Chytridiomyco these organisms, commonly called "chytrids", are aquatic or live in damp soil. Many are parasitic on algae, fungi, mosses, and higher plants




Дата канвертавання17.04.2016
Памер10.18 Kb.
Lecture No.8
Phylum: CHYTRIDIOMYCO
These organisms, commonly called "chytrids", are aquatic or live in damp soil. Many are parasitic on algae, fungi, mosses, and higher plants.

The primitive Members of the division Chytridiomycota have unicellular form (entirely converted into a reproductive sporangium) while the higher have both broad true hyphae and narrow rhizoids. Their cell wall composition is mostly chitin, and cellulose is not known to occur. This division has been classified with the true fungi even though flagellated spores and gametes are produced. Gametes and zoospores have a single, posterior whiplash flagellum. Sexual reproduction is variable and may be isogamous, anisogamous or oogamous. The division has a single class, the Chytridiomycetes

Order: Chytridiales

thallus in this order is commonly unicellular and may have limited hyphal growth [assimilative rhizoids and a sporangium (eucarpic) ] but is not considered to be mycelial. Hyphal cells are coenocytic except where there are reproductive structures. The Chytridiales are thought to be the most primitive members of the Chytridiomycetes







Synchytrium endobioticum :

An obligate parasite which causes black wart disease of potatoes. Like many other specialized parasites it induces abnormal growth (hypertrophy) of the infected cells. The infected tubers have large wart-like growths on them. S. endobioticum produces thick-walled resting spores in the warted tuber. Also it forms zoospores which have a very short range of operation in the aqueous phase of the soil. Synchytrium sp. developing zoosporangium on a leaf, and the resting spore (overwintering spore) in a potatoe tuber. The genus is unicellular, holocarpic (whole cell becomes a reproductive structure). The sexual cycle is initiated when some zoospores function as gametes. The gametes are morphologically similar but differ slightly in behavior.



The knowledge that Chytrids parasitize pollen grains will be exploited in this lab. We will be using pine pollen as bait for these fungi. The purpose of baiting is to increase the population of fungi so that they can be studied in conditions closely resembling their natural state.

Procedure:

Place a small amount of dried Lake soil into the finger bowl. Cover the soil with Lake water until the finger bowl is approximately two thirds full. Sprinkle a fine dusting of pine pollen on top of the water. Partially cover the finger bowl with plastic wrap, label it, and leave it for about twenty-four hours. After twenty-four hours, check the pine pollen for infection. With a pipette, take up some of the water, making sure to capture some pine pollen grains. Empty the pipette onto a glass slide and cover the sample with a cover slip. Observe the slide under the microscope. You are looking for pollen grains with round capsules on them. The capsules contain many zoospores.





База данных защищена авторским правом ©shkola.of.by 2016
звярнуцца да адміністрацыі

    Галоўная старонка