social pharmacy d-pharm 1st year by Pragati K. Mahajan
PAT 212 L 4-1.ppt pathology pests and diseases
1. PAT 212
L 4. Mode of Nutrition and
Reproduction of Fungi
2. NUTRITION OF FUNGI
• Fungi are chemoorganotrophs. i.e derive energy by
organic compounds.
• Unlike animals which are also chemoorganotrophs,
fungal absorption is absorptive.
• Ingestion is rare and restricted only to the slime
moulds.
• Fungi need about 17 elements.
• Calcium, which is an essential macro element for green
plants, is needed in traces or not at all by fungi.
3. • Among monosaccharides, xylose glucose and
fructose support good growth of largest number of
fungi.
• There are some fungi, which do not utilize glucose.
• Disaccharides, sucrose, maltose, cellobiose and
lactose are first broken by extra cellular hydrolytic
enzymes and the component sugars are then
absorbed.
• Except lactose, other disaccharides are good sources
of carbon.
4. • Among polyaccharides, cellulose degradation by fungi is
important for maintnance of the carbon cycle.
• It is a polymer of beta glucose units joined by b 1-4 glycosidic
linkages.
• There are five types of cellulolytic enzymes viz. endoglucanase,
exoglucanase, cellobiase, oxidative cellulases, and cellulose
phosphorylase.
• The three main enzymes endoglucanase, exoglucanase and
cellobiase by their sequential, synergistic and cooperative action
bring about total breakdown of cellulose to beta glucose.
5. Pectic substance the most complex
macromolecules in nature are made of five
polyaccharides.
These are,
• Galacturonans
• Rhamnogalacturonans
• Arabinogalactan I
• Arabinan
• Arabinogalactan II
• They are collectively form the pectic polymer
structure.
6. • This is a pectic backbone comprising HG
(Homogalacturonans) and RG I (Rhamnogalacturonans)
regions.
• The RG I bars several side chain viz. HG, RG II, arabinan,
AG I, AG II, XGA and is called hairy region.
• The HG is called smooth region.
• The types of side chain and their arrangements on the RG
I region vary with pectin sample.
• Pectolytic enzymes degrade the homogalacturanan i.e the
“smooth region” of the pectic macromolecule.
7. • The enzymes are broadly classified into two broad
categories, the chain modifying enzyme (PME) and chain
splitting or depolymerizing enzymes (glycosidases and
lyases).
• PME hydrolytically removes the methyl group.
• Chain splitting enzymes break the α-1,4 glycosidic bonds,
forming smaller fragments, and ultimately releasing
galacturonic acid residues.
• Their nomenclature is based on the preference of the
substance (pectin or pectic acid) and site of split.
8. • Starch is a good carbon source for majority of fungi and is
often better than glucose possibly due to the presence of
some glucose factors, that usually accompany some native
starch.
• It is a complex polymer made of alpha glucose units and can
also be said to be made of maltose units.
• It consists of un branched portion, amylose (20-25%) and rest
of branched portion amylopectin.
• There are two types of extracellular enzymes that degrade
starch, α and β amylase.
9. • The alpha amylase attacks the glycosidic linkage
randomly to produce shorter chains, are called
dextrins.
• While beta amylase acts terminally releasing
maltose.
• Maltose is then acted upon by maltase releasing
glucose.
• Chitin the polysaccharide of N- acetyl glucosamine
units is degraded by an extra cellular chitinase.
10. • Fatty acids are generally utilizable, but are toxic to some
fungi.
• However, Leptomitus lacteus and Apodachlya sp. which
fail to grow on sugars, including glucose, utilizes fatty
acids avidly.
• Cutin the main component of cuticle of plants, is a
polymer of C 16 and C 18 hydroxy fatty acids joined by
ester bonds and some peroxide bridges and ether
linkages.
• These are degraded by cutin esterase and carboxin cutin
esterease
11. • The former hydrolyses the ester bonds releasing
monomers C 16 and C 18 hydroxy fatty acids, while the
latter hydrolyses the peroxide group.
• Fungi derive their nitrogen requirements from inorganic,
as well as, organic sources.
• Fungi usually derive their sulphur requirments from
sulphate ions.
• Phosphorous, potassium and magnesium are taken in
organic form.
• Calcium is required in traces or not at all.
12. • Vitamin requirements of fungi are only for water
soluble vitamins.
• Eg: vitamins of B group(vitamin B1 or thiamine, B2
or riboflavin and B6 or pyridoxine) and vitamin H
(biotin).
• Most common deficiency is for thiamine followed
by biotin.
• The deficiency is more common in yeasts.
• Fungi rarely needs external riboflavin, ascorbic
acid and folic acid.
