eChapters

Genetic Transfer and Mapping in Bacteria

Bacteria can transfer genetic material during conjugation

Hfr strains contain an f factor integrated into the bacterial chromosome

Conjugation experiments can be used to map genes along the E. coli chromosome

A detailed genetic map of the E. coli chromosome has been obtained from many conjugation studies

Bacteriophages can also transfer genetic material from one bacterial cell to another in the process of transduction

Cotransduction can be used to map genes that are within 2 minutes of each other

Bacteria can also transfer genetic material by transformation

Horizontal gene transfer is the transfer of genes among different species

Linkage and Crossing Over

Crossing over may produce recombinant phenotypes.

Bateson and Punnett discovered two traits that did not assort independently.

Morgan provided evidence for the linkage of several X-linked genes and proposed that crossing over between X chromosomes can occur.

A chi square analysis can be used to distinguish between linkage and independent assortment.

Creighton and McClintock correlated crossing over that produced new combinations of alleles with the exchange of homologous chromosomes.

Crossing over occasionally occurs during mitosis. Genetic Mapping in Plants and Animals

The frequency of recombination between two genes can be correlated with their map distance along a chromosome

Alfred Sturtevant used the frequency of crossing over in dihybrid crosses to produce the first genetic map.

Trihybrid crosses can be used to determine the order and distance between linked genes.

Interference can influence the number of double crossovers that occur in a short region.

Genetic Transfer and Mapping in Bacteria a

Bacteria can transfer genetic material during conjugation

Hfr strains contain an F factor integrated into the bacterial chromosome

Hfr strains can transfer a portion of the bacterial chromosome to recipient cells

Conjugation experiments can map genes along the E. coli chromosome

A genetic map of the E. coli chromosome has been obtained from many conjugation studies

Bacteria may contain different types of plasmids

Bacteriophages transfer genetic material from one bacterial cell to another via transduction

Cotransduction can be used to map genes that are within 2 minutes of each other

Bacteria can also transfer genetic material by transformation

Bacteria may acquire new genes by horizontal gene transfer

Sex Chromosomes

Sex can be considered at chromosomal, gonadal, phenotypic, and gender identity levels.

Human females are homogametic (XX) and males are heterogametic (XY).

The Y chromosome contains few identified genes, while the larger X chromosome contains several thousand genes. Pseudoautosomal regions at both tips of the Y chromosome contain genes that have counterparts on the X chromosome.

The male determining gene, SRY, has been found on the Y chromosome.

Portrait of a Chromosome

• Cytogenetics is the study of chromosome abnormalities and associated effects on health or other traits.
• Excess or deficient genetic material can cause syndromes or end prenatal development.
• Chromosomes consist of highly coiled DNA, RNA, histones, and nonhistone proteins.

Telomeres and Centromeres are Essential

Telomeres consist of repeat sequences and protect chromosome tips.

A centromere is a constricted site where spindle fibers attach during cell division.

Centromeres are regions of repeated DNA bound to centromere-associated proteins.

Variation in Chromosome Structure

Natural variation exists in chromosome structure

Changes in chromosome structure include deletions, duplications, inversions, and translocations

The loss of genetic material in a deletion tends to be detrimental to an organism

Duplications tend to be less harmful than deletions

Duplications provide additional material for gene evolution, sometimes leading to the formation of gene families

Copy number variation is relatively common among members of the same species

Comparative genomic hybridization is used to detect chromosome deletions and duplications

Inversions often occur without phenotypic consequences

Inversion heterozygotes may produce abnormal chromosomes due to crossing over

Translocations involve exchanges between different chromosomes

Individuals with reciprocal translocations may produce abnormal gametes due to the segregation of chromosomes

Identification of DNA as the Genetic Material

Experiments with pneumococcus suggested that DNA is the genetic material

Hershey and Chase provided evidence that the genetic material injected into the bacterial cytoplasm is T2 phage DNA

RNA functions as the genetic material in some viruses Work Before Watson and Crick

Nucleotides are the building blocks of nucleic acids

Nucleotides are linked together to form a strand

In 1869, Miescher first isolated DNA and named it “nuclein.”

In 1902, Archibald Garrod linked heredity to enzyme (protein) defects. In 1909 he published a book entitled “Inborn Errors of Metabolism.”

In 1928, Griffith identified a “transforming factor” that transmitted infectiousness in bacteria.

In 1944, Avery, MacLeod and McCarty showed that the transforming factor was DNA)

In 1950, Hershey and Chase, using their famous “blender” experiment, confirmed that DNA, not protein, is the genetic material.

The work of chemist Phoebus Levene showed that DNA includes deoxyribose, nitrogenous bases, and phosphates, in equal proportions.

Chargaff s data showed that the number of purines equals the number of pyrimidines.

