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Puccinia graminis

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.

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Puccinia graminis KINGDOM FUNGI
symptoms on wheat and barberry host
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
Stages of Puccinia  Uredia bearing uredospores.  Telia bearing teleutospores.  Promycelia bearing basidiospores  Spermogonia bearing spermatia and receptive hyphae.  Aecia bearing aeciospores.
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
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
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
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
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
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
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
Dikaryotization Spermatium get attached with receptive hyphae of oopossite strain and its nucleus enters , after fusion it become dikaryotic
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.
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.
Acidial cup and acidial spore
Related you tube video links https://www.youtube.com/watch?v=72ufVf04cuU