Fungus

General characteristics of Fungi Importance of fungi: Some fungi are harmful and some are beneficial to us. Harmful effect of fungi: Cause disease in plant: Fungi are the major groups of pathogens causing many severe diseases in plants. e.g. Blast disease of rice- Pyriculaia oryzae, Late blight of potato- Phytophthora infestans. Spoil food: Fungi destroy stored food stuffs, vegetables and fruits. Aspergillus and Penicillium spoil stored food. Spoil valuable things: Fungus grow on decompose cloths, leather, furniture and buildings. e.g. Rhizopus grow on cloths and taint. Serpula lachrymans decompose woods, thus affect furniture and equipments. Cause human disease: Spores produced by fungi may cause asthma and respiratory problems.

Beneficial activities of fungi: Importance of Fungi Beneficial activities of fungi: Food: Traditionally, mushrooms were identified and picked for food. Mushrooms are now commercially cultivated. Agaricus campestris is used as delicious food in the hotel. Decomposer: The ability of fungi to decompose major plant components - particularly lignin and cellulose - is the basis of their organic recycling role. Without decomposer fungi, we would soon be buried in litter and debris. e.g Auricularia auriculajudae. Increase soil fertility: Fungi decompose leaf litter, twigs, branches and logs into organic matter and recycle nutrients to the soil. Mycorrhiza fungi act as an extension of the root system, resulting in improved nutrient uptake for the plant. 3

Biocontrol agents: Penicillium, Trichoderma, Phoma etc Biocontrol agents: Penicillium, Trichoderma, Phoma etc. control plant diseases. 5. Industrial use: yeast use in bread preparation, Aspergillus flavous produces digestion enzyme, Penicillium produces antibiotic

Fungi are chlorophyll-less Fungi are nucleated organisms. Morphology: Fungi are chlorophyll-less Fungi are nucleated organisms. The vegetative body of the fungi is called mycelium. Mycelium is the mass of hyphae. Hyphae are the filamentous structures. Fungi are unicellular or multicellular organisms. The cross-walls which divide the hypha into cells are called septa. Hyphae of some fungi do not have septa are called aseptate or coenocytic. Thickness of hyphae is usually 2 to 10 micrometers, but in some it is more than 100 micrometers. The length of the mycelium may be only a few micrometers, but in some fungi it may be several meters long. Zoospores is the only fungal structures that can move by themselves. One small fungal thread is a hypha. Many hyphae bundled together make mycelium

Modification of mycelium Hyphae are modified in different ways: STROMA It is a compact, somatic structure which looks like a mattress. On the stroma fructifications (structures containing, spores) are formed. eg. Taphrina maculans SCLEROTIUM It is a mass of hyphae usually with a darkened skin. It is a resting structure and resistant to unfavorable conditions. eg. Sclerotium rolfsii RHIZOID Some fungi produce root-like structure from mycelium is called rhizoid. Rhizoid are used to attach with substrate. eg. Rhizopus sp. Rhizoid

HAUSTORIUM: A simple projection of hyphae into host cells that acts as an absorbing organ. eg. Hyaloperonospora brassicae. Haustorium

Fungi reproduce both 1. Asexually and 2. Sexually Reproduction: Fungi reproduce both 1. Asexually and 2. Sexually The asexual state is referred to as anamorph and the sexual state is termed as teleomorph. Many fungi can have both. Asexual reproduction: Reproduction without nuclear fusion. Asexual reproduction occurs under favorable condition and is repeated several times in the life cycle. Fig. Hyphae of Penicillium

Different types of asexual reproduction are found in fungi: Fragmentation of hyphae: Oidiospore/Arthrospore Chlamydospore Fission Budding Production of asexual spores Production of Sporangiospore Zoopsore Aplanospore Production of Condia Loose Asexual Fruiting body Pycnidium Acervulus Sporodochium Synnema

Fragmentation of hyphae: Oidia/arthrospore: The hyphae break up into their component cell, which behave like spores. They are called oidia or arthrospore. e.g. Erysiphe Chlamydospore: When the cells become enveloped in a thick wall before they separate from other hyphal cells, are called chlamydospores. e.g. Fusarium

Fission: The cell is split into two daughter cells by constriction and formation of a cell wall. This method is called fission which is commonly found in yeasts. Budding: Small outgrowth (bud) is produced from a parent cell. The nucleus of the parent cell divides and one daughter nucleus migrates into the bud. The bud increases in size, ultimately breaks off and forms a new individual.

Production of asxual spores: Fungi produce two types of asexual spores- sporangiospore and conidia Sporangium: Sporangium is a sac-like structure and its entire contents are converted into one or more spores which are called sporangiospores., e.g. Rhizopus Zoospores: If the sporangiospores are motile (swim), have one or two flagella. Two types of flagella are found, one is whiplash and another is tinsel flagellum. Sporangiospores Aplanospores: If the sporangiospores are non-motile and have no flagella.

Conidia: Conidia are produced at the tips or sides of hyphae. The specialized hypha which bears conidia is called condiophore. Conidiophore production by hyphae can be grouped in --------- loose and indiscriminate: Conidia and condiophores are formed at tip of the hyphae asexual fruiting bodies/conidiomata: Conidia and condiophores are produced inside walled structure is called Asexual fruiting bodies. The various fruiting bodies are- Pycnidium Acervullus Sporodocium Synnema

Pycnidium: it is flask shaped structure whose inner walls are lined with condiophores. eg. Septoria sp. Acervulus: When closely packed short condiophores arise from hyphal mat and form a bed-like-mass is called acervulus. eg. Colletotrichum sp. Septoria leaf spot of tomato Pycnidium of Septoria sp.

iii. Sporodochium: When conidiophores arise from the surface of cushion-shaped stroma is called sporodochium. eg. Fusarium sp. iv. Synnema: Synnema is a group of conidiophores cemented together to form an elongated feather-like structure. eg. Ceratocystis sp.