Puccinia graminis is a fungus that causes black stem rust disease on wheat and other grass crops. It has a heteroecious life cycle requiring two hosts, wheat and barberry plants. On wheat, it produces urediniospores that spread the disease and later teleutospores which overwinter. Teleutospores produce basidiospores on germination which infect barberry plants. On barberry, it produces pycniospores and then aeciospores which infect wheat to complete the life cycle. The disease symptoms and stages on both hosts are described in detail in the document.

1. Puccinia graminis
KINGDOM FUNGI

2. symptoms on wheat and barberry host

3. Introduction
 It has many species that are obligate parasite
 Puccinia graminis is a common on wheat and
other grasses like oat, barley , rye etc.
 Fungus is called as heteroecious host
because it completes its life cycle in two host
 It has 5 stages, which will be discussed in
next slides
 wheat is called as primary and barberry plant
is called as secondary host

4. Stages of Puccinia
 Uredia bearing uredospores.
 Telia bearing teleutospores.
 Promycelia bearing basidiospores
 Spermogonia bearing spermatia and receptive hyphae.
 Aecia bearing aeciospores.

5. Life cycle on wheat
plant
Uredosori
It caused black stem rust and
symptoms appear in early
March in the form of elongated
, reddish sori or pustules. These
are called a7s uredosori

6. 1: Uredinal stage
1. They are one celled, bi nucleated ,
globoose, and thick walled spores
2. Produced on the stalks
3. By applying pressure on host
epidermis , they cause breakage
and form uredinia. Thus the stage
is called uredinal stage

7. Dispersal and
germination of
uredospores
• Enters through stomata
• Appresorium ( welled vesicle at tip)
formation takes place
• Nucleus migrates into appresorium
and then septum is formed
• Hyphae spreads and with the help of
haustoria it takes its nutrition

8. Teleutospores
1. uredospore change their colour and
converted into brown to dark red or rust
colour.
2. These are due to teleutospore
3. They are two celled and thick walled,
oval and binucleated
4. They a have one germ tube and two
nuclei
5. They are dispersed by wind and do not
immediately cause disease but can
withstand for unfavourable condition
and survive for long

9. 1. Upon germination of teleutospore, each
germ tube form a probasidium or
epibasidium.
2. Both nuclei fuse to form a dikaron and
after meiosis produces 4 haploid nuclei
3. After this the content move into and
formation of septum take place
4. Epibasidium produces lateral Sterigmata
and each form basidiospore
5. These are disperse by wind
Basidial stage

10. Life cycle on barberry
plant
Germination of basidiospore
1. They are not able to infect wheat plant but
they cause infection to another host called
barberry plant
2. Upon lodging on barberry plant, these
basidiospores form short germ tube and
enters host epidermis .
3. The hyphae ramify ( branches) and
become intercellular
4. Nutrition is obtained by haustoria formation

11. Pynidial stage
• After about four days of the infection
• dense mats both beneath the upper and lower
epidermis are formed
• Hyphae produced through germination of
basidiospore is monokaryotic and it forms small
knots
• Below the upper epidermis
• These are then transformed into flask shaped pynidia
or spermatia
• The opening of spermatia is called ostiole
• Numerous uninucleated spores are produced in
these spermatia
• There are also paraphysis that come out and act as
receptive hyphae
• The spermatia come out through ostiole with
mucilage liquid and are dispersed by insects

12. Dikaryotization
Spermatium get attached with
receptive hyphae of oopossite
strain and its nucleus enters , after
fusion it become dikaryotic

13. Aceial Stage
1. In spermatium the nucleus divides
several times and migrate to other nuclei.
2. These dikaryotic cells foirm group of cells
below the at lower epoidermis .
3. These binucleated cells divide
transversely and form chain of cells
4. Each cell divide to form larger and
smaller cell
5. Larger cell is transformed in to
aeciospore.
6. Some cells are transformed to form a
wall called peridium.

14. Dispersal of aceiospore
When spore matures, the wall of the
peridium ruptures and cup shaped
structure called as acedium and
aciospore are released.
Each spore is unicellular , binucleated
and generally rounded in shape.
They are dispersed by wind.

15. Acidial cup and acidial spore

19. Related you tube video links
https://www.youtube.com/watch?v=72ufVf04cuU