The most common method of vegetative reproduction is fragmentation.
Asexual and sexual reproductive spores of fungi hypha breaks up into small fragments accidentally or otherwise. Each fragment develops into a new individual. In addition to above-mentioned common method of vegetative reproduction the fungi reproduced vegetatively by means, such as fission, budding, sclerotia, rhizomorphs, etc.
In fission, the cell constricts in the centre and divides into two giving rise to new individuals. The budding is commonly found in Saccharomyces.
The buds arise from the protoplasm of the parent cells and ultimately become new individuals. The sclerotia are resistant and perennating bodies. They survive for many years. Each sclerotium is cushion-like structure of compact mycelium.
They give rise Asexual and sexual reproductive spores of fungi new mycelia on the approach of favourable conditions. As mentioned under the modified mycelium, the rope-like rhizomorphs are also resistant to unfavourable conditions and give rise to new mycelia even
Asexual and sexual reproductive spores of fungi several years on the approach of favourable conditions.
The asexual reproduction takes place by means of spores. Each spore may develop into a new individual. The spores may be asexually or sexually and thus named a asexual spores and b sexual spores.
Under asexual reproduction, only asexual spores will be considered. They are innumerable and produced on the diplont mycelium in Phycomycetes and Ascomycetes.
In Basidio- mycetes they are produced on the diplont mycelium. The spores are Asexual and sexual reproductive spores of fungi diverse type and borne upon special structures called the sporophores.
These spores are produced asexually and called the asexual spores. Usually the spores are uninucleate and nonmotile but multinucleate and motile spores are also Asexual and sexual reproductive spores of fungi. The fungus producing more than one type of spores is called the pleomorphic or polymorphic.
The spores produced inside the sporangia are termed the endogenous spores and the spores developing exogenously on the terminal ends of sporophores are called the exogenous spores. The endogenous spores are produced within the Asexual and sexual reproductive spores of fungi spore producing cell the sporangium. The sporangia may be terminal or intercalary in their position.
The sporophores which bear the sporangia on their apices are called the sporangiophores. They may be branched or unbranched. The spores produced inside the sporangia are called the endospores or endogenous spores produced inside the sporangia are called the endospores or endogenous spores. They may be motile or non-motile. The motile spores are called the zoospores and the non-motile aplanospores.
The zoospores are produced inside the zoosporangia. The protoplasm of the sporangium divides into uninucleate or multinucleate protoplasmic bits and each bit metamorphoses into a spore. The endogenously produced zoospores are uni or
Asexual and sexual reproductive spores of fungi. Each spore is without any cell wall, uninucleate and vacuolate. They can move with the help of their flagella. They are usually kidney-shaped or reniform and the flagella are inserted posteriorly or laterally on them.
Asexual and sexual reproductive spores of fungi been recorded from Albugo, Pythium, Phytophthora and many other lower fungi.
The aplanospores are non-motile, without flagella and formed inside the sporangia. They may be uni or multinucleate e.
These spores lack vacuoles and possess two layered cell walls.
The outer thick layer Asexual and sexual reproductive spores of fungi epispore or exospore which may be ornamented in many cases. The inner thin layer is endospore. The spores producing externally or exogenously are either called the exogenous
Asexual and sexual reproductive spores of fungi or conidia.
They are produced externally on the branched or unbranched conidiophores. The condiophores may be septate or aseptate. The conidia borne upon the terminal apices of the conidiophores or the ends of the branches of the condiophores.
The conidia may be produced singly on each sterigma or in chains. The conidial chains may be basipetal to acropetal in succession.
The conidia are diverse in their shape and size. They may be unicellular or multicellular, uninucleate or multinucleate.
Different genera may be recognized only by the presence of various shaped and various coloured conidia. In other type of exospores, the sporophores develop in groups and form the specialized structure called the pustules, pycnia, aecidia, acervuli, and sporodochia. The pycnia are flask-shaped producing pycniospores in them. The acervuli are saucer- shaped widely open bodies having developed conidia in them on small conidiophores.
In mushrooms the sporophores are compactly arranged and form an umbrella-like fructification. The terminal expanded portion bears gills. In each gill there are hundreds of sporophores called the basidia bearing basidiospores.
The sporophores basidia are Asexual and sexual reproductive spores of fungi in hymenia.
A large number of fungi reproduce sexually. Usually two phases are found in the life cycle of the plants. These phases are called haploid and diploid phases respectively. The haploid phase possesses the n number of chromosomes in the nucleus, whereas this number becomes 2n in the diploid phase. The gametes are always haploid n and by a sexual fusion they result in diploid 2n sexual spores, such as zygospores, oospores, etc. To bring haploid n phase once again Asexual and sexual reproductive spores of fungi the life cycle the reduction division meiosis takes place and the number of chromosomes becomes half.
The gametes taking part in sexual fusion may be morphologically or physiologically different. Such two gametes taking part in fusion are of opposite Asexual and sexual reproductive spores of fungi or strains, which may be called male and female sex organs or plus and minus strains.
When both the sex organs or strains occur on same mycelicum, the fungus is said to be monoecious or homothallic, and when the Asexual and sexual reproductive spores of fungi and female sex organs or plus and minus strains occur separately on different mycelia the fungus is said to be dioecious or heterothallic.
The gametes taking part in fusion are usually formed in the cells of sacs called gametangia singular-gametangium. The morphologically identical male and female gametes are called the isogametes. The morphologically dissimilar male and female gametes are called the heterogametes. In such cases the male gametes are called the antherozoids and the ones are the eggs.
The fusion of the plasma of the gametes is called the plasmogamy, which is usually followed by the nuclear fusion, i. The whole process is called the fertilization.
Sometimes, in some of the fungi, e. In the members of Phycomycetes and Ascomycetes the gametangia taking part in gametangial copulation are called the antheridia singular-antheridium and the oogonia singular-oogonium. In the lower fungi, there is complete fusion of the nuclei of Asexual and sexual reproductive spores of fungi two different strained gametes in the sexual union, i. In the opposite cases where the mycelium possesses single haploid nucleus of either strain in each cell is called the monocaryotic mycelium.
The most common methods of sexual reproduction are as follows:. This type of sexual reproduction involves the fusion of two naked gametes one or both of them are motile. The motile gametes are known as planogametes. The most primitive fungi produce insogamous planogametes, e.
The anisogamous planogametes are only found in the genus Allomyces of order Blastocladiales. In Monoblepharis order Monoblepharidales the unique condition is present here the female gamete is non-motile whereas the male gamete is motile. The male gamete enters the oogonium and fertilizes the egg. This method of reproduction is found in many lower fungi class Phycomycetes.
In this method two gametangia of opposite sex oogonium and antheridium come in contact and one or more gamete nuclei migrate from the male gametangium antheridium to the female gametangium oogonium.
In no case the gametangia actually fuse. The male nuclei in some species enter the female gametangium through a pore developed by the dissolution of the wall of contact e. After the migration of the nuclei the antheridium eventually disintegrates Asexual and sexual reproductive spores of fungi and sexual reproductive spores of fungi the oogonium continues its development in various ways. In this method of sexual reproduction the fusion of the entire contents of two contacting compatible gametangia takes place e.
The sexual reproduction in Neurospora Class- Ascomycetes and other fungi takes place by means of this method. The minute, uninucleate, spore-like male structures are known as spermatia. They are produced in several ways. The spermatia are carried by outer agencies to the receptive hyphae trichogynes of female gametangia, to which they become attached. A pore develops at the wall of contact
Asexual and sexual reproductive spores of fungi the contents of spermatium pass into the female gametangium through the receptive hypha.
The sex organs are not produced. The somatic cells take part in sexual fusion, e. You must be logged in to post a comment. Asexual Reproduction in Organisms: