In this article we will discuss about the brief history of mycology.
Beautifully coloured umbrella shaped mushrooms and toad stools growing on soils forming ‘fairy rings’ attracted Man from the very beginning. One finds references to fungi in Roman and Greek classics. Records of plant diseases could also be found in Vedas and the Bible.
Herbals or books containing descriptions of fungi were published by several authors like Clusius (1601) J. F. van Steerbeck (1675), Robert Hooke & others. The most famous work of their period was published by P. A. Micheli (1679- 1737) who included scientific descriptions and illustrations of many fungi know till then.
His famous book Nova plantarum genus was published in 1729. He experimentally proved that fungi originated from spores thus putting an end to the theory of fungal origin from decaying materials. He was much ahead of his time and thus has the honour of being referred to as Father of Mycology.
The number of species and genera discovered and described increased rapidly due to the diligently pursued researches by several renowned mycologists of that period. They included Persoon (1801), Fries (1821-32), DeBary (1831-1888), Saccardo (1845-1920), Sydow (1851- 1924) and others.
Soon it was proved beyond doubt that fungi caused diseases in plants, mycologists became interested in studying diseases of plants, animals and human beings. Cereal rusts, smuts warts etc. were observed and described by French, Italian, English and Russian mycologists.
The fact that yeasts were associated with fermentation announced independently by C. C. de la Tour (1836), T. Schwann (1837) and F.T. Kutzing (1837) opened new vistas in commercial exploitation of Fungi. Similarly, the discovery of penicillin by Alexander Fleming in 1928 initiated new avenues for therapeutic value of Fungi. Since then, a large number of fungi have been discovered to produce antibiotics.
Dangeard (1894) and Harper (1896-97) initiated Cytological Studies on Fungi while Dodge and Shear (1898) using Neurospora for genetical studies contributed to the laws of heredity, genetical control of enzyme and evolution of new improved varieties. Sexual reaction studies in Fungi were initiated by Blakeslee (1904) who discovered heterothallism in Fungi.
Mycological studies in India were initiated by Lt. Col. K.R. Kirtikar in late 19th Century who collected and identified fungi. In a real sense, studies on mycology and plant pathology in India began with the establishment of the then Imperial Agricultural Research Institute at Pusa (Bihar) and the arrival of Sir E.J. Butler as the first imperial Mycologists to the then Govt, of India in 1905.
It was mainly due to painstaking efforts of Butler that a firm foundation of mycology and Plant pathology was laid in this country. He authored a classic book “Fungi and Diseases in Plants” which is still used both by students and researchers. Because of his contributions Butler is aptly referred to as the Father of Indian Mycology.
Studies on isolation, collection and identification of both macro and micro fungi including parasitic fungi continued with more enthusiasm and several mycologists contributed in describing new fungi unknown to India. P. Bruhl and J. SenGupta (1927) compiled a checklist of Myxomycetes while H. Chaudhari (1947) and his coworkers compiled their work in the form of “Handbook of Indian water moulds”.
Additions to the aquatic fungi were also made by S. N. Das Gupta and R. John (1953).
Parasitic fungi causing diseases of important crops received greater attention. B.N. Uppal and J.H. Weston (1936) made comprehensive studies of Sclerospora the cause of Green ear disease of Bajra.
Species of Pythium and Phytophthora causing diseases of rubber plants and palms received attention from S.L. Ajrekar and K.D. Rajulu (1931). In 1931 itself, M. Mitra recorded a new bunt or Kamal Bunt of wheat while a list of Indian Species and varieties of Aspergillus was published by U.N. Mohanty (1948).
B.B. Mundkur and M.J. Thirumalachar in 1952 published a consolidated list of Indian Ustilaginales. Earlier in 1947, Mundkur founded the Indian Phytopathological Society with S.R. Bose as its first president. K.C. Mehta and Coworkers (1940) studied the problem of the recurrence of the wheat rusts in plains of India.
Indian Mycological researches got an impetus with the establishment of the universities of Bombay, Madras and Calcutta. The then mycologists were purely plant pathologists who gave more importance to the listing and description of parasitic fungi causing diseases in plants.
