In this article we will discuss about the asexual and sexual reproductive structures of aspergillus.
Asexual Reproduction of Aspergillus:
1. It takes place by the formation of conidia on conidiophores.
2. From the prostrate somatic mycelium arise many erect, thick-walled, aseptate and unbranched hyphae called conidiophores.
3. Thick-walled cell, from which a conidiophore arises, is termed as foot cell.
4. The tip or apex of the conidiophore becomes globular or swollen, and is known as vesicle.
5. Vesicle is multinucleate structure, and gives rise to many sterigmata or phialides, which cover its complete surface (Fig. 84).
6. Each sterigma is multinucleate, finger-shaped or bottle-shaped structure.
7. Sometimes, a second layer of sterigmata also develops on the upper side of primary sterigmata. These are called secondary sterigmata (Fig. 84B);
8. Each secondary sterigma (or primary sterigma if there is no secondary sterigma) gives rise to many, small, rounded and multinucleate conidia arranged basipetally. But in some of the species conidia are uninucleate.
9. A mature conidium is globose, black, brown or green-coloured, thick-walled structure, and the wall is differentiated into outer spiny epispore and inner smooth endospore.
10. Each conidium germinates by producing a germ tube.
Sexual Reproduction of Aspergillus:
1. Sexual reproduction takes place by the formation of antheridium and ascogonium.
2. Ascogonium is a multinucleate, elongated female structure having a terminal trichogyne.
3. Fruiting body is of cleistothecium type (Fig. 85).
4.In rich fruiting body develops many asci.
5. Each ascus contains eight uninucleate ascospores.
6. Ascospore germinates and produces new hapiomyceliunt.