Both asexual and sexual reproduction take place in fungi and there is no sexual reproduction in imperfect fungi.
Spores are haploid, non-motile and are produced in very large number. Water is not needed for the dispersal of spores.
Spores are dispersed by wind. Thus, spores are widely distributed. Spores may be dispersed by insects and small animals under favorable conditions. Spores germinate and give rise to new fungal hyphae.
Conidia are not inside the sporangia and usually form a chain or cluster. Conidia are produced in large number and can survive for weeks.
During sexual reproduction hyphae of two genetically different but compatible mating types come together, their cytoplasm fuse followed by nuclear division.
In Basidiomycetes and Ascomycetes, fusion of nuclei i.e; karyogamy does not take place immediately after the fusion of cytoplasm i.e; plasmogamy: The two genetic types of haploid nuclei from two individuals may coexist and divide in the same hyphae for most of the life of the fungus and such a hyphae that contain paired haploid nuclei is said to be n+n or dikaryotic or heterokaryotic.
When the nuclei fuse the zygote undergoes meiosis prior to formatin of spore. Fungus spores germinate directly into haploid hyphae.
Different fungi group produce different types of haploid sexual spores. Basidiospores are produced in basidia as basidiocarps. Ascospores are produced in asci as ascocarps.
 |
| A typical Fungi |
A) Asexual Reproduction:
It takes place by the following methods.1. Spores:
Sporangia are structures produced at the tip of erect hyphae and cut off from the hyphae by complete septa, where spores are produced inside the sporangium.Spores are haploid, non-motile and are produced in very large number. Water is not needed for the dispersal of spores.
Spores are dispersed by wind. Thus, spores are widely distributed. Spores may be dispersed by insects and small animals under favorable conditions. Spores germinate and give rise to new fungal hyphae.
2. Conidia:
These are non-motile, asexual spores, and present at the tip of modified hyphae called conidiophores.
Conidia are not inside the sporangia and usually form a chain or cluster. Conidia are produced in large number and can survive for weeks.
3. Fragmentation:
When mycelium breaks into pieces it is called fragmentation. Each fragment of the hyphal fungi gives rise to a new mycelium.4. Budding:
A bud is a tiny outgrowth which may separate and grow. e.g. Yeasts.
B) Sexual Reproduction:
Sexual reproduction vary in different groups of fungi. Fusion of haploid nuclei and meiosis are common to all.During sexual reproduction hyphae of two genetically different but compatible mating types come together, their cytoplasm fuse followed by nuclear division.
In Basidiomycetes and Ascomycetes, fusion of nuclei i.e; karyogamy does not take place immediately after the fusion of cytoplasm i.e; plasmogamy: The two genetic types of haploid nuclei from two individuals may coexist and divide in the same hyphae for most of the life of the fungus and such a hyphae that contain paired haploid nuclei is said to be n+n or dikaryotic or heterokaryotic.
When the nuclei fuse the zygote undergoes meiosis prior to formatin of spore. Fungus spores germinate directly into haploid hyphae.
Different fungi group produce different types of haploid sexual spores. Basidiospores are produced in basidia as basidiocarps. Ascospores are produced in asci as ascocarps.
0 comments:
Post a Comment