Question

Differentiate between gametangial contact and gametangial copulation.

Answer 1

Hint: Two types of sexual reproduction in fungi based on whether the male and female gametes fuse after fertilization or not.

Complete answer:
Sexual reproduction in fungi involves the union of two compatible nuclei. The sex organs of fungi are called Gametangia.
Gametangial contact refers to sexual reproduction where the gametangia of two different sex do not fuse or loose there identity. It basically involves a direct transfer of male gamete nuclei to the female gametangium through a pore developed after contact of two gametangia of the opposite sex by the dissolution of the gametangial walls at the point of contact. In some species, the pore formation is replaced by the development of a fertilization tube that serves as a passage tube for the male nuclei into female gametangium.
Gametangial copulation is characterized by the fusion of both the sex gametangia and this happens either in one of the two ways:
i) Through the passage of one sex gametangium contents into the other sex gametangium through a pore developed at the point of contact in gametangial walls. Typically seen in some holocarpic form in which the entire thallus acts as a gametangium, thus male thallus attaches itself to female thallus and transfers its entire content into a female thallus.
ii) Through direct fusion wherein dissolution of the contacting walls of the two gametangia, resulting in a single cell in which the two protoplast mix.

Additional Information:
- Sexual reproduction in fungi involves 3 phases:
a. Plasmogamy: the union of two protoplasts, bringing the two nuclei together in a single cell. If the two nuclei are of two different sex then they are called a dikaryon.
b. Karyogamy: Fusion of the nuclei brought together by plasmogamy.
c. Meiosis: restores the haploid condition in four nuclei.
- Different fungi based on sex organs involved in reproduction:
a. Hermaphroditic: these species produce distinguishable male and female sex organs on each thallus. A single thallus of hermaphroditic species can reproduce sexually by itself if it is self-compatible.
b. Dioecious: these species consist of only male or female thalli that is they either prepare only male sex organs or female sex organs. These species cannot reproduce sexually by itself because it is either male or female.

Note: Fungi reproduce by vegetative, asexual, and sexual methods. Sexual reproduction takes place in all groups of fungi except Deuteromycetes.