MYCOLOGY Mycology is the branch of biology concerned

MYCOLOGY Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy a nd their use to humans as a sourcefor tinder, medicine, f ood, and entheogens, as well as their dangers, such as toxicity or infection.

General characters of fungi Fungi are the eukaryotic, achlorophyllous, and unicellular or multicellular organisms, which may reproduce by asexual and sexual spores. 1. All are eukaryotic - Possess membrane-bound nuclei (containing chromosomes) and a range of membrane-bound cytoplasmic organelles (e. g. mitochondria, vacuoles, endoplasmic reticulum). 2. Most are filamentous - Composed of individual microscopic filaments called hyphae, which exhibit apical growth and which branch to form a network of hyphae called a mycelium. 3. 3. Some are unicellular - e. g. yeasts.

4. Protoplasm of a hypha or cell is surrounded by a rigid wall - Composed primarily of chitin and glucans, although the walls of some species contain cellulose. 5. Many reproduce both sexually and asexually - Both sexual and asexual reproduction often result in the production of spores. 6. Their nuclei are typically haploid and hyphal compartments are often multinucleate Although the oomycota and some yeast possess diploid nuclei.

7. All are achlorophyllous - They lack chlorophyll pigments and are incapable of photosynthesis. 8. All are chemoheterotrophic (chemoorganotrophic) - They utilise pre-existing organic sources of carbon in their environment and the energy from chemical reactions to synthesize the organic compounds they require for growth and energy. 9. Possess characteristic range of storage compounds - e. g. trehalose, glycogen, sugar alcohols and lipids. 10. May be free-living or may form intimate relationships with other organisms i. e. may be freeliving, parasitic or mutualistic (symbiotic).

Thallus The body of the fungus is called as 'thallus'. Eucarpic thallus The thallus is differentiated into vegetative part, which absorbs nutrients, and a reproductive part, which forms reproductive structure. Such thalli are called as eucarpic. e. g. Pythiumaphanidermatum.

Holocarpic thallus The thallus does not show any differentiation on vegetative and reproductive structure. After a phase of vegetative growth, it gets converted into one or more reproductive structures. Such thalli are called as 'holocarpic' e. g. yeast, Synchytrium endobioticum

Structure of Kingdom Fungi

1. Almost all the fungi have a filamentous structure except yeast the cells. 2. They can be either single-celled or multicellular organism. Fungi consist of long thread-like structures known as hyphae. 3. These hyphae together form a mesh-like structure called mycelium. 4. Fungi possess a cell wall which is made up of chitin and polysaccharides.

Modes of nutrition On the basis of nutrition, fungi can be classified into 4 groups. Saprophytic – The fungi obtain their nutrition by feeding on the dead organic substances. Examples: Rhizopus, Penicillium, and Aspergillus.

Parasitic The fungi obtain their nutrition by living on other living organisms (Plants or animals) and absorb nutrients from their host. Examples: Taphrina, and Puccinia.

Symbiotic These fungi live by having an interdependent relationship association with other species in which both are mutually benefited. Examples: Lichens and mycorrhiza. Lichens are the symbiotic association between algae and fungi. Here both algae and fungi are mutually benefited as fungi provides shelter for algae and in reverse algae synthesis carbohydrates for fungi

Reproduction in Fungi

Reproduction in fungi is both by sexual and asexual means. The sexual mode of reproduction is referred to as teleomorph and the asexual mode of reproduction is referred to as anamorph.

Vegetative reproduction By budding, fission, and fragmentation Asexual reproduction This takes place with the help of spores called conidia or zoospores or sporangiospores

Sexual reproduction ascospores, basidiospores, and oospores The conventional mode of sexual reproduction is not always observed in the kingdom Fungi. In some fungi, the fusion of two haploid hyphae does not result in the formation of a diploid cell. In such cases, there appears an intermediate stage called as the dikaryophase. This stage is followed by the formation of diploid cells.

Classification of Fungi The classification is based on the spore case. Phycomycetes These are obligate parasites found in moist and damp places or decaying woods. Example – Rhizopus

Ascomycetes They are also called as sac fungi. They can be coprophilous, decomposers, parasitic or saprophytic. Example –Aspergillus

Basidiomycetes Mushrooms are the most commonly found basidiomycetes and mostly live as parasites. Example- Agaricus

Deuteromycetes They are otherwise called imperfect fungi as they do not follow the regular reproduction cycle as the other fungi. Example – Trichoderma.

Bryophyte Definition Bryophytes are a group of plant species that reproduce via spores rather than flowers or seeds. Most bryophytes are found in damp environments and consist of three types of non-vascular land plants: the mosses, hornworts, and liverworts.

The following characteristics are exhibited by bryophytes: Bryophytes are non-vascular land plants. Although they do exhibit specialized structures for water transportation, they are devoid of vascular tissue. Bryophytes grow primarily in damp environments but can be found growing in diverse habitats ranging from deserts, the artic, and high elevations. Since bryophytes do not depend on root structures for nutrient uptake like vascular plants, they are able to survive in environments that vascular plants cannot (e. g. , on the surface of rocks).

All bryophytes have a dominant gametophyte stage in their life cycle. During this stage, the plant is haploid and the sex organs that produce the gametes are developed. Bryophytes are unique compared to many other plant species in that they remain in this stage for long periods. The sporophytes (the diploid form of the plant) of bryophytes are unbranched, producing a single spore-producing capsule (sporangium). Moreover, the sporophytes are dependent on the gametophyte for nutrition and develops within the female sex organ (archegonia).

Bryophyte Life Cycle The bryophyte lifecycle consists of alternating generations between the haploid gametophyte and the diploid sporophyte. During the gametophyte stage, haploid gametes (male and female) are formed in the specialized sex organs: the antheridia (male) and archegonia (female).

Bryophyte Examples The three main types of bryophytes consist of the liverworts, mosses, and hornworts, each of which encompasses several hundred different species. Liverworts (shown below) are extremely small plants characterized by flattened stems and undifferentiated leaves, as well as single-celled rhizoids. Liverworts can be distinguished from other bryophyte species by the presence of membrane-bound oil bodies within their cells, compared to other species which do not contain enclosed lipid bodies.

Mosses (shown below) are green, clumpy plants often found in moist environments out of direct sunlight. Mosses are characterized by leaves that are only one cell wide attached to a stem that is used for water and nutrient transportation. Mosses are able to absorb a substantial amount of water and have historically been used for insulation, water absorption, and a source of peat.

Hornworts (shown below) are named after the characteristic long horn-like sporophyte that develops. In contrast, the gametophyte form is a flat, green-bodied plant. Most hornworts are found in damp environments (e. g. , tropical climates), garden soils, or tree bark.