Breif Description About Fungi

Brief Description About Fungi

The fungi constitute the largest and diverse group of the plant kingdom. Some of the earlier mycologists included the bacteria with them, but that is rarely done nowadays. The majority of botanists, or to be more specific, of mycologists, include the Slime Molds among the fungi.

From the foregoing it is apparent that the fungi do  not possess chlorophyll and also that the chlorophyll fewer bacteria and Mycetozoa is excluded from its ranks. There are many other organisms that lack chlorophyll and still are not fungi. Thus in the diatomaceous genus Nitzschia, some species are known that possess no chloroplasts while the majority of species possess them. Otherwise, they are so similar that they are so similar that they are retained in the same genus. In the Red Seaweesa, there are several species that lack chlorophyll and are parasitic upon others are several species that lack chlorophyll and are parasitic upon other Florideae-e.g., Harveyella mirabilis Schmitz and Reinke. Yet in their modes of sexual and sexual reproduction, they can be assigned definite positions among these algae. Among the higher plants, many widely separated chlorophyll fewer species are found, e.g. in the Orchidaceae and Burmanniaceae among the Monocotyledoneae, and Cuscuta, Cassytha, Monotropa, Rafflesia, Orobanche, and many other dicotyledonous.

Fungi definition biology

As a group the fungi may be defined is in the main negative  nonvascular plants whose reproductive or vegetative structures do not permit them to be assigned to positions among recognized groups of algae or higher plants, and as excluding the Bacteria and Mycetozoa and animal type of structure and reproduction.

 

History of Fungi

In ancient times the Roman people knew about some edible and poisonous mushrooms. In those times the Greek word ‘mykes’ was used for some fungi. Still today the word Mycology stands for the science of fungi. At the beginning of the seventeenth century, in Europe.

Much more work has been done on the systematic mycology by various mycologists all over the world. The life histories of the various species have been studied from different classes of the fungi. The extensive programs of the importance of fungi to human beings have been taken in the hands and several kinds of research have been done for the welfare of humanity by various fungi.

In India serious studies in fungi including plant diseases by some of them started with the establishment of Imperial Agricultural Institute at Pusa, Bihar (now known as Indian Agricultural Research Institute, New Delhi) in the first decade of this century. E.J.Butler, the  first Imperial mycologist of Pusa Institute is regarded as the father of Indian mycologist and Plant Pathology.

Structure of fungi

The vast majority of fungi consist vegetatively of more or less elongated, septate of nonspetate filaments. These are called individually hyphae and collectively the mycelium. They may be uniform in thickness or tapering from broad to slender portions in the same hypha or in different portions of the same mycelium. They may be branched or unbranched. In thickness, they may be less than 0.5micron to 100micron in length.

The composition of the cell wall is very variable among the different fungi and sometimes in the same individual at different stages of maturity. Basically, the chief components appear to be various types of carbohydrates or mixtures of these: cellulose, pectose, callose, etc. Mixed with these and probably often in chemical combination with them, there may be other substances.

There are two main types of mycelium; in one the hyphae are cellular and in the other, coenocytic. Cellular hyphae usually contain either one or two nuclei per cell and the division of the cell is initiated by the division of the nucleus or by the simultaneous division of both nuclei, respectively. In a coenocyte, there are many nuclei and the formation of septa occurs without immediate reference to any preceding nuclear division. A coenocytic hypha may be “tubular”,:i.e., lacking septa, or septate.

REPRODUCTION IN FUNGI

The fungi reproduced many ways such as Asexual, sexual and vegetative mode of reproduction.

Vegetative reproduction

The most common mode of vegetative reproduction is fragmentation. The hypha breaks up into the small fragments accidentally and each fragment gives rise or developed into a new individual. In the laboratory, the hyphal tip method is commonly used for the development of fungi.

In addition to fragmentation, fungi can also reproduce vegetatively by the following method also

• Fission
• Budding
• Sclerotia
• Rhizomorphs etc.

 

Asexual reproduction

In asexual mode of reproduction formation of spore is taking place and each spore is give arise to new individuals. the spore may be asexual as well as sexual , spore which produce by the asexual method is known as an asexual spore

Asexual spore

They are innumerable and produced on the plant mycelium in Phycomycetes and Ascomycetes. In Basidiomycetes  they produce on the diplont mycelium.

sexual reproduction

A large number of fungi reproduce sexually. However, the members of ‘Fungi Imperfecti “or “ Deutromycetes” does not reproduce by sexual reproduction

The most common method of sexual reproduction is as follows

• Planogametic copulation
• Gametangial contact
• Gamentangial  copulation
• Specialization
• Somatogamy