Using Rosalind Franklin’s X-ray diffraction patterns, Watson and Crick deduced that DNA is a double helix

Overview of Transcription

Gene expression requires base sequences that perform different functional roles

The three stages of transcription are initiation, elongation, and termination

RNA transcripts have different functions Transcription in Bacteria

A promoter is a short sequence of DNA that is necessary to initiate transcription

Bacterial transcription is initiated when RNA polymerase holoenzyme binds at a promoter sequence

The RNA transcript is synthesized during the elongation stage

Transcription is terminated by either an RNA-binding protein or an intrinsic terminator

The Genetic Basis for Protein Synthesis

Archibald Garrod proposed that some genes code for the production of a single enzyme

Beadle and Tatum’s experiments with Neurospora led them to propose the one gene-one enzyme hypothesis

During translation, the genetic code within mRNA is used to make a polypeptide with a specific amino acid sequence

Exceptions to the genetic code are known to occur, which include the incorporation of selenocysteine and pyrrolysine into polypeptides

Synthetic RNA helped to decipher the genetic code

The use of RNA copolymers and the triplet binding assay also helped to crack the genetic code

A polypeptide chain has directionality from its amino terminal to its carboxyl terminal end

The amino acid sequences of polypeptides determine the structure and function of proteins

Cellular proteins are primarily responsible for the characteristics of living cells and an organism’s traits

The Structure of Proteins

Proteins are composed of building blocks called amino acids. A string of amino acids is called a polypeptide chain. Once such a chain has folded into its working three-dimensional shape, it is a protein. Though there are tens of thousands of different proteins, all of them are put together from a starting set of 20 amino acids. It is the order in which the amino acids are linked in a polypeptide chain that determines which protein will be produced.

General Effect of Mutation

Gene mutations are molecular changes in the DNA sequence of a gene

Gene mutations can alter the coding sequence within a gene

Gene mutations are also given names that describe how they affect the wild-type genotype and phenotype

Gene mutations can occur outside of the coding sequence and still influence gene expression

DNA sequences known as trinucleotide repeats may cause mutation

Changes in chromosome structure can affect the expression of a gene

Mutations can occur in germ line or somatic cells

Sister Chromatid Exchange and Homologous Recombination

The staining of harlequin chromosomes can reveal recombination between sister chromatids

The holliday model describes a molecular mechanism for the recombination process

More recent models have refined the molecular steps of homologous recombination

Various proteins are necessary to facilitate homologous recombination

Gene conversion may result from DNA gap repair synthesis or DNA mismatch repair

Recombinant DNA Technology

A transgenic organism contains foreign DNA.

Biotechnology is the industry dedicated to using altered cells or molecules for various applications.

Recombinant DNA technology (i.e. gene cloning) was the first of the modern biotechnologies.

Gene targeting uses precision techniques to “knockout” a gene or substitute a gene for one on a chromosome.

Bioethics questions, gene patenting, and potential uses and risks of biotechnology pose treat questions for society.

Uses of Microorganisms in Biotechnology

Somatostatin was the first human peptide hormone produced by recombinant bacteria

Many important medicines are produced by recombinant microorganisms

Bacterial species can be used as biological control agents

The release of recombinant microorganisms into the environment is sometimes controversial

Microorganisms can reduce environmental pollutants

Functional Genomics

• Expressed genes can be identified in a cDNA library
• A microarray can identify genes that are transcribed
• The coordinate regulation of many genes is revealed by a DNA microarray analysis

Proteomics

The proteome is much larger than the genome

2D gel electrophoresis is used to separate a mixture of cellular proteins

Mass spectrometry is used to identify proteins

Protein microarrays can be used to study protein expression and function

Genome Sequencing: A Continuation of Genetics

• The human genome project involves the assembly of a DNA sequence map for the 3 billion base pairs present in all 23 human chromosomes.
• Two groups, the International Consortium and Celera Genomics, used two opposite strategies to obtain a draft sequence of the human genome.
• The use of bacterial artificial chromosomes (BACs), shotgun clones, and positional cloning has yielded a detailed look at the human genome and is facilitating the identification of disease causing genes.

The Sanger Method of DNA Sequencing

The Sanger method of DNA sequencing involves an enzymatic extension reaction to generate complementary copies of an unknown DNA sequence.

Incorporation of “dideoxy” base causes chain termination and separation of extension products on polyacrylamide gels reveals the sequence bases in the unknown DNA.

DNA sequencing occurs on a vast scale today through the use of automated DNA sequencing machines.

Genetic Analysis of Diseases

A genetic basis for a human diseases may be suggested from a variety of observations

Inheritance patterns of human diseases may be determined via pedigree analysis

Many genetic disorders are heterogeneous

Genetic testing can identify many inherited human diseases

Prions are infectious particles that alter protein function posttranslationally

Invertebrate Development

The early stages of embryonic development determine the pattern of structures in the adult organism

The study of Drosophila mutants with disrupted development patterns has identified genes that control development

The generation of a body pattern depends on the positional information that each cell receives during development

The gene products of maternal effect genes are deposited asymmetrically into the oocyte and establish the anteroposterior and dorsoventral axes at a very early stage of development

Gap, pair-rule, and segment-polarity genes act sequentially to divide the Drosophila embryo into segments

The expression of homeotic genes controls the phenotypic characteristics of segments

The developmental fate of each cell in the nematode Caenorhabditis elegans is known

Heterochronic mutations disrupt the timing of developmental changes in C. elegans

Quantitative Traits

• Quantitative traits exhibit a continuum of phenotypic variation that may follow a normal distribution
• Statistical methods are used to evaluate a frequency distribution quantitatively
• Some statistical methods compare two variables with each other

Polygenic Inheritance

Polygenic inheritance and environmental factors create overlaps between genotypes and phenotypes

Polygenic inheritance explains DDT-resistance in Drosophila

Quantitative trait loci (QTLs) are now mapped by linkage to molecular markers

Genes in Populations

• A population is a group of interbreeding individuals who share a gene pool
• Some genes are monomorphic, and others are polymorphic
• Population genetics is concerned with allele and genotype frequencies

The Hardy-Weinberg Equilibrium

The Hardy-Weinberg equation can be used to calculate genotype frequencies based on allele frequencies

Nonrandom mating may occur in natural