2. Order: Pucciniales (Rust fungi)
• Obligate parasites infect wide host range (identified by its sign, sori)
• Mycelium is simple, septate, branched, initially uninucleate and
later binucleate. Clamp connection is absent or rare.
• Binucleate uredospores represent the asexual spore (conidia).
Produced successively by the dikaryotic mycelium until the
environment is conducive, hence called as repeating spores
• Basidiomata are absent
3. • Produce distinct sex organs (spermagonia/ pycnia) and the
plasmogamy occurs through spermatization
• Teleutospores are binucleate only at the end of dikaryotic phase.
As the karyogamy and meiosis occurs only during
germination, they are referred as sexual spores.
They are thick walled, germinate to form septate
promycelium (=basidium) and bear four basidiospores.
4. • Teliospores are formed in a sorus called telium and may be sessile
(Melampsora) or borne on pedicels (Puccinia, Uromyces) or
in chains (Cronartium).
•Teleutospores may be single celled (Uromyces, Melampsora) or
two celled (Puccinia) or multicelled (Phragmidium) with a
range of surface ornamentations. They mostly undergo
dormancy (Puccinia graminis tritici) and hence called as
resting spores.
In some species, they germinate immediately without
dormancy (Puccinia xanthii, Puccinia horiana) and are
called leptospores.
5. Rusts are small raised reddish pustules on the leaves or leaf
sheaths, stem, usually of a rusty colour. The pustules may be either
compact or break through the host epidermis to become dusty.
E.g. Black rust stem rust of wheat -Puccinia graminis tritici
Rust of groundnut - P. arachidis
Rust of sunflower - P. helianthi
Rust of pearlmillet - P. substriata var. penicilliariae (P. penniseti)
Blackgram/ greengram rust -Uromyces phaseoli-typica
Bean rust - Uromyces appendiculatus
Coffee rust -Hemileia vastatrix
Linseed or Flax rust - Melampsora lini
6. Five stages of rust fungi
Stage 0: Spermagonia (Pycnia) with spermatia (pycniospores)
and receptive hyphae .
Stage I : Aecia with aeciospores
Stage II: Uredia with uredospores
Stage III: Telia with teleutospores
Stage IV: Basidia with basidiospores
7.
8. (a) Pycniospores Stage (0): Produced in a flask-shaped structure
called as pycnium. Periphyses and flexuous hyphae (receptive
hyphae) are present in pycnia. Pycnia are formed in the host after it
is infected by the basidiospores. Pycniospores are uninucleate of
either + or – type, single celled and behave as spermatia.
(b) Aeciospores Stage (I): Single celled, dikaryotic spores produced
in chains in cup-like structures known as aecia. Spores are yellow
to orange in colour with a hyaline characteristically verrucose wall.
9.
10. (c) Uredospores Stage (II): Single celled, binucleate, pedicellate
spores borne in uredia or uredinia. Uredospores are brown, oval
and echinulate. They behave as conidia and repeat several cycles
in a season and are also called as repeating spores.
11. (d) Teliospores Stage (III): Binucleate, pedicellate or sessile spores
producedin a sorus called telia in host tissue. They may be single
celled, bicelled or more than 2-celled with dark brown walls. They
produce basidium and basidiospores upon germination.
12. (e) Basidiospores Stage (IV): Haploid, unicellular spores borne
on sterigma. These spores arise from cylindrical to club-shaped 2
to 4 celled basidia.
13. Rust fungi that complete their life cycle in one host are termed as
autoecious (and the condition is called autoecism) and those
requiring two hosts for the completion of their life cycle are called as
heteroecious (and the condition is called heteroecium).
a. Autoecious rust: Five spore stages are formed on a single host.
e.g., Sunflower rust - Puccinia helianthi
Bean rust - Uromyces appendiculatus
Sunflower rust Bean rust Flax rust
14. b. Heteroecious rust: Two different hosts (viz., primary host and
alternate hosts) are required for completion of its life cycle.
Primary host is the plant where the teliospores are produced.
Alternate host is a plant, which is required to complete life cycle
without which the pathogen cannot survive.
Uredia and telia - primary host.
Pycnia and aecia - alternate hosts.
e.g., Wheat stem rust - Puccinia graminis var. tritici.
Wheat is the primary host and barberry is the alternate host.
15. Macrocyclic rust or Long cycled rust: Five spore stages are
produced in the life cycle of fungi.
a. Autoecious rust: Five spore stages are formed on a single host.
e.g., Sunflower rust - Puccinia helianthi
Bean rust - Uromyces appendiculatus
Flax rust - Melampsora lini
b. Heteroecious rust: Two different hosts (viz., primary host and
alternate hosts) are required for completion of its life cycle.
Wheat stem rust - Puccinia graminis var. tritici
(wheat – primary host; Barberry, Mahonia – alternate host)
Leaf rust of wheat – Puccinia recondita
(wheat – primary host; Thalictrum, Isopyrum – alternate host)
Bajra rust - Puccinia substriata var. penicillariae
(Bajra – primary host; Brinjal – alternate host)
16. Demicyclic rust
Uredial stage is absent. It produces only pycnia (sometime missing),
aecia and telia in host plant
e.g. Cedar apple rust - Gymnosporangium juniperi virginianae
(heteroecious rust)
Rubus orange rust – Gymnoconia pikiana (autoecious rust)
Cedar apple rust
17. Microcyclic rust or Short cycled rust
Complete its life cycle in a single host (autoecious rust).
Teliospore is the only binucleate spore produced in their life cycle.
Fungi which lack pycniospores and aeciospores are microcyclic rust
e.g., Jasmine rust – Uromyces hobsonii
Hollyhock rust - Puccinia malvacearum
Chrysanthemum rust - Puccinia horiana
Jasmine rust Chrysanthemum rust
18. Black or stem rust of wheat - Puccinia graminis tritici
Systematic position
Domain : Eukarya
Kingdom : Fungi
Phylum : Basidiomycota
Sub phylum : Pucciniomycotina
Class : Pucciniomycetes
Order : Pucciniales
Family : Pucciniaceae
Genus : Puccinia
Species : P. graminis tritici
19. Pathogen
Heteroecious rust
Primary host- wheat; Alternate host- barberry (Berberis vulgaris)
Alternate host
Stage 0 - Pycnia and pycniospores
Stage I - Aecia and aeciospores
Main host
Stage II - Uredia and uredospores
Stage III - Telia and teleutospores
Plant debris
Stage IV - Basidia and basidiospores
20. Symptoms
Reddish brown pustules (raised blisters) are produced mostly on the
stem and also on leaves. Later they merge and form linear lesions.
Late in the season linear, black telia are formed in the same
uredosori or on a separate place; severe infection causes drying of
leaves.
Uredosori Teleutosori
22. Pathogen
Pycnium Flask shaped, ostiolate (spermagonium)
Pycniospore Spherical, thin-walled, hyaline, unicellular, uninucleate
Aecium Cup like and thick walled
Aeciospore Unicellular, yellow, hexagonal, thick walled,
binucleate, echinulated.
Uredium/ Uredosori
Uredospore Oval, single celled, binucleate, golden brown, thick
walled, echinulated, pedicillate (repeating spores)
Telium / Teleutosori
Teleutospore Two celled, dark brown, thick walled apex with
pointed at the tip with slight constriction at the
septum (resting spore), Young teleutospores are
binucleate at maturity it has a single diploid nucleus
Basidium or promycelium – Long thin walled, hyaline and 4 celled
Basidiospore Unicellular, round and uninucleate
23.
24. Rust of pearlmillet - Puccinia substriata var. penicillariae (P. penniseti)
Symptoms: Appears on lower and older leaves as typical erumpent
pustules containing a reddish, brown powder (uredospores). As the
leaves senesce dark brown teliospores are produced. Heteroecious
rust. Primary host is pearlmillet and the alternate host is brinjal
26. Rust of blackgram /greengram - Uromyces phaseoli-typica
(syn. U. appendiculatus)
Systematic position
Domain : Eukarya
Kingdom : Fungi
Phylum : Basidiomycota
Sub phylum : Pucciniomycotina
Class : Pucciniomycetes
Order : Pucciniales
Family : Pucciniaceae
Genus : Uromyces
Species : U. phaseoli-typica
27. Symptoms
Appears first on leaves as small, round or oval, cinnamom brown,
powdery pustules and coalesce. These pustules occur rarely on both
the surfaces but more frequently on lower surface.
28. Pathogen
Autoecious macrocyclic rust.
Uredospores are globose, single celled, echinulated,
pedicellate, golden brown with two equatorial germ pores.
Teliospores are single celled, smooth walled, globose, chestnut
brown, pedicellate and with hyaline papilla.
Pycniospores are hyaline and spherical
Aeciospores are hyaline and elliptical with minute verrucose
markings
Pea rust caused by Uromyces fabae and Uromyces pisi
Bean rust caused by Uromyces appendiculatus
31. Leaf rust of coffee – Hemileia vastatrix
Systematic position
Domain : Eukarya
Kingdom : Fungi
Phylum : Basidiomycota
Sub phylum : Pucciniomycotina
Class : Pucciniomycetes
Order : Pucciniales
Family : Incertae cedis
Genus : Hemileia
Species : H. vastatrix
32. Symptoms
Infection is restricted to leaves but rarely seen on tender shoots
and berries
Pustules appear as small yellowish spots, 1-2 mm in dia. Later
they become orange coloured and increased in size.
On upper surface, the colour is often brownish.
The infected leaves are defoliated which affects the yield.
33. Life cycle
The uredospores are orange segment like with convex surface
ornamented with spines or warts. The fungus occasionally
produces teliospores which are turnip shaped and germinate to
produce basidium and basidiospores. They do not infect coffee or
any other host. No alternate host has been reported.
Uredospores Teleutospores