In addition to mentioned above, the prominent names include K.D. Bagchee, T.S. Ramakrishnan, J.H. Mitter, K.J. Narsimhan, S.N. Das Gupta, R.N. Tandon, R. Prasad, T.S. Sadasivan, C.V. Subramaniam and others.
The mycologists who studied slime molds and soil fungi were B.S. Mehrotra (1952-1970) on Mucorales; B. Bakshi (1954) on Fungi from Himalayas, V. Agniothrudu (1954-68) slime molds and soil fungi from North and North East India; K. S. Bhargava (1968-80) on taxonomy of soil fungi; J. N. Rai (1961-83) on taxonomy of soil fungi from usar soils and Mangroves.
Ecological, physiological and Biochemical studies on fungi were also undertaken at different centres in the country. T. S. Sadasivan at Madras University initiated studies on ecology and physiology of Soil Fungi; S.N. Das Gupta at Lucknow University established a centre of studies on histopathology and deficiency disorders, A. Mahadevan at Madras University made significant contributions on physiology and biochemistry of fungi; at the University of Allahabad, R.K. Saksena initiated detailed studies on storage diseases of fruits and vegetables which were ably continued by R.N. Tandon. K.S. Bilgrami at Bhagalpur contributed on physiology and biochemistry of fungi especially the aflatoxins.
Studies on phyllosphere fungi were initiated by S. Sinha at Agra. J.N. Rai at Lucknow conducted Ecological studies on soil fungi especially those from usar soils. Other prominent mycologists who are engaged in studies on taxonomy, ecology and biochemistry of fungi include R.S. Dwivedi, B. Rai, K.G. Mukergi, RD. Sharma, H.C. Dube, S. Chandra, Kamal & A K Sinha.
Butler and Bisby (1931) published the first systematic account of Indian Fungi. Later several supplements were brought out by Mundkur (1938), Ramkrishnan and Subramanian (1952), Vasudeva (1977), and Bilgrami, Jamaluddin and Rizvi (1979).
Origin and phylogeny of Fungi:
The origin and evolutionary relationships of fungi are not definitely known. They are a matter of speculation and problem for future research for mycologists. Concerning their origin, the first and the traditional hypothesis regards algae as the ancestral stock. Some mycologists consider protozoa as the ancestral stock.
The supporters of the algal hypothesis hold that the fungi are degenerate algae which have lost their chlorophyll and thus have adapted themselves of a heterotrophic mode of nutrition. It is not difficult to believe it because certain flagellates under different conditions develop chlorophyll and prepare their own food or lose chlorophyll and live as saprobes.
The proponents of algal hypothesis are divided into two camps. Some suggest a monophyletic origin. They hold that with the exception of slime molds and some simplest fungi, all others, namely, Phycomycetes, Ascomycetes and Basidiomycetes represent one main evolutionary line of fungi evolved from an algal ancestor.
To view that all fungi have a common ancestry and arose in a monophyletic series appears untenable to most of the mycologists. They support the polyphyletic origin from the various groups of algae.
On the basis of multiple origins, the fungi are considered a heterogeneous aggregation, the Phycomycetes having evolved from one class of algae and Ascomycetes from another. The basidiomycetes are thought to have been evolved from the Ascomycetes.
The supporters of the algal origin of the Phycomycetes further belong to two opposite schools of thought. One favours algal origin from a siphonaceous ancestor belonging to the green algae and the other from a Xanthophycean ancestor such as Vaucheria. There are differences in metabolism and type of flagellation of the motile cells in the Phycomycetes and green algae (Table II).
In view of the above-mentioned differences in metabolism and type of flagellation in the two groups, the opponents of the chlorophycean origin of Phycomycetes consider this hypothesis untenable.
The advocates of the Xanthophycean origin of the Phycomycetes base their hypothesis on the resemblances of structure and reproduction between the Oogamous Phycomycetes (Oomycetes) and Oogamous yellow-green algae (Xanthophyceae) such as Vaucheria.
