eChapters

1.1.1 Definition and Scope of Soil Science

Definition: Soil science encapsulates the scientific exploration of one of Earth’s most vital components—soil. It goes beyond the everyday understanding of soil as mere dirt, positioning it as a dynamic and complex system that supports life. At its core, soil science is an amalgamation of various scientific disciplines, each contributing to the comprehensive study of soil. This multidisciplinary approach ensures a holistic understanding that extends far beyond the surface.

Soil science is not confined to the physical substance beneath our feet; rather, it embraces a nuanced perspective that involves decoding the intricate language of the soil. It is the science of uncovering the secrets embedded in the Earth’s outer layer—examining its history, composition, and the myriad interactions that shape its character

Systems biology examines living organisms as integrated and interconnected systems rather than as isolated genes, proteins, or metabolic pathways. This chapter introduces the historical development, principles, and major components of systems biology. It explains biological networks, pathway architecture, transcriptome analysis, gene-expression analysis, and interactions among genes, proteins, enzymes, and metabolites. Network-based approaches provide a framework for understanding complex biological processes and predicting cellular responses. The chapter also introduces synthetic biology and synthetic networks and discusses applications of systems biology in medicine, biotechnology, agriculture, and environmental research. Advantages, limitations, computational requirements, and future developments are considered as systems approaches continue to expand biological understanding.

Fungal and parasitic infections represent major health challenges in Indian aquaculture, impacting both freshwater and marine systems across diverse climatic regions. These pathogens significantly affect fish health and productivity, often causing substantial losses in high-density farming systems. Their complex life cycles and often nonspecific clinical symptoms make diagnosis and control particularly difficult. Effective detection, timely treatment, and preventive biosecurity are essential to maintaining sustainable aquaculture practices in India.
Fungal pathogens such as Saprolegnia, Achlya, and Branchiomyces are commonly encountered in Indian aquaculture. These opportunistic fungi typically infect fish weakened by environmental stress, physical injury, or concurrent bacterial infections. Among these, Saprolegnia spp. are most frequently implicated, especially in carps, catfishes, and ornamental fish. Infected fish often display white or greyish cotton-like growths on the skin, gills, or eggs.
Field-level identification relies on observation of external lesions, erratic behavior, and increased mortality. Microscopic examination of skin scrapes or gill biopsies mounted in saline or potassium hydroxide (KOH) can reveal fungal hyphae, which are long, filamentous, and typically non-septate or sparsely septate.
Fungal cultures are grown on Sabouraud Dextrose Agar (SDA) or Potato Dextrose Agar (PDA), often supplemented with antibiotics to suppress bacterial contamination. Incubation at 25–30°C allows colonies to develop, which can be characterized by morphological and microscopic traits. Molecular diagnostics, including PCR targeting fungal ITS regions, are increasingly utilized in advanced laboratories such as ICAR institutes and state fisheries departments.

Introduction

Colocasia esculenta (L.) Schott, also known as taro, belongs to the family Arecaceae. Taro is believed to have originated in Southern or South-East Asia, and to have been dispersed to Oceania through the Island of New Guinea to many centuries ago but cultivated in Asia for more than 10,000 years. Taro is considered as an important vegetable grown throughout India. Taro is herbaceous perennial plants with a large corm on or just below the ground surface and can be grown in the ground or in large containers. They can be grown in almost any temperate zone as long as the summer is warm.

Taro root contains very significant amount of dietary fibre and carbohydrates, as well as high levels of vitamin A, C, E, B6 and folate, as well as magnesium, iron, zinc, phosphorus, potassium, manganese and copper. Thogh negligible, the plant is also known to provide some protein in our diet. As Taro is a great source of fibre and other nutrients, it offers a variety of potential health benefits, including improved blood sugar management, gut and heart health.

Globally, taro is grown in an area of 1.6 m ha producing 11.66 mt with an average productivity of 7.25 t ha^-1 (FAO, 2009). The plant can be grown in wide range of climatic condition but during growth period taro is prone to attack by at least twenty- three (23) pathogens, of which, only a few causes serious reduction in the potential yield of the crop. Some of the mentionable diseases that commonly occurs and causes yield loss of the plants are as follows:

Introduction

Plant parasitic nematodes are important pests, causing major damage to the world’s food and fibre crops. The management of nematodes is more difficult than that of other pests because nematodes mostly inhabit the soil and usually attack the underground parts of the plants. Nematodes in soil are subject to infections by bacteria and fungi. This creates the possibility of using soil microorganisms to control plant-parasitic nematodes. Biocontrol of nematodes was first studied by Duddington (1951). The development of biological control agents is also considered an effective alternative for nematode control on vegetables (Van Gundy, 1985; Kerry, 1987). There are more than 200 species of nematophagous fungi described. Based on the infection mechanism, they are commonly subdivided into three main groups: the nematode-trapping fungi that captures free living nematodes using specialized morphological structures (i.e., traps), the endoparasitic fungi that infects nematodes using adhesive spores, and the egg- and cyst-parasitic fungi that infect these stages with their hyphal tips (Barron, 1977). The nematophagous fungi that have received most attention for biological control of plant-parasitic nematodes include various species of the nematode-trapping fungi Arthrobotrys spp. (Stirling and Smith, 1998), and the egg-parasitic fungi Pochonia chlamydosporium (Kerry, 2001) and Paecilomyces lilacinus (Gaspard et al., 1990).

ABSTRACT

Biotransformation is an essential step in the elimination of drugs and reduction of their toxicity. The use of fungi in biotransformation reactions can provide information about the metabolism of new drugs and facilitate the attainment of necessary amount of metabolites for toxicological and pharmacological evaluation. Biotransformation studies require the right choice of the microorganisms and also of the culture conditions (pH, substrate, oxygen, salts, temperature, etc). The optimization of these procedures is essential to achieve good results. The fundamental aspects of drug biotransformation by fungi are discussed here as well as some applications showing that many fungi are used in biotransformation studies, mainly Cunninghamella species. Several species mimic the mammalian metabolism producing the same metabolites observed in humans.

Plant pathogens are known to cause yield reduction of almost 20 per cent in the principal food and cash crops worldwide (Oorke et al., 1994). These losses may be more severe when highly susceptible cultivars are widely grown in a particular region of the globe. The increased world’s population is posing a major global challenge to provide sufficient quatity of food with high quality fruits and vegetables. Nearly, 570 million US $ is now spent annually on research and development by the leading 15 agricultural Companies to combat with the important diseases of major food, fruits and vegetable crops. There are more than 150 active ingredients registered as fungicides worldwide (Mc Dougal, 1996). In the present era of intensive agriculture, fungicides play an important role in our fight against plant diseases and reduce the losses in yield and quality of farm produce. The global fungicide sale has been estimated to be $ 6.0 billion US. The cereal and vine industries of the Western European have become largest fungicide market followed by North America. However, the fungicide use is not intensive in Asia and the new world.

This article presents the historical development of fungicides, mode of their action, development of resistance to fungicides, fungicidal residue and chemical control of various diseases of horticultural and plantation crops.

Fungus is member of group of eukaryotic organisms that includes yeasts and molds. The fungi are heterotrophs and they acquire their food by absorbing dissolved molecules by secreting digestive enzyme in the environment. It is present in common place in the environment and some are normal inhabitants of the skin, gastrointestinal tract and other mucous membrane surfaces. Generally if birds immunity is intact and fully operational then it will overcome the fungal infection in most situations, In case of compromised immune system it will cause development of serious infections. Paramount to properly managing fungal infections in avian species is the ability to recognize infection early in the course of disease, to administer appropriate antifungal medications for the location and severity of infection, and to continually assess a patient’s response to therapy.

Clinical Symptoms

• White/brown cotton-like foci on the surface of the skin and/or gills

• Peritonitis

• Extensive haemorrhage • Necrosis

• Adhesions

1. What is a characteristic feature of fungal cell walls?

a) Peptidoglycans

b) Ergosterol and polysaccharides

c) Antiphagocytic capsules

d) Fruiting bodies

2. How do fungi reproduce in tissues?

a) Binary fission

b) Budding

c) Simple division of round, yeast-like forms or slender, tubular hyphae

d) Spore formation

The fungal exometabolome represents the collection of metabolites secreted by fungi into their surrounding extracellular environment. This chapter introduces the concept of the fungal exometabolome and distinguishes it from the intracellular endometabolome. It discusses the composition of extracellular metabolites, factors influencing their production, methods used for exometabolome analysis, and their biological functions. Fungal exometabolites can contribute to communication, nutrient acquisition, competition, host interactions, and environmental adaptation. The chapter also examines industrial and medical applications and the role of fungal exometabolomics in systems biology. Advantages, limitations, analytical challenges, and future perspectives are discussed to demonstrate the value of extracellular metabolite analysis in fungal research.

Summary

Nanotechnology is an interdisciplinary areas of science and technology which refers broadly to a field of applied science and technology whose unifying theme of control of matter is on the molecular scale that integrates material science and biology. Due to their advantages over non-biological systems, several research groups have explored the use of biological systems for the synthesis of nanoparticles. Among the different microbes used for the synthesis of nanoparticles, fungi are efficient candidates for fabrication of metal nanoparticles both intra-and extracellulary. The nanoparticles synthesized using fungi present good polydispersity, dimensions and stability. The potential applications of nanotechnology and nanoparticles in different fields have revolutionized the health care, textile and agricultural industries and  they are described in present chapter.

For growing fungi, a wide range of media are used. Media affect colony morphology and color. For utilizing different carbon sources some fungi lack the necessary enzymes. For growth and reproduction all fungi require several specific elements. The requirements for growth are generally less specific than for sporulation, so it is often necessary to try several types of media when attempting to identify a fungus in culture. Sporulating cultures should be used because repeated transfers of a pathogen on artificial media usually result in loss of sporulation or pathogenicity or both. Transfer should be made using spores and cultured alternately on nutrient rich and poor culture media. Most fungi thrive on potato dextrose agar (PDA), but in some fungi excessive mycelial growth is obtained at the expense of sporulation. Similarly, wood-inhabiting fungi and dematiaceous (dark pigmented) fungi often sporulate better on Corn meal agar (CMA) or Oat Agar, both of which have less easily digestible carbohydrate than PDA. Cellulose-destroying fungi grow on a weak medium such as Water Agar (WA) or Potato Carrot Agar (PCA). By adding pieces of tissue, such as filter paper, wheat straw, rice, grains, leaves or dung, often produces good sporulation dependent on the organism grown. Some special methods of inducing sporulation in fungi.

Fungi are achlorophyllus so they have to depend on other organisms hence heterotrophic nutrition. Depending on the nutrition, fungi are classified as Saprophytes, Parasites and Symbionts.

3.1 Saprophyte (sapros = rotten; phyton = plant)

Fungi which get their nutrition only from dead organic are called saprophytes ex: Saprolegnia, Rhizopus, Mucor, Alternaria etc.

3.1.1 Facultative saprophyte (Facultas = ability)

Ability of a fungus to become saprophyte. It is a parasite ex. Ustilago

3.1.2 Obligate saprophyte (obligate = to bind itself)

When they strictly get their food only from dead organic matter and can never become parasites are called obligate saprophyte ex. Mucor.

Introduction

Seed, the basic input of crop production technology, is exposed to various stress factors right from its formation to the completion of its germination. Even after germination, the stressed seeds may fail to emerge into a healthy plant and thus, the subsequent seed formation is also affected both quantitatively and qualitatively.

The stress factors may be abiotic, biotic or mesobiotic. Environmental factors such as climatic parameters, nutritional deficiencies, soil factors and conditions of storage are the examples of abiotic stress factors. Insects, fungi, bacteria, nematodes and other plant parasites constitute biotic stress factors whereas viruses, viroids and virusoids and similar agencies are the examples of mesobiotics factors that bring about stress over the seed. Apart from these conspicuous causes of stress, there are certain other factors also, which may affect the influence of stress over the total performance of the seed. For example, the crop improvement efforts bring about changes in seeds quality that can have considerable effects on the vulnerability of the seed to invasion by various biotic factors.

Introduction

Fermented foods and beverages comprise an indispensable part of the human diet. They can be generally defined as those foods and beverages produced via controlled microbial growth and conversion of various substrates using either enzymes or as whole cell itself, as shown in Figure 1.

Definition
Fungi are eukaryotic, spore bearing, achlorophyllus, heterotrophic and thallophytic plants with varied forms and habitats, representing heterothallic or homothallic types of sexuality with characteristic sexual and /or asexual means of reproduction without tissue differentiation.
General Characteristics of Fungi
1. Thallus
The body of the fungus is called as Thallus, which is without stem, root and leaves. It may be Plasmodial, Pseudoplasmodial , Pseudomycelial or Mycelial. A single thread like filament is called as hypha. A hypha is made up of a thin, transparent tabular wall filled or lined with a layer of protoplasm.

A group of hypha constituting the body of fungus is called as mycelium may be septate or aseptate. i.e coenocytic.
(a) Coenocytic or Nonseptate or Aseptate Mycelium: When mycelium is not divided by cross walls called as Coenocytic mycelium. Depending upon the nature of parasitism with the host plant, mycelium is either ecotophytic or endophytic.
b) Septate Mycelium: When mycelium is divided by cross walls or septa called as septate mycelium.

Introduction
Fungi are a diverse group of eukaryotic organisms that play a significant role in ecosystems, including their function as pathogens in plants. They can cause a wide range of diseases that affect plant health and agricultural productivity. Understanding the characteristics, life cycles, and impact of phytopathogenic fungi is crucial for effective disease management.
General Characteristics of Fungi
Fungi are distinguished from plants and animals by several key features:
Cell Structure: Fungi have a complex cell structure with a rigid cell wall made primarily of chitin, which differs from the cellulose found in plant cell walls.
Nutritional Mode: Fungi are heterotrophic organisms that obtain nutrients through external digestion. They secrete enzymes into their environment to break down complex organic matter into simpler compounds, which are then absorbed.

9.1. Fungi useful against plant disease pathogen

9.1.1. Trichoderma viride

Trichoderma viride (Fig. 231) fungus is used as a bio-fungicide. It is used for seed and soil treatment for suppression of various diseases caused by fungal pathogens. It is also a pathogen in its own right,causing green mould rot of onion.

The fungicidal activity makes T. viride useful as a biological control agent against plant pathogenic fungi. It has been shown to provide protection against pathogens like Rhizoctonia, Pythium and Armillaria.

It is found naturally in soil and is effective as a seed dressing bioinoculant in the control of seed and soil-borne diseases including Rhizoctonia solani, Macrophomina phaseolina and Fusarium species. When it is applied to the seed, it colonizes the seed surface and kills not only the pathogens present on the cuticle, but also provides protection against soil-borne pathogens.

3.1. Plant diseases caused by soil borne fungi

3.1.1. Clubroot Disease causing fungi

Plasmodiophora brassicae (Fig. 125)

It infects Crucifers host species.

Infected plants in the begening shows pale green to yellowish leaves, which later on show wilting in the middle of hot, sunny days, and recovering during the night. Young plants may be killed by the disease soon after infection, whereas older plants may remain alive but become stunted and fail to produce marketable heads.

The most characteristic symptoms of the disease appear on the roots as spindle-like, spherical, knobby, or club-shaped swellings. The swellings may be few and isolated or they may coalesce and cover the entire root system. The older and usually the larger clubbed roots disintegrate before the end of the season because of invasion by bacteria and other fungi.