Kingdom Fungi – Sexual cycle of Fungus
Fungus sexual cycle involves the following three steps –
a) Plasmogamy- Fusion of protoplasm between two motile or non-motile gametes.
b) Karyogamy – Fusion of two nuclei.
c) Meiosis – Occurs in zygote resulting in haploid spores.
When a fungus reproduces sexually, two haploid hyphae of compatible mating types come together and fuse.
· In some fungi the fusion of two haploid cells immediately results in diploid cells (2n). However, in other fungi (ascomycetes and basidiomycetes), an intermediate stage called dikaryophase (2 nuclei per cell) occur.
· Later, the parental nuclei fuse and the cells become diploid. The fungi form fruiting bodies in which reduction division occurs, leading to formation of haploid spores.
The morphology of the mycelium, mode of spore formation and fruiting bodies form the basis for the division of the kingdom into various classes: