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Fresh vegetables are essential part of a healthy diet as it is an important source of vitamins, minerals and fibers. The nutritional content of vegetables varies considerably, though generally they contain little protein, fat and varying proportions of vitamins such as Vitamin A, Vitamin K and Vitamin B6, pro-vitamins, dietary minerals and carbohydrates (Woodruff, 1995; Whitaker, 2001). Vegetables contain multifarious other phytochemicals, some of which have been claimed to have antioxidant, antibacterial, antifungal, antiviral and anti-carcinogenic properties (Steinmetz and Potter, 1996; Gruda, 2005). A balanced diet should contain 250 - 325 g of vegetables and the average human requirement for vegetable is 285 g per person per day (Attavar, 2000). This perception of nutrition makes vegetables as a valued farm output.

To reduce the dependence on hazardous pesticides in modern agriculture, one of the most promising ways is to use insect-resistant cultivars. When available, planting resistant cultivars is one of our most effective, economically viable and environmentally sound tactics. The underlying concept of using host resistance to our advantage comes from the knowledge that most plants and animals are resistant to most potential insect attackers. Certain physiological, morphological, and/or behavioural characteristics inherited by organisms form a core of defense against species that would otherwise attack them (Pedigo, 2002).

Crop improvement

Crop improvement refers to the genetic alteration of plants to satisfy human needs. It deals with the improvement of crops and production of new crop varieties, which are far superior to existing types in all characters. In pre-history, our ancestors in various parts of the world brought into cultivation a few hundred species from the hundreds of thousands available. In the process they transformed elements of these species into crops though genetic alterations that involved conscious and unconscious selection, the differential reproduction of variants. Through a long history of trial and error, a relatively few plant species have become the mainstay of agriculture and thus the world’s food supply. This process of domestication involved the identification of certain useful wild species combined with a process of selection that brought about changes in appearance, quality, and productivity.

Crops plants are broadly classified into two groups based on their mode of reproduction viz. sexually propagated and asexually propagated. In sexually propagated crops seeds are the primary propagules and it is produced by the fertilization of male and female gametes. Whereas, asexual reproduction or clonal reproduction covers all those modes of multiplication of plants where normal gamete formation and fertilization does not take place and vegetative propagules are the means of reproduction. Since sexual reproduction involves meiosis, segregation and recombination, the creation of variation is a continuous process which is inevitable in these crops. On the other hand, in asexual propagation progenies are identical to the parent clones and they are genetically similar without any variation and they reproduce via mitosis. The most important vegetatively propagated food crops are potato, sugar cane, cassava, sweet potato, yam, plantain/banana, and fruit trees. Other crops with asexual propagations are some ornamentals, grasses, and forages.

The primary purpose in plant breeding is to develop better varieties. In order to realize the potential benefit from an improved variety, it should be distributed widely and sufficient seed must be produced so that the variety can be grown on farms in the areas to which it is adopted.  Otherwise much of the breeders work would be wasted.

Variety is a synonym of cultivar and has been defined in the International Code for the Nomenclature for cultivated plants (Anon 1980.) in article 10. ‘’The international term cultivar denotes as assemblage of cultivated plants which is clearly distinguished by any characteristics (morphological, physiological, cytological, chemical or others) and which, When reproduced (sexually or asexually) retains its distinguishing characters”. Indian Seeds Act, under its sub-section 16 of section 2 defined variety as “a sub-division of a kind identifiable by growth, yield, plant, fruit, seed or other characteristic”. Both definitions emphasize that variety should be distinguishable from others and capable of retaining its distinguishable features under multiplication. Therefore production of genetically pure and otherwise good quality pedigree seed is an exacting task requiring high technical skills and comparatively more financial investment. During seed production strict attention must be given to the maintenance of genetic purity and other qualities of seeds in order to exploit the full dividends sought to be obtained by introduction of new superior crop plant varieties.

A. Salinity

Salinity is a predominant problem affecting crop productivity. Over 800 million hectares of land on earth are saline. This accounts for more than 6% of the total land mass on earth. Salinity is a global problem and is prevalent especially in the arid and semiarid regions, where leaching of salts is poor due to low rainfall or irrigation. Brine-affected soil occurs due to natural causes such as weathering and deposition of oceanic salts (eg. recently tsunami in India). In addition, human interference with the environment such as deforestation and/or desertification has resulted in the rising of water table, thus increasing the salt concentration in the root zone. This excess salinity poses a threat to sustainable crop production.

In general, disease means an impairment of health or a condition of abnormal functioning. Plant disease is an abnormal deviation from the normal physiological functioning of the plants their by it causes quantitative and/or qualitative losses. Disease may caused by biotic agents (infectious) like fungi, bacteria, viruses, viroids, phytoplasma, spiroplasma, fastidious bacteria, protozoa, nematodes and parasitic higher plants or abiotic agents (non-infectious) like extreme environmental factors includes temperature, light, soil moisture, atmospheric humidity, environmental pollutants, carbon-dioxide concentration, soil nutrient deficiency, acid rain, soil pH and herbicides. 

Crop varieties are domesticated since civilization, and their continued cultivation depends on continuous breeding programmes for insect, disease and other stress resistance. World wide, insects and their associated problems cause threat to crop production. Many crops suffer from insects, which may be in the form of direct damage by feeding or indirectly by the transmission of diseases by insects as vectors. Until now, chemical crop protection is seen as the major way to combat these problems. However, insects develop resistance to the insecticides very quickly. Apart from controlling pest insects, insecticides also affect beneficial insects, such as predators and parasitoids of the pest insect, pollinators, and harmless fauna, thus upsetting ecological balance results in many unwanted problems. Hence, the best strategy is to prevent the problems that occur. The most economical and environmental friendly way of controlling the insect pests of crops would be through host-plant resistance (HPR). Resistant plants help farmers to grow crops with minimal use of chemicals. This will lead to a reduction in the cost of production, thereby increasing the profit margin for farmers and thus importance of breeding for pest resistance is manifested.

Horticulture, which includes fruits and vegetables, plantation crops, spices, flowers, and medicinal and aromatic plants, has proved beyond doubt its potentiality for gainful diversification. One of the significant developments is that, horticulture has moved from rural confine to commercial production. Recently horticulture has emerged as one of the best option of diversification for effective land use planning and to achieve inclusive growth. The achievement in the development of horticulture through crop improvement is laudable, as the sector now contributes more than 30 percent to GDP of agriculture and has maintained the growth rate of more than 5 percent during the last two decades.

The forest manager aims at producing maximum forest produce of desired quality from the unit forest area in a shortest possible period at a reasonable cost. There is a wide gap between production and requirement from forests. Increasing population and improved standard of living increases demand for forest products. Achieving this in a natural forest is more arduous job. Actual growing stocks in natural stand are poor in terms of vigour, size and quality. The regeneration from these poor stands will produce inferior quality trees. Hence management of forest is inevitable for its improvement.

Plant breeding is considered as current phase of crop evolution. It is a combination of art and science, which involves designers activity, conventionally, economically important traits dispersed in different parental lines are combined together to develop a new variety or cultivar and to change the genetic constitution of a plant to make it more suitable for human need with available scientific knowledge. Although plant breeding has been existing since time immemorial, modern plant breeding methods are based on scientific principles begins only with the rediscovery of Mendel’s laws of inheritance in 1900 and chromosomal theory of inheritance in 1902. Significant achievements have been made in crop improvement through phenotypic selections for agronomically important traits, considerable difficulties are often encountered during this process, primarily due to genotype-environment interactions.

Tissue culture is the culture and maintenance of plant cells or organs in sterile, nutritionally and environmentally supportive conditions (in vitro). Conventional breeding methods are the most widely used for crop improvement. But in certain situations these methods have to be supplemented with plant tissue culture techniques, either to increase their efficiency or to achieve an objective not possible through conventional methods.

As biotechnology increasingly affects almost all aspects of human life, it is essential that the science behind this technology is explained in simple terms to the public to eliminate the misconceptions that may inhibit its acceptability. The basic question that is often asked is what is a gene, a promoter and a terminator? Genes are the basic units of heredity, composed of DNA sequences, which are transmitted from parents to offspring and which, independently or in combination with other genes, control specific traits in an organism. These traits may be, for example, plant height, flower color, fruit and seed size together with regulatory processes, such as assimilate partitioning and drought resistance. Genes are the basis for both the similarity and differences that exist among organisms, and are transmitted from one generation to another.

Plant genetic resource (PGR) is fundamental to crop improvement programme and key to establish future food and nutritional security. In recent times there is a worldwide awakening about the conservation of natural resources viz., land, water and plant genetic resources for the sustainable development of mankind. With the increasing risk from the events like climatic change, natural resource degradation,habitat destruction and environmental pollution etc, now there is an worldwide  debate asking many questions - where the humanity is heading in the this 21st century? Whether the present form of indiscriminate growth pattern is sustainable over a long run?

Bioinformatics is a new science conceptualizing biology in terms of molecules and then applying informatics techniques derived from disciplines such as computer science, maths and statistics to understand and organize the information associated with these molecules on a large scale (Gerstein and Jansen, 2000). It is often defined as the application of computational techniques to understand and organize the information associated with biological macromolecules (Luscombe et al., 2001). It represents a new field at the interface of the twentieth-century revolutions in molecular biology and computers (Pevsner, 2000)

Two decades after India’s independence, during the 1960s, the formal seed sector in India was dominated by the Public sector. It was in 1961 that the National Seeds Corporation (NSC) was established under the Ministry of Agriculture and was at the centre of seed production of breeders, foundation and certified seeds and their quality control. In furtherance of their control in the seeds sector, the National Seeds Project (NSP) was undertaken by the Indian Government in 1967 along with the assistance of the World Bank. In the sixties, the traditional crop breeding and seed production programmes were significantly transformed and modernized with initiation of hybrid development programme in maize, sorghum and pearl millet and introduction, breeding and release of semi dwarf high yielding varieties of wheat and rice.  Indian Seeds Act was enacted in 1966 ensuring official release of varieties and their quality seed production

Significant transformation took place in the traditional variety improvement and seed production programmes in the sixties and modernized with initiation of hybrid development programme in maize, sorghum and pearl millet, as well as with the introduction, breeding and release of semi dwarf high yielding varieties of wheat and rice. To support the release of varieties and their quality seed production Indian Parliament enacted Indian Seeds Act in 1966. Subsequently, National Seeds Corporation was launched by Government of India for scientific growth of seed industry in the country. All these developments led to the green revolution and country attained self-sufficiency in food crops.

Vegetables are defined as edible herbaceous plants or parts of plants consumed as raw or after cooking and are rich in vitamins and minerals, low in calorific value and neutralize the acid substances produced during digestion of high energy foods.  Olericulture is a branch of Horticulture that deals with production, storage, processing and marketing of vegetables and has its origin when man started growing vegetables for consumption. The term Olericulture comes from Latin words holus-holeris = any kind of culinary vegetable, pot herb, and cultura = to cultivate.

Quite a large number of vegetable crops are grown in the country either on a commercial scale or limited to backyards of homesteads.  A few crops have similarity while others have dissimilarity in their climatic and soil requirements, parts used, method of cultivation etc. While describing individual vegetables, there is possibility of repetition in many aspects. In order to avoid repetition, it is essential to classify or group them into different classes/groups. Different methods of classification followed in vegetables are described below: 

Diverse soil and climatic conditions prevailing in different parts of the country offer scope for cultivation of a variety of crops in India.  Around 250 crops either cultivated or grown under natural habitat are used for vegetable purpose.  The crops and varieties vary in their soil and climatic requirements, cultivation practices, resistance to pests and diseases, quality etc.

Considering the climatic conditions for growing vegetable crops and for evolving zone wise technologies and recommendations, the entire country is divided into eight agro-climatic zones under the All India Coordinated  Research Project (Vegetable Crops) as given in Table 1.

Vegetables are grown on a limited scale in homesteads for family use and cultivated in an extensive scale for marketing.  Depending on the purpose for which they are developed, vegetable gardens are classified into different types, viz., kitchen garden or nutrition garden, market garden, truck garden, garden for processing, garden for seed production and vegetable forcing or protected cultivation.

The family Solanaceae consists of 85 genera, which include both tuberiferous and non-tuberiferous ones.  Brinjal (Solanum sp.), chilli (Capsicum sp.) and tomato (Lycopersicon sp.) are the major fruit vegetables under the family.  In all genera, fruit is an indehiscent berry.
 
A key for the identification of the above  three genera are furnished below:
    A.    Anthers connivant in a cone, longer than filaments
    B.    Anthers dehisce by apical pores or short slits, leaves entire, lobed or pinnatifid : Solanum
    BB.    Anthers dehisce introsely by longitudinal slits, the tips empty, leaves pinnatiset : Lycopersicon
    AA.    Anthers not connivant in a cone, not larger than the filaments, dehisce by lateral slits : Capsicum

Crops belonging to family Cucurbitaceae are generally known as ‘Cucurbits’. It consists of a wide range of vegetables either used for salad purpose (cucumber) or for cooking (all gourds), pickling (West Indian gherkin) or as dessert fruit (muskmelon, water melon) or candied or preserved (ash gourd).  As a group, cucurbits occupy the largest area in India and in other tropical countries. Its use is not primarily because of calories, minerals or vitamins since they are generally low to moderate in nutrients with a few exceptions like bitter gourd (rich in vitamin C- 96mg/100g), pumpkin (vitamin A 1600 IU/100g ), Kakrol (high protein  3.1g/100g,), parwal and chow chow (calcium- 531 mg and  140 mg / 100 g respectively). From the nutritional point of view, cucurbit seeds are valued for their high oil and protein contents.  Seed proteins of cucurbits are comparable to that of legumes and are richer in methionine.

Okra is predominantly a crop of tropics and subtropics.  It occupies fifth position, next to tomato, in area under vegetables in the country with a production of 33.24 lakh metric tonnes from an area of 3.47 lakh hectares.  The crop is cultivated for its young tender fruits, used in curry and soups after cooking. It is a good source of vitamins A and B, protein and minerals. It is also an excellent source of iodine and is useful for the treatment of goitre.  Fruit is useful against genito-urinary disorders, spermetorrhoea and chronic dysentery. Fruits are also dried or frozen for use during off-season.  Dried fruit contain 13-22% edible oil and 20-24% protein and is used for refined edible oil.  Dry fruit skin and fibres are used in manufacture of paper, card board and fibres.  Root and stem are used for clearing cane juice for preparation of jaggary.

Peas and beans belonging to the family Fabaceae (Syn. Leguminosae) are delicious and preferred vegetables grown throughout the world. These include cool season vegetables like pea, French bean, lima bean, broad bean and tropical vegetables like cowpea, hyacinth bean, winged bean, jack bean, sword bean etc.  These are integral components of sustainable agriculture due to their ability to fix atmospheric nitrogen and to improve soil properties. Legume vegetables are rich in protein and essential amino acids and have significant role in combating malnutrition among poor people and vegetarians.

Vegetables belonging to the family Brassicaceae (Syn: Cruciferae) are known as Cole crops.  These are the most widely grown vegetables in temperate and sub-tropical zones.  The word ‘Cole’ comes from abbreviation of word ‘caulis’ meaning stem.  Cole crops are a group of highly differentiated plants originated from a wild plant Brassica oleracea var. oleracea (=B. sylvestris L.) commonly known as “Wild cliff cabbage” or “colewort”, through mutation, human selection or adaptation. Cole crops include cabbage, cauliflower, knol khol, Brussels sprouts, Chinese cabbage, sprouting broccoli, kale etc. of which cabbage and cauliflower are the most popular and widely grown.

Bulb crops include onion, garlic, leek, shallot, welsh onion and chive all belonging to the genus Allium.  This genus was earlier included in the family Liliaceae due to its superior ovary.  It was later shifted to Amaryllidaceae as flowers are born in a bracted umbel on top of a scape.  Being the typical genus in the family Amaryllidaceae, a new separate family status was given to all the specious under Allium as Alliaceae.

Radish, turnip, carrot and beet root are major root crops grown in the country.  In addition, root crops like rutabaga, parsnip, salsify, chervil and celeriac are grown in a limited scale in different areas. Though the crops belong to different families, their cultural requirements are uniform.  Common features of root crops like radish, turnip, carrot and beet root are:

Potato is fourth major food crop after rice, wheat and maize in the world.  It produces the highest dry matter, well balanced protein and more calories/unit area and time.  Unlike other food crops, potato tubers contain vitamin-c (17 mg/100 g). It provides carbohydrates, minerals, fibre and a number of vitamin-B groups.  Potato protein is comparable to that of milk and egg.  Unlike European countries, in tropics and sub-tropics, the crop is of short duration and fits well in intensive cropping system.  It can be grown in a wide range of climatic and soil conditions and tubers are available throughout the year. Tubers can be left un-harvested in the soil for some time and are also suitable for long distance transport and storage. Several products like chips, flakes, French-fries, finger chips, granule, disc, cubes and flour are made out of potato tubers.

Tropical tuber crops are an important group of subsistence crops in tropical and subtropical zones.  Carbohydrates synthesised and stored in the form of starch in underground tubers are used as food by millions in under-developed countries.  It is also used as raw material by many industries.  Cassava, sweet potato, Chinese potato, edible aroids like elephant foot yam, taro, tannia and yams like greater yam, lesser yam and white yam are major tuber crops  grown in India.

Tuber crops are mainly grown as rainfed with minimum cost of production.  All are propagated through vegetative means and require fertile and well drained loose soil for proper root development. All roots crops require high dose of potassium for high productivity.

Leaf vegetables are rich sources of provitamin-A, vitamin-C and minerals like calcium, iron etc.  They also provide roughage required in human diet.  The Indian Council of Medical Research (1984) recommended a daily intake of 100 g and 40 g of leaf vegetables in the diet of woman and man, respectively. Amaranth, beet leaf, spinach, fenugreek, cabbage etc. are the major leaf vegetables grown in the country. In addition, a number of under-utilized annual crops are also grown as leaf vegetables in specific regions. Tender stems and leaves of a number of perennial crops are rich sources of vitamins and minerals and are used for cooking.  The major annual leaf vegetables have a few features in common:

Vegetables which are consumed raw without cooking are known as salad crops.  In temperate regions, a large number of quick growing cool season crops like lettuce, celery, parsley, endive, chicory, chervil, cress, water cress etc. are consumed as raw. Only lettuce and celery are cultivated on a commercial scale in developed countries.  Growing awareness on nutritional values of raw vegetables and also health consciousness of people resulted in increased consumption of salad vegetables in tropics too.  Vegetables like onion, cucumber, tomato, carrot, radish, beet root, cabbage, capsicum, melon etc. are used as salads without cooking.

Perennial vegetables live/survive in field for several years and go on yielding vegetables without much care and attention.  They are usually planted on the side of kitchen garden without much interference with tillage operations of other annual crops.  Tender leaves, shoots, fruits or tubers of a number of perennial crops are used for vegetable purpose in different agro-climatic conditions. They may be trees or shrubs as in bread fruit, jack fruit, drumstick, etc. or bushes as in colocasia or trailing plants as in yams, chow-chow and ivy gourd.

Current Status of Seed Production

Organized seed production in the country became possible with the formation of National Seed Corporation (NSC) during 1963, which paved the way for a sound seed industry to come as a consequence of the introduction of hybrid technology during 1961-65. The release of high yielding dwarf varieties of wheat and rice by the 1960’s gave further impetus to the growth of the seed industry in the country. For the total area under cultivation of 26.7 m hac and 44.8 hac of wheat and rice respectively, the seed requirement for these two crops alone come to 32 lakh tones and 13 lakh tones respectively of which the varieties contribute about 98 per cent and the hybrids 2 per cent. Only about 10-15 per cent of the total requirement is met by the seed producers leaving the balance for the farmers to manage and the seed producers have to grab the opportunity to supply quality seed materials in order to increase the production.

2.1 Rice

Rice is the staple food for the largest number of people on the Earth. According to an estimate, the global rice production must reach 800 million tonne from the present 91.04 million tonne in 2005-06 to meet the demand in 2025. It’s area is 37% of the total area under food grains as against 20% under wheat, another important food crop. But globally it stands next to wheat in harvested area.As the irrigated rice contributes more than 75 per cent of the total rice production, enhancing its yield potential would be key to meeting the global rice requirement for an additional 215 million tonne. To achieve the target yield, rice varieties with a yield advantage of about 20 per cent over popular and widely adapted rice varieties under tropical conditions must be developed. Experience in China, India, Vietnam, the Philippines, Bangladesh and several other countries clearly indicates that hybrid rice technology offers readily available option to meet this challenge.

3.1 Redgram or Pigeon Pea

In any production programme, the importance of quality seed needs hardly be emphasized. In fact, the major bottleneck in the pigeon pea cultivation programme is the restricted or poor availability of quality seeds of the desirable varieties. The seed has been considered as the ‘vehicle of change’. With better attention paid to their interaction among water, fertilizer and seed of improved varieties, the production can be maximized. Although a numbers of improved varieties of pigeon pea have been released since 1970, organized seed production programmes have been rather limited. Most of our national efforts in this direction continue to be centralized on cereal crops like wheat, rice and hybrid millets. Moreover, the benefits of the current research will not reach the farmers unless large-scale seed multiplication programmes are organized. Most farmers continue to use seeds of traditional varieties and consequently have not been able to expedite the higher production potential of the new strains.

4.1 Mustard 

The principle oil yielding rape seed & mustard sp. cultivated in India are

5.1 Jute Seed Production 

Jute ranks next to cotton as the most important natural fibre and it recognized as the ‘golden fibre’. Its products being biodegradable and environment friendly in contrast to synthetic substitutes, a renewed interest in this natural fibre has been generated in the recent past throughout the world. Important characteristics of jute fibre are its silky lustures, high tensile strength, low extensibility, considerable heat resistance. Because of its great abundance and shortage of cotton, jute is blended with cotton and jute/cotton blended yarns are produced mainly to take advantage of the lower price of jute fibre (Doraiswamy et al., 1998). Several diversified product is also made from jute. Since currently the paper industry has been using it as a raw material for paper. It is also being used in geotextile. The jute sticks are largely used as fuel and also for making gun powder.

Potato is an important crop of the world and grown in almost all the states in India. Apart from India, potato is grown in more than 100 countries but the intensity of cultivation varies considerably. For example in the Netherlands 19.6% of the total arable land is cultivated with potatoes. The figures for Germany, Peru and USA are 10.1%, 5.6% and less than 1% respectively. India ranks fourth in area (1.29 m ha) and third in production (25.23 m ton) in the world. The productivity of potato depends mainly on the quality and quantity of planting materials and the agronomic management practices adopted. Most of developing countries including India experience release of high yielding varieties, development of adequate agronomic and pest control measures but the gap between supply and demand of good quality adequate quantity seed has to be the major constraint in increasing its productivity. The seed production in India is mainly confined to the North-Western part both in the hills and the plains, because of favourable weather and low incidence of aphids (vectors responsible for viral diseases) in this regions.

Sir Alexander Ogston (1880) first isolated Micrococci in pus and in 1883 he subdivided them into two groups i.e. Staphylococcus and Streptococcus. He also first proposed the name ‘Staphylococcus’ (Greek ‘staphyle’ means bunch of grapes and ‘kokkos’ means berry). Experiments of Bumm (1885), Garre (1885) and Bockhart (1887) established its relationship with human infections. As well as Nocard (1887) first isolated Staphylococcus from mastitis in sheep and found its pathogenic significance in animals.

Properties of Genus

Morphology : Staphylococci are gram positive cocci, capsulated, non-sporing and non-motile. Each coccus cell is 1µm in diameter.  They are arranged in a group or grape like cluster as cell division occurs in more than one plane. During preparation of smear and staining the cluster is sometimes broken and cocci are seen in pair or single (Fig. 1).

Staphylococcal capsule is polysaccharide in nature. The capsule can inhibit phagocytosis and helps in virulence.

 Staphylococcal cell wall contains three major components i.e. peptidoglycan (PG), teichoic acid (TA) and surface proteins.

Rivolta (1873) first described the chain forming cocci in pus collected from the equine infection. Later Rosenbach established the genus ‘Streptococcus’. Nocard and Mollereau (1887) first observed the relationship between the bovine mastitis and Streptococcus agalactiae.

Properties of genus

1. Morphology : Streptococci are gram positive cocci, capsulated, non-sporing and non-motile. Each coccus cell is 1µm in diameter.  They are arranged in a pair or chain of cells as the cell division occurs in one plane (Fig. 1). The chain formation and the chain length are variable. Streptococcus equi ssp equi is a constant chain producer, other species are not. The chain length is shorter in artificial media than natural one. Young cultures are gram positive whereas the bacteria present in the pus and older cultures in the laboratory are often stained as gram negative. 

Streptococcal capsule is polysaccharide in nature. It can be subdivided into different antigenic types (e.g. S. agalactiae, S. pneumonae). However capsules of S. equi, S. pyogenes are made of nonantigenic hyalu-ronic acids containing repeating units of glucuronic acid and N-acetyl-glucosamine. Synthesis of the polymer involves the products of three genes, hasA, hasB, and hasC, which are all in the same operon.

In 1850, Bacillus anthracis was first reported by three individuals in two different countries i.e. Delafond (who may have found them as early as 1838) and Davaine in France, Pollender in Germany. However, they could not establish the relationship between the disease and the bacterium. Absolute proof of the anthrax etiology as B. anthracis was established by Robert Koch in 1876-77. The name Bacillus anthracis was first coined by Cohn (1875) and the disease ‘anthrax’ was first named by Hippocrates (5th century B.C.). In Greek language meaning of anthrax is ‘coal’ referring to the black coloured skin or blood in affected animals.

B. anthracis organism has certain historical importance:

a)   Anthrax is the first disease identified to be caused by a bacterium.

b)   Robert Koch first isolated the organism and reproduced the disease in experimental animals. He proposed his postulates (Koch’s postulate, 1876) based on his experiments related to this organism. It later became a fundamental milestone of all microbiological works related to the infectious diseases.

c)   Louis Pasteur first used heat attenuated culture of B. anthracis as vaccine in a group of sheep in 1881 at Pouilly-le-Fort. He cultured the organism at 42-43^oC in presence of oxygen. The bacteria did not produce spores and became attenuated.

d)         First concept of bacterial antagonism was provided by Louis Pasteur and Joubert based on their work on this organism. Injection of other unidentified bacteria along with B. anthracis can prevent anthrax in animals
.

The genus Clostridium belongs to the family Clostridiaceae. The genus name was originated from the Greek word ‘kloster’ means spindle, referring to their individual rod shape. Clostridia are gram positive, large, sporulating anaerobic rods (except C. piliforme which is gram negative). At present, there are more than 200 numbers of species under the genus Clostridium. Among them, 15 species can produce potent toxins and are considered as pathogenic for animals and human. The animal pathogenic Clostridia can be classified as neurotoxic, histotoxic and enteric.

In 1882, Robert Koch first isolated the organism, stained with alkaline methylene blue and vesuvin as counter stain and proved its etiologic relationship with Tuberculosis.  Ehrlich first developed acid fast stain in 1882 and used for better staining of the bacteria which was adopted by Robert Koch. Later this staining technique was modified by Ziehl-Neelsen, accordingly it is now a day known as Z-N staining. In 1890, Koch prepared a glycerine broth extract of the tubercle bacillus, known as ‘tuberculin’.

      He tried to prepare it as a curative agent; however, it was used later in diagnosis. In 1895, Johne and Frothingham described the first case of paratuberculosis in cattle, later known as ‘Johne’s disease’. Although, the causative agent was first isolated by Twort and Ingram in 1910.

            In India, bovine Tuberculosis was reported from several states since 1959 (Dhanda and Lal, 1959). Whereas bovine paratuberculosis was first reported by Nanda and Singh (1940) in Hissar, Haryana.

This family Enterobacteriaceae belongs to the order Enterobacteriales. The family comprises 25 genera. Among them there are 10 genera consistently found pathogenic for animals, birds and human. These genera are mentioned below (first 10 are consistent pathogenic).

In 1886, Escherich observed Campylobacter like organisms in stool samples of children with diarrhoea. In 1913, McFaydean and Stockman first confirmed them as Campylobacter in foetal tissues of aborted sheep. Confirmatory tests were also carried out by Smith in 1918 when similar organisms were isolated from aborted bovine foetuses. The organism was then known as Vibrio foetus. In 1963, due to certain differentiating characteristics, the organisms were separated from Vibrionaceae family and the new genus Campylobacter (means ‘curved rod’) under Campylobacteriaceae family was proposed. 

Properties of genus

1.   Morphology :  Campylobacter is gram negative, comma shaped rods specially in infected tissues and young cultures. The size is 1.5-4 µm by 0.5 µm. When two bacterial cells are found together in a microscopic field, it looks like ‘S’ or ‘wing of gull’ (‘flying seagull’). However in older cultures, the chains of organism appear as long spirals. They are motile by single unipolar/ bipolar unsheathed flagella. Motility is darting or corkscrew type, best observed by dark field microscopy. They are non-sporing. Some species contains S-layer (surface layer), a paracrystalline protein structure composed of S-layer proteins (SLPs). It is external to the outer membrane. It helps the bacteria in immune evasion.

