eChapters

ABSTRACT

Endophytes are microorganisms that live inside the host plant tissues without causing symptoms of disease. There has been a crescent interest in the prospecting of these microorganisms as sources of novel and bioactive natural products. In fact, a significant number of interesting natural products have been reported in the last years. In this chapter some aspects regarding the endophytes are detailed: the relationship with their host plants, isolation, preservation, taxonomy, cultivation, frequently isolated strains, tropical endophytes, novel structures isolated and also their biological activities.

Key words: natural product, endophytic fungi, plant fungus interaction, secondary metabolites.

ABSTRACT

Soil borne fungal pathogen causing root diseases of vegetables are difficult to control by chemical methods. The existing biocontrol bacteria are not very effective in control of soil borne fungal pathogens. As such very less number of bacterial biopesticide is available commercially to control the fungal pathogens. Increasing concerns in recent years about human health and environmental problems due to chemical pesticides, couple with increasing pest resistant to chemical, have led to a reappraisal of our approach to control pest and disease in crops. The trends now are towards a management concept in which the best combination of tools is used to manage plant diseases below economic thresholds with minimal risk to human health and environment. The modern management concept includes extensive use of biocontrol agents which are harmless to non-target organisms. Development of effective technology for control of pest and disease by using microbial resources of a region to enhance the quality of ecosystem is a potential alternative approach to chemical control of plant diseases. In such strategy, search for microorganisms and biological system is an important prerequisite prior to development and practical exploitation of biocontrol. Rhizosphere microorganisms are shown to be perspective candidate for biocontrol agent as they provide the front line of defense for plant roots against the attack by various plant pathogens causing the most diseases of vegetables and crops. Chemical control of soil-borne fungal pathogen had been the subject of growing concern because of their adverse effect on the environment and emergence of chemical pesticide resistant to plant pathogen, moreover, soil borne pathogens are very difficult to control. Crop rotation, breeding for resistant plant varieties and application of pesticides are insufficient to control root diseases of important plants because they survive as sclerotia and has got wide host range.

ABSTRACT

Plant growth promoting (PGP) bacteria play an immense role in promoting crop growth mainly by direct mechanisms such as N_2-fixation, phosphate solubilization and phytohormone production and indirectly may help to suppress pathogens or contribute to enhance absorption of nutrients leading to increase yields. The N₂fixers are grouped based on their niche adaptation as endophytic nodular symbionts (Rhizobium spp.), free living (Azotobacter spp.), associative symbionts (Azospirillum spp.) and endophytic non-nodular symbionts (Azoarcus and Gluconacetobacter diazotrophicus). In the recent past, phosphate solubilizing and phytohormone synthesizing bacterial communities also gained momentum.

ABSTRACT

Methylotrophy is a phenomenon by which microorganisms derive energy, and in many cases, cell carbon from reduced molecules that have no C–C bond (also called C1compounds). This gains significance because of its unique mode of nutrition, the ability to utilize more than one metabolic pathway and its vast distribution among various groups of bacteria and yeasts. It is one of the earliest modes of energy metabolism present in microorganisms, through which microorganisms are able to utilize a wide range of compounds, which are considered unsuitable for most forms of life. In the present chapter we focus on various aspects of methylotrophy, and the application of methylotrophic bacteria in a spectrum of biological activities and commercial possibilities.

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.

ABSTRACT

A number of secondary metabolites are produced by cyanobacteria involving the non-ribosomal peptide biosynthetic pathway. Some of these compounds have potential biotechnological applications, whereas others (the cyanotoxins) are undesired due to their toxicity to animals. The occurrence of toxic cyanobacterial blooms in freshwater bodies that are used as source for human consumption, recreation and irrigation are frequent nowadays due to increasing artificial eutrophication of these environments. It is important to monitor toxin-producing strains in order to prevent the adverse effects caused by their toxins to human and animal health. Thus, the development of rapid and sensitive methods for the detection of cyanotoxins is important as they could be useful to monitor water supplies and contribute for watershed monitoring strategies. Current methods include cell counting, microscopic identification and toxin analysis by biochemical and analytical techniques. However, in recent years, molecular biology techniques, such as polymerase chain reaction (PCR), have been used to amplify specific regions within biosynthetic genes for rapid and sensitive identification of toxic cyanobacteria. The aim of this chapter is to provide an update of cyanotoxin biosynthesis and discuss the advances and limitations of molecular biology regarding its application as indicative of cyanotoxin production.

ABSTRACT

Bioinformatics is a critical tool in designing the molecular biology experiments. The xeroxing of specific part of genome needs correct primer designing. Primer designing has central role in molecular biology right from cloning, sequencing, gene expression profiling by real time PCR, genotyping by RFLP, SNP analysis by real time PCR and auto sequencer. In this chapter we are describing how to proceed for experimental designing right from data mining from GENEBANK to designing of primers for various common molecular genetic analysis work. The write up also describes in silico evaluation of primers, various off line commercial and non-commercial software, on line free software and trouble shootings in primer designing, The different strategy described in context of primer designing would be of immense use of researchers.

