Question

State the difference between planogametic copulation and gametangial copulation.

Answer 1

Hint: The fusion of two naked gametes(planogametes) is called planogametic copulation where one or both of these gametes are motile. Whereas, the gametangial copulation involves the fusion of the entire contents of two compatible gametangia.

Complete answer:
The reproduction of fungus takes place through the vegetative, fungus, and sexual methods. The process of sexual reproduction in fungi involves three distinct phases-Plasmogamy, Karyogamy, and Meiosis.
The process of fusion of protoplasts of compatible sex cells, as a result, they come close to each other is called plasmogamy. In Karyogamy, the fusion of two nuclei occurs to form a diploid zygote. In meiosis, the zygote undergoes meiosis(reduction division) to produce meiospores.

The two compatible nuclei brought together in the sexual reproduction of fungi by the following process:
PLANOGAMETIC COPULATION:
The fusion of two naked motile gametes i.e, plano gametes is called planogametic copulation. Three types of planogamy can occur in fungus based on their shape, and size of fusing gametes-Isogamy, Anisogamy, Oogamy.
 In Isogamy, fusing gametes are morphologically similar but physiologically they are two strains(- and + are the strains involved). It is a primitive type of reproduction, where the gametes are formed on different thalli.
In Anisogamy, the fusing gametes are both morphologically and physiologically different. Here, the male gametes are small and active, whereas the female gametes are large and less active when compared to male gametes.
In Oogamy, antherozoids(male gametes )are formed on specialized reproductive structures called antheridium. Oogamy is an advanced type of reproduction.

GAMETANGIAL COPULATION:
The karyogamy is established when the entire content of compatible gametangia fuses with each other. When the gametangia come in close contact, the wall at the point of contact dissolves, and their content mixes with each other. This happens in two ways:
It is the characteristic of some halocarpic form, where the passage of contents of one gametangium into the other through a pore developed in the gametangial wall at the point of contact.
The dissolution of the contacting walls of the two gametangia, which results in the mix of two protoplasts is how the direct fusion of gametangia takes place.
Other processes include Gametangial contact, Spermatization, Somatogamy.

Note: Plasmogamy, karyogamy, meiosis is responsible for the arrival of three mycelial phase-Telophase, Dikaryotic phase, Diplophase. In Telophase, the haploid mycelium(n) is formed as a result of meiosis. In the Dikaryotic phase, dikaryotic mycelium( n+n) is formed, as a result of plasmogamy. As a result of karyogamy, the diplophase mycelium(2n) is formed.