Clinical conditions similar to Brucellosis have been described since the time of Hippocrates (450 BC). J. A. Marston first described brucellosis as gastric remittent fever in 1861 at Malta (Marston, 1861). Sir David Bruce in 1886 first isolated little coccobacillus from an infected soldier’s spleen. However he isolated the bacteria in a pure culture in 1887 and named Micrococcus melitensis (Bruce, 1889). Later the genus was renamed as Brucella in his honour. Similarly, Bang and Stribolg first isolated Brucella abortus from abortion material of a cow (Bang, 1897). Traum in 1914 isolated the Bacillus abortus suis. Presently we know it as Brucella suis. In 1953, Brucella ovis was first isolated in New Zealand (Budlle and Boyes, 1953) from the aborted material of sheep. Carmichael and Bruner in 1968 first isolated B. canis from the aborted placenta of a dog.

            In India first report of ‘Contagious abortion’ by Brucella was found from annual report of Imperial Veterinary Research Institute (presently Indian Veterinary Research Institute), Mukteswar, Uttarakhand (Anonymous, 1918). Seroprevalence of Brucellosis is reported from various states of India afterward (Polding, 1942; Sethi et al., 1971 etc.).

Pasteurella and Mannheimia species are gram negative small coccobacilli under family Pasteurellaceae. Trevisan (1887) coined the generic name Pasteurella for the first time and it was accepted worldwide. Lignieres (1900) proposed the specific name for each organism according to the species of animal host: Pasteurella aviseptica for fowls; P. suiseptica for pigs; P. boviseptica for bovines; P. oviseptica for ovines and P. leptiseptica for rabbits. Finally, Rosenbuch and Merchant (1939) proposed a single species Pasteurella multocida and it is in use till date. 

      Mannheimia haemolytica was earlier known as Pasteurella haemolytica, but because of variations in cultural, pathological and 16S rRNA sequence, it is placed in separate genus.

Properties of genus

Morphology : P. multocida is a non motile, non spore-forming short rod or coccobacillus, 0.2-0.4 by 0.6-2.5 µm in size. Repeated laboratory subcultures or cultures grown under unfavourable conditions tend to be pleomorphic and longer rods or filamentous forms appear. In tissues, exudates and recently isolated cultures, the organism shows the typical coccobacillary forms. It is a gram-negative organism and, in fresh cultures and animal tissues, gives typical bipolar staining (Fig.1), particularly with Leishman or methylene blue stain.

Lucke (1862) first described that the bluish green discolouration of surgical dressing is associated with the presence of small vibrio like organisms. Latter Gessard first isolated the organism as Pseudomonas in 1882.

Properties of Genus

1. Morphology : They are Gram negative straight or curved rod, motile by one or more polar flagella. Usually it is 1.5 µm in length and 0.5 µm in width. Longer filamentous forms are sometimes observed. The bacteria are non- acid fast, non- sporulating and uncapsulated. Pili on the bacterial surface are detected. Environmental and strains present within tissue can produce slime. The slime is composed of glycolipoprotein (GLP) and polysaccharide of LPS.
    
2. They are strict aerobe.

Classification : Pseudomonas belongs to class Gamma-Proteobacteria, order- Pseudomonadales, family- Pseudomonadaceae.  Previously Pseudomonas included two group of bacteria viz. Fluorescent group and Pseudomallei group. Recent classification system included this Pseudomallei group into a new genus known as Burkholderia. Important species of Pseudomonas are:

The genus was named after Morax who first isolated the organisms from human conjunctivitis in 1896.

Properties of genus

1.   Morphology :  Moraxella are gram negative, small rods occurring in pair (diplobacilli). The aged cultures exhibit pleomorphism, occurring in pairs or chains as short, plump rods with rounded ends. Some strains may appear as cocci. The capsule is present in fresh isolates of some species (except Moraxella catarrhalis). They are non-motile and non-sporing. Moraxella bovis contains numerous type IV fimbriae on its surface.

2.   Moraxella is aerobic, fastidious and non-fermenting in nature. However, some strains prefer anaerobic condition for their growth.    

3.   Classification : The genus Moraxella belongs to the Moraxellaceae family. Previously it was known as Branhamella. Most of the species are commensal except a few, which have disease producing capabilities. Important species are M. bovis, M. ovis, M. catarrhalis, M. boevrei, M. canis, M. caprae, M. caviae, M. cuniculi, M. phenylpyruvica.

4. Resistance : Resistance to physical and chemical agents is not remarkable. They are susceptible to desiccation and do not survive long outside the host. The beta- lactam antibiotic resistance is observed among M. catarrhalis isolates from clinical cases. This resistance is associated with the production of beta-lactamase enzyme.