In this article we will discuss about the asexual and sexual reproduction of rhizopus.
Asexual Reproduction of Rhizopus:
1. It takes place by spores formed in the sporangium.
2. A single sporangium develops at the tip of long, erect sporangiophore.
3. A dome-shaped columella (Fig. 77) is present in each sporangium. The protoplast of columella is in continuation with that of sporangiophore.
4. The space between columella and wall of sporangium is known as spore sac. It remains Filled with sporangiospores or aplanospores.
5. Each sporangiospore is ovoid, non-motile, unicellular and multinucleate structure. There is no flagella on the spores.
6. Spores come out on dehiscence of sporangium and germinate immediately by forming new mycelium.
7. Another means of asexual reproduction is the formation of chlamydospores.
Sexual Reproduction of Rhizopus:
1. It takes place by the fusion of multinucleate gametangia. Species are dioecious or heterothallic.
2. Two fusing gametangia (male and famale, or + and -) are morphologically similar but physiologically different.
3. Developing gametangia are known as progametangia. These are filled with cytoplasm and nuclei in their swollen tip.
4. At the time of their fusion each gametangium is separated from the ‘suspensor’ with the help of a septum.
5. The multinucleate protoplasm of each gametangium is known as coenogamete (Fig. 78).
6. Fusion of two gametangia takes place. The nuclei of + gametangium fuse with those of -, and thus many diploid nuclei are formed. Around this fusion product, a thick, spiny wall develops, and now it is called zygospore.
7. Zygospore germinates meiotically by producing a long sporangiophore bearing a sporangium at the tip.