In both the somatic phase is a coenocytic, aseptate filamentous thallus. They have more or less an identical life cycle and oogamous sexual reproduction. There is similarity in the chemical composition of cell wall in both. This viewpoint of phycomycetean origin of fungi from Vaucheria-like ancestors was propounded by De Bary in 1881.
The name Phycomycetes of algal fungi emphasises this viewpoint. De Bary envisaged the origin of Saprolegnia-like oomycete from a vaucherial ancestor by loss of chlorophyll and change in the mode of nutrition. It further gave rise to the chytrids and to the Zygomycetes by retrogression.
Some mycologists led by Bessey (1942) advocated algal origin of fungi from the unicellular coccoid Xanthophyceae. This hypothesis is based on the similarity in structure, anterior position of flagella, and presence of cellulose in the cell wall and accumulation of reserve food in the form of glycogen in both the Phycomycetes and the coccoid ancestor.
The coccoid ancestor gave rise to the Phycomycetes along two divergent lines, one with anteriorly uniflagellate swarmers and the other with biflagellate swarmers. The opponents of this hypothesis point out to the occurrence of posteriorly uniflagellate swarmers and absence of cellulose in the cells of some uniflagellate Phycomycetes.
They argue that all the uniflagellate and biflagellate Phycomycetes have not evolved from a common ancestor. They are polyphyletic in their origin, some having evolved from an algal ancestor and the others from a protozoan (flagellate) ancestor.
Fischer and Dangeard advocate the protozoan (flagellate) ancestry of the Phycomycetes. To the modem mycologists, this hypothesis seems more probable. It is based on similar metabolism and type of flagellation in both the Phycomycetes and protozoans.
On the basis of this theory, the Phycomycetes have evolved from the flagellates via the chytrids. The uniflagellate forms arose from the uniflagellate protozoa and biflagellate forms evolved from the biflagellate protozoa. These non-mycelial forms, in turn, gave rise to the more advanced mycelial forms by progressive evolution.
Hawker (1967) suggests a polyphyletic origin of the lower fungi (Phycomycetes) from the aquatic flagellates along parallel lines. According to him, Chytridiales, Hyphochytridiomycetes and Plasmodiophoromycetes have originated from flagellates having appropriate types of flagella.
The Oomycetes which resemble certain filamentous algae in the composition (cellulose nature) of cell wall, form of sex organs, life cycle, and form of endoplasm and mitochondria may have evolved from an algal ancestor by the loss of chlorophyll.
Hawker suggests common ancestry for the chytrids and Zygomycetes at the flagellate level. The floridian origin of higher fungi based on the similarities between the reproductive organs does not survive critical examination.
To hold that different classes of fungi have an independent (polyphyletic) origin means there is no relationship between them. In that case, the classes of fungi should be raised to the status of divisions of phyla.
This view suffers from a drawback as how to explain the close similarities which exist between the different classes of fungi such as:
1. Similarity between the antheridia and oogonia of Phycomycetes and the sex organs of Ascomycetes.
2. Similar origin, physiology and phylogeny of the ascus and the basidium.
3. Similar nature, origin and development of conidia.
4. Similarity of the somatic phase (mycelium) differing, of course, in the magnitude of specialisation and differentiation.
The above-mentioned similarities indicate that the higher fungi have a common origin. The tendency among the Zygomycetes towards evolution of the conidium and protection of the zygote indicate an affinity with the Ascomycetes. Gaumann thus advocates that the Ascomycetes have evolved from the Zygomycetes.
Similar origin, physiology and phylogeny of the ascus and the basidium support the origin of the Basidiomycetes from the Ascomycetes. Saivle (1955) postulated a highly plausible theory of the origin of the Ascomycetes and Basidiomycetes from a Taphrinalike ancestor.
Burnett (1968) disapproves speculation of the phylogenetic trends based on the similarities between the reproductive parts and on the study of comparative morphology. According to him speculation based on “this type of study can hardly be proved. Its plausibility cannot be subjected to scientific testing”.