The effects of global warming and/or climate change are of concern both for the environment and human life. Evidence of observed climate change includes the instrumental temperature record, rising sea levels, and decreased snow cover in the Northern Hemisphere. According to the IntergovernmentalPanel for Climate Change (IPCC) Fourth Assessment Report, “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in [human greenhousegas] concentrations. It is predicted that futureclimate changes will include further globalwarming (i.e., an upward trendin global mean temperature), sea level rise, and a probable increase in the frequency of some extreme weather events. Ecosystems are seen as being particularly vulnerable to climate change. Human systems are seen as being variable in their capacity toadapt to future climate change. To reduce the risk of large changes in future climate, many countries have implemented policies designed to reducetheir emissions of greenhouse gas.

Phytochemicals are chemical compounds that occur naturally in plants (phyto means “plant” in Greek). Some are responsible for color and other organoleptic properties, such as the deep purple of blueberries and the smell of garlic. The term is generally used to refer to those chemicals that may have biological significance, for example antioxidants, but are not established as essential nutrients. Scientists estimate that there may be as many as 10,000 different phytochemicals having the potential to affect diseases such as cancer, stroke or metabolic syndrome. The potential of the phytochemicals have large scale pharmacological and biological activities such as antioxidant constituents (hydrolysable tannins, phenolic acid and flavonoids) of the plant materials for the care of health and protection from coronary heart diseases, cancer, anti-carcinogenic and anti-mutagenic effects. Varieties of herbaceous vegetables are protective against various diseases, particularly cardiovascular diseases. These herbaceous plants and species are harmless sources for obtaining natural antioxidants. Antioxidant constituents can delay or inhibit the oxidation of lipids and other compounds by inhibiting the propagation of oxidation chain reaction (Hussain et al., 2011)

Primarily, antioxidant effect is due to phenolic compounds such as phenolic acid, flavonoids and phenolic diterpenes and their mode of action for antioxidant compounds is due to its redox reaction properties which can absorb and neutralize free radicals by quenching singlet and triplet oxygen. Vitamins are organic substances necessary for metabolism. Human diet does not always contain the required amount of vitamins for the normal growth and maintenance of the body function and as such cannot produce enough quantity for their body metabolism, so it can be obtained from fruits, vegetables and foods. Deficiency of vitamins can cause serious human health diseases and sometimes, very small concentrations are required for maintenance of good human health.

Equipment

1. Adjustable pipette.
2. 20-ml glass beaker.
3. Atomic Absorption Spectrophotometer.

In chemistry, and especially in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic tail (chain), which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from triglycerides or phospholipids. When they are not attached to other molecules, they are known as “free” fatty acids. Fatty acids are important sources of fuel because, when metabolized, they yield large quantities of ATP. Many cell types can use either glucose or fatty acids for this purpose.

Nitrogen is a nutrient and occurs in many forms including ammonia, organic, nitrate and nitriteeach of which may be tested for in a variety of ways. Under normal circumstances, the nitrite form of nitrogen will not be present in large quantities due to its rapid oxidation orconversion to nitrate. The presence of large concentrationsof ammonia in a stream or lake can create a large oxygen demand. This demand is caused by the conversion of ammonia to nitrate. High concentrations of nitrate in waste water treatment plant effluent can cause algae to grow in large quantities.

Current status

For many years, the protein contentof foods has been determined on the basis of total nitrogen content, while the Kjeldahl (or similar) method has beenalmost universally applied to determine nitrogen content (AOAC, 2000).Nitrogen content is then multiplied by a factor to arrive at protein content. This approach is based on two assumptions: thatdietary carbohydratesand fats do not contain nitrogen, and thatnearly allof the nitrogen in the dietis present as amino acids in proteins. On the basis of early determinations, the average nitrogen (N) content of proteins was found to be about 16 per cent, which led to use of the calculation Nx6.25(1/0.16 = 6.25) to convertnitrogen contentinto protein content.

Carbohydrates are widely prevalent in the plant kingdom, comprising the mono, di-, oligo-, and polysaccharides. The common monosaccharides are glucose, fructose, galactose, ribose etc. The disaccharides, i.e., the combination of two monosaccharides include sucrose, lactose and maltose. Starch and cellulose are polysaccharides consisting of many monosaccharide residues. Cellulose is the most abundant organic compound on this planet since it forms part of the cell wall in plants.

Aldehydes (–CHO) and ketones (= CO) are active groups in carbohydrates. Carbohydrates contain many hydroxyl groups as well. The number of hydroxyl groups varies with the number of carbon atoms. Monosaccharides contain the free aldehyde or ketone group. Some disaccharides have the free aldehyde group (maltose) and some do not have the free ones (sucrose). The polysaccharides, starch and cellulose, are polymers of monosaccharides linked through the active groups. The chemical properties of saccharides vary depending upon the number of hydroxyl groups and the presence or absence of –CHO/= CO groups. These variations are the basis in the development of colour reactions to identify the saccharides. Some simple tests used to identify the presence/absence of certain saccharides are listed below:

Plants are exposed to various stresses such as temperature, water, oxygen, salts, nutrition etc, during its growth under dry land condition. Various simple tests have been developed by plant scientist for evaluation of different cultivars against these stresses. These tests are simple to perform in the laboratory with fewer instruments that are commonly available in most of the laboratories in developing countries. These tests have significance in plant water relations and cultivars reliably screened for various stresses. The crops upon which these tests have been performed here are used by the proponents of the tests. These tests are not advised to be performed on crops other than those used by the authors. It probably needs standardization for other crops. The following test has been explained for the benefit of the readers.

Hydroponics is a subset of hydroculture and is a method of growing plants using mineralnutrient solutions, in water, without soil. Terrestrial plants may be grown withtheir roots in the mineralnutrient solution only or in an inert medium, suchas perlite, gravel,mineral wool, expanded claypebbles or coconut husk

The techniques on hydroponics are widely used in plant sciences to elucidate several problemson nutrition. Primarily, this has been not only used to evaluate deficiency symptoms of an essential element but also used to assess waters stress effects in crop plants. There has been a considerable controversy whether such responses paralled with field responses. Though these techniques have their limitations, it is certain that it has its relevance in identifying certain genotypes relatively tolerant to some stresses such as water, O₂ and nutrition. Without entering to such debatable issue, it can be said thatwherenecessity demands, such techniques would proveuseful in demonstration purposes and evaluation of macronutrient deficiencies in tomato and maize. Thegrowing of plants in nutrient solution is called as water culture or hydroponics. These experiments in nutrient solutions are carried out to study the mineral nutrient relation of plants. By elements required for plant growth, specific deficiency symptoms can be produced in water culture experiments. Thesuccess of these experiments of producing deficiency symptoms depends upon the use of homogenous biological material and purity of culture solution in respect of different plant nutrients. Hydroponics is a subset of soilless culture. Many types of soilless culture do not use the mineral nutrient solutions required for hydroponics.

Plants that are not traditionally grown in a climate would be possible to grow usinga controlled environment systemlike hydroponics. NASA has also looked to utilize hydroponics in the space program. Ray Wheeler, plant physiologist at Kennedy Space Center’s Space Life Science Lab, believes thathydroponics will create advances within space travel. He terms this as a bioregenerative life support system.

Growth and Development are the most fundamental and conspicuous characteristics of all living organisms. According to dictionary, growth is the advancement towards maturity and development is a gradual increase in size. The plant physiological definition of growth is ‘an irreversible increase in mass, weight or volume of a living organism, organ or cell.

Tissue culture refers to the collection of techniques used to maintain or grow of cells, tissues and organs under controlled environment. The German botanist G. Haberlandt (1854-1945) originated the concept of cell culture in which he described his pioneering experiments with isolated plants cells and developed a concept of totipotency (potential of a cell to reproduce entire plant and all of its characteristics). He is considered as father of tissue culture.

Much of the success on modern agriculture dependson the availability of high quality seeds with good genetic potential and proven performance in germination, emergence, and vigorous Vegetative growth.

Seed: Seed is a fertilized mature ovule containing an embryonic axis (embryo), stored food material (endosperm) and a protective covering (seed coat or testa).

Seed structures: Living embryo, the most important part of seed, consists of two structures (i) embryonic axis and ( ii ) cotyledon(s). Theembryonic axis is composed of three parts namely

(i)radical (embryonic root), the hypocotyls (point of attachment of cotyledons) and (iii) plumule (theshootapex with the first true leaves). Thethree parts of embryonic axis are easy to identify in dicots, but in monocots (especially in the family Gramineae) their identification is difficult. In monocots, there is only one cotyledon, which is reduced and modifiedto form the scutellum. The basalsheath of cotyledon is elongated to take the shape of coleoptile,while in somecases (e.g., maize), the hypocotyls is modified to form mesocotyl. The base of hypocotyls sheathing the radical is termed as coleorhiza.

Seed development: Thereare manyvariations in the pattern of seeddevelopment when the entire plant kingdom is considered. However, the general processof This includes seed development is almost similar.

Growth and differentiation are regulated by a group of organic compounds known as growth regulators. These growth regulators regulate growth not only at the organ level but also in the plant as a whole. They can be broadly defined as organic compounds synthesized in one part of a plant transported to another where at very low concentration they cause a physiological response.

There are five major groups of growth regulators, namely, the Auxins, Gibberellins, Cytokinins, Ethylene andAbscisic acid. Endogenously synthesized growth regulators are often referred to as plant growth hormones. However, a number of synthetic compounds eliciting similar response as that of the growth hormones have been identified and extensively used. These synthetic hormones effectively substitute the endogenous hormones to understand the basic mechanisms of hormones and also for commercial use.

Photosynthesis is an important physiological process associated with plant growth and productivity. During the process of photosynthesis, the solar energy is trapped and converted into chemical potential which is later used for the reduction of CO₂ into carbohydrates. The powerful reductant, NADPH that is needed for carbon reduction is generated by the light driven reactions of the chloroplast lamellar system. Photosynthesis can be summarized as follows.