Sexual Reproduction in Rhizopus

Sexual reproduction in fungi happens through a process called conjugation, where two different types of hyphae—plus (+) and minus (-) strains—join together to form a new organism. This method helps fungi create genetic diversity and adapt to their environment.

Steps of Conjugation and Zygospore Formation

1. Hyphae Meet and Form Gametangia

When two compatible hyphae come close, their tips form special structures called gametangia. These contain many nuclei, cytoplasm, mitochondria, and stored nutrients. At first, each gametangium is separated from the rest of the hypha by a wall (septa).

2. Fusion of Gametangia

The walls of the touching gametangia break down, allowing the contents of both to mix. This process, called plasmogamy, combines their cytoplasm. Later, their nuclei fuse in karyogamy, forming a single zygote.

3. Formation of a Protective Zygospore

The zygote then develops into a zygospore, which has a thick outer wall. This wall helps protect it from harsh conditions like extreme temperatures and lack of food. The zygospore can stay dormant until conditions improve.

4. Germination and Spore Release

When the environment becomes favorable, the zygospore undergoes meiosis, a process that increases genetic diversity. It then grows into a sporangium, which produces and releases spores. These spores can land in a suitable place, germinate, and grow into new hyphae, restarting the cycle.

Why is Zygospore Formation Important?

• It helps fungi survive tough conditions.
• It creates genetic variety, helping fungi adapt.
• It allows spores to spread and grow in new places.

Conjugation in Rhizopus