata develop from each basidium from
small.
basidiospores Oval and uninucleate ,borne on
sterigmata..
basidiospores are released from pores
after falling
on suitable substratum each basidiospore germinates
into a primary mycelium of plus or minus strain.