Agaricus campestris common gilled fungus or mushroom which grows in soil rich in humus. It has large fruitification of sporospore which looks like umbrella.
Structure of Reproduction:
According to somatic structure the plant body of mushroom can be divided into main parts.
(i) Vegetative mycelium or Rhizomorph and
(ii) Fruitification or sporophore.
(i) Rhizomorph: This remains hidden in the soil. It is formed of finally divided mycelium and hyphae which form network of threads in the soil. The hyphae are septate and hyaline and contain oil globules, vacuoles and Protoplasm. The cell of hyphae is haploid and uni-nucleate. Numerous mycelia twist together to form a cord like rhizomorph. The dikaryotic mycelium branches further and replaces monokaryotic mycelium. These dikaryotic mycelium produce aerial fruiting bodies year after year.
(ii) Sporophore of Fructification:
It is aerial and occurs above the soil. It begins to develop as a tiny dense kind underground dikaryotic hyphae forming rhizomorph. In the beginning sprophore appears like elliptical button hence formed as button stage. Afterwards constriction appears in button which becomes more and more prominent, takes the form of cavity or chamber known as gill chamber or prelumell or cavity. From the root of this gill cavity are differentiated the gills. The dome is distended to from cap like pileus. The button is carried upward by rapid elongation of remaining hyphae which form the stem, stalke of stipe. Margin of button is partial or inner veil. By further elongation of stalk the button projects above the soil and enlarges in size. Growths proceeds rapidly at upper portion of bottom and slow at lower portion. The button opens into an umbrella like Cap or pileus at the same time inner veil which covers lower surface of pileus ruptres.
Mahire fleshy umbrella shaped basidiocarp. Sporophore or fructification of Agarcius. Consists of thick stalk like stipe bearing the cap like pileus at the top. From the under surface of pileus long thin plates called gills or lamellae radiate from margin of plieus to the stipe.
Structure of gill: Gills are situated in chamber, Gills are flesh coloured or pink in young condition and dark brown in mature conditions. Each gill is lined by a spore bearing layer the hymenium. Trama is central portion of gill with mass of long hyphae. The hyphae of trama bend outwards on both surfaces of gill and terminate in a layer of small rounded cells and are termed sub hymelium, outside of which is layer of hymenium. This region has basidia which are bi-nucleate end of basidia, two or four sterigamata are developed and a single basidiospore is developed on each sterigma.
Basidiospores:- Basidia are club shaped and binucleate. Two nuclei of different strains fuse together and a fusion nucleus is formed in each basidium. The fusion nucleus is divided by reduction and mitotic division and form four haploid nuclei. For small tube like structures the sterigma develop on each basidium. Daughter nuclei pass down into sterigmata and then one basidiospore is formed at the top of each sterigmata out of four basidiospores two are of (+) strain and two of (-)strain.
Each basidiospore after liberation by wind to long distance germinates in monokaryotid haploid mycelium in favourable condition.
(4) Pycnidiospores:- Basidiosores which are unable to infect the wheat plant fall on the leaves of Berberis vulgarin. Each basidiosporeon germination form a primary hypha which penetrates into leaf cells and froms separate uninucleate monoploid branched myucelium. Few day after infection their monokaryotic mycelium results into formation of pseudoparanchymatous mass of tissue which forms pychidia or pynidial cup or spermatogomia. Few slender hyphae develop from this pycnidia which are uninucleate and are called sporophore. Nucleus of sporophore divides and one daughter nucleus after each division more towards the apex and transforms into a pycnidiospore.
Pynidiospore and formed in chains. Each pycnidiospore is a circular or oval thin walled structure. By the rupture of epidermis the pycnidiospores are liberated. Point of rupture is called as ostiole. Pycnidiospores are male sex organs which come out from ostiole. From the inner side of spermatogonial wall or pycnidiospore wall arise a large number of hair like sharp pointed periphysis. These project out by ostiole. A number of longer cylindrical and unbranched or branched hyphae with blunt tips arise just beneath or amont periphysis. They are respective hyphae or flexous hyphae and represent the female sex organs. They protrude through the ostiole.
(5) Accidiospore:- Monokaryotic mycelia which form pycnidiospores at the upper surface of leaf develop accidial cups on lower surface. The primary mycelium collects in patches near the lower epidermis of leaf and are known as protoaccidium. Due to the stimulus of sexual act the protoaccidium develops into a cup shaped accidium, from the bottom of which arise closely packed parallel chain of accidiospores on the side towards the lower epidermis. During the development of accium a basal layer of dikaryotic cells is differentiated nuclei travelling down the respective hyphae migrate from
Cell to cell of the primary mycelium through spectral perforations reach the basal cells of protoacecuim and thus dikaryotise them. These dikaryotia cells multiply and form the hymenium of aecidial cup while as subhymemium is formed of monokaryotic cells. A few sporophores emerge from dikaryotic hyphae which for a chain of binucleate or dikaryotic spores called as accidiospores, on maturation of aecuim spore chains push through the host epidermis and then by roof of pyridium, spores are thus exposed and dispersed by wind. The accidiospores are binucleate, subglobase to hexagonal, light orange yellow and with six germ pores. Aecidiospores from Barberry plant are carried by air to plans and infect the wheat plant on wheat plant the germ tube of accidiospores penetrate by stomata and gives side to dikaryotic mycelium from which urediospore arises. Thus the life cycle of fungus is completed.
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