13. • Fungi are used as test organisms for bioassay of
vitamins.
• Phycomyces blakesleeanus, and Phytoiphthora
(all species) are used as bio assay of thiamine
pyridoxine and pantothenic acid assay employs
Saccharomyces carlsbergensis. S. cerevisiae is
used for the assay of biotin.
14. TYPES OF PARASITISM
• The relationship between the parasite and the
host is called as Parasistism.
• Based on the source of nutrition, the fungi may
be classified as
• Parasites
• Saprophytes
15. PARASITES
• Parasites may be classified as
1.Obligate parasites
2.Facultative parasites
3.Facultative saprophytes
1)Obligate parasites
• These are parasites which cannot be grpwn on
dead or artificial food and need living host to
complete their entire life cycle.
– It is also called biotrophs. Eg. Rusts, Mildews, Viruses.
16. Hemibiotrophs.
These pathogens attack living tissues and grows in or on
them in the same way as that of biotrophs the tissue is dead
but continue to grow and reproduce after the tissue is dead.
Eg. Leaf spotting fungi.
1) Ectoparasite.
The parasite may be live on the external surface of the
host. Eg. Erysiphe polygoni.
2) Endoparasite
The parasites may grow inside the host cell (intracellular)
or in between the cells (inter cellular) of the host plant and
draw nutrition. Eg. Leveilulla taurica
17. 3) Destructive parasite
Those which draw nutrition from the host and
often destroy or kill the host are called destructive
parasite.
• Eg. Root rot, wilt causing pathogens
4) Balanced parasites:
Those which draw nutrition without
killing the host are termed as balanced parasite.
18. Saprophytes
Any organisms living on dead organic
matter.
Facultative parasites.
These are the organisms which are usually
saprophytic in their mode of life but under certain
conditions they became parasites.
Eg: Pythium, Fusarium etc.
19. Facultative saprophytes:
These are the organisms which are usually
parasites in their mode of life but under certain
conditions they became saprophytes.
Eg: Smuts, Phytophthora, Venturia inaequalis,
Sphacelotheca sp.
Necrotrophs:
A parasite is called nectrotroph when it kills
the tissue in advance of penetration and then
live saprophytically. Also called perthotrophs.
20. • They are so called less specialized parasite which can
cause immediate and severe damage to their host
tisssue.
• Eg: Sclerotium rolfsii, Venturia, Claviceps,
Phytophthora.
SYMBIOSIS
• The relationship of two dissimilar organisms living together
in close association for mutual benefits also called
mutualism.
• Eg: lichens – close association of fungus and algae.
22. • In all the three types, the hyphae of the
fungal symbionts permeate the soil and
obtain scarce and relatively immobile
nutrients espescially Phosphorous but also
Nitrogen, Potassium, Cu, Zn and supply
more effectively to the plants then the root
hairs of the concerned plant
23. Synergism
The ability of two kinds of organisms to grow better or
produce greater effect conjointly than either one could alone.
Eg. Diplodia natalensis and Colletotrichum gloeosporioides
together produce much greater effect on citrus bark than either
one of the pair alone can produce.
Commensalism
In commensalism one of the partner profits living
together with a second species, but the latter receives neither
good nor harm from the organism it favors.
Eg: Penicillim digitatum is responsible for the stimulation
of the fungus Diplodia natalensis in citrus
24. • Amensalism
A microbial community supports high density of
dissimilar populations that are characterized by
interactions detrimental to many of the inhabitant.
This process is called Amensalism.
Eg: When urea fertilizer applied to the soil; the
soil inhabitant fungi convert it into ammonia which
results in an increased pH. Ammonia is further
oxidized into nitrite which in turn checks
population of Fusarium oxysporum
26. Fungi
Thallus: Vegetative body of the fungus. It
consists of elongated continuous tubular or
hallow filamentous structure. This individual
filament is called Hypha
Mycelium: Collection of hyphal bodies are
called mycelium
Septate mycelium
Aseptate or Coenocytic mycelium
28. Reproduction
• Vegetative – modification of hyphal cell or
mycelium
• Asexual- No union of male and female
gametes
• Sexual- Union of male and female
gametes
29. Sexual reproduction in fungi
Union of two nuclei consists of three phase
Plasmogamy: Fusion of two protoplast which
bring s two haploid nuclei close together in the
same cell
Karyogamy: Fusion of two nuclei
It follows plasmogamy immediately
In many fungi, this pahse is delayed which results
in the formation of dikaryon
Meiosis and follows nuclear fusion
30. Sexual spores
• Fusion of male and female gametes of opposite
sex
• functions as resting spores
• Pass through dormant period before germination
• Oospores, Zygospores, Ascospores, Basidispors
31. Monoecious Vs Dioecious
• Monoecious: Both sexes occur in same thallus
• Dioecious: Sexes occur in different thalli
32. Homothallic Vs Heterothallic
• Homothallic : Every thallus is self fertile and
can be reproduced by itself
• No dioecious fungi can be homothallic
• Eg: Volvariella volvaceae
• Heterothallic: They are self sterile and Two
separate thalli are required for sex reproduction
• Eg: Mucor, Rhizopus
33. Gametes vs Gametangia
• Sex cells are called gametes and mother cell is
called gametangia
• Isogametes (when the male & female gametes
look alike)or isogametangia
• Heterogametes or heterogametangia (when the
male & female sex organs look distinctly
different)
• Heterogametes: Male : Sperm ; female: Egg or
oosphere
• Heterogametangia: Male : Antheridium
Female : Oogonium
34. Methods of sexual reproduction
1. Planogametic conjugation
2. Gametangial contact
3. Gametangial copulation
4. Spermatization
35. 1. Planogametic conjugation
• Male and female gametes are motile
• Common in aquatic fungi
• Iso planogametic conjugation:
morphologically similar gametes fused together
• Eg: Synchitrum endobioticum
40. 2. Gametangial contact
• Gametes reduced to undifferentiated protoplast and
they are not released outside
• Two gametangia of opposite sex come in contact
• One or more gamete nuclei from male gametangium
migrate into female gamatangium through
fertilization tube or pores
Eg: Pythium aphanidermatum, Erysiphe polygoni
44. 3. Gametangial copulation
• Two gametangia completely fuse with one
another
• Entire content is fused
• Mucor, Rhizopus
45. 4. Spermatization
• Spermatia carried by wind or insect or water
fused with receptive hyphae of female
gametangium
• Spermatia: minute, uninucleate, non motile spore
like male structures
• Puccinia graminis var tritici - Wheat rust
46.
47. 5. Somatogamy
• No sex organs are produced
• Somatic cells function as gametes
• Ascomycotina ; Basidiomycotina fungi
48. Fructifications and fruiting bodies
Asexual fruiting bodies
1. Acervulus/ Acervuli
Saucer shaped asexual
fruiting body contains short
conidiophores which bear
single celled , hyaline sickle or
cylindrical shaped conidia and
conidiophores are intermingled
with black long hair like
structures called setae
Eg. Colletotrichum
Produced by mitosporic
fungi of the form order
Melonconiales
(Deutromycota
Coelomycetes)
49. 2. Pycnidium
Asexual fruiting body
produced by mitosporic
fungi in the form order
Sphaeropsidales
(Deuteromycota,
Coelomycetes). It is
often spherical or
inversely pearshaped
(obpyriform) and its
internal cavity is lined
with conidiophores.
Macrophomina
Phoma
Phomopsis
Botryodiplodia
Diplodia
50. 3. Sporodochium/ Sporodochia
A small, compact
cushion like structure
produced by mitosporic
fungi belongs to
Tuberculariales
(Deuteromycota,
Hyphomycetes). This
stroma bears the
conidiophores on
which conidia are
formed
Eg: Fusarium
51. 4. Synnemata or coremium
• Compact or fused,
generally upright
conidiophores, with
branches and spores
forming a headlike
structure
• Eg: Arthrobotryum
52. Sorus
• Spores or sporophores
are grouped into large
masses or clusters which
may be naked or covered
by host epidermis
• Eg: Puccinia , Uromyces
Hemileia
53. Sexual fruiting bodies
Sexual fruiting bodies produced by
Ascomycotina and Basidiomycotina fungi
Ascomycotina: Ascocarp
Basidiomycotina: Basidiocarp
54. Types of Ascocarp
1. Perithecium
• Asci are enclosed in a flask shaped fruiting
bodies with ostiole
eg. Claviceps,
Ceratocystis
55. 2. Cleistothecium
• Completely closed ascocarp
• No ostiole
• Asci are scattered ( Penicillium) or arranged
basally ( Erysiphe)
56. 3. Apothecium
• Open disc like ascocarp with concave or convex
structure
• Sclerotinia sclerotiarum
57. Ascostroma
An ascocarp resembling a
perithecium but whose
asci are not regularly
organised into a
hymenium and are
bitunicate, having a
double wall which
expands when it takes up
water and shoots the
enclosed spores out
suddenly to disperse
them
Venturia inaequalis
58. Basidiocarp
Large fruiting body of
the basidiomycotina
fungi in which
basidiospores are
produced on a club
shaped basidium.
Mostly epigeous and
rarely hypogeous
Epigeous: Mushroom
and bracket
Hypogeous: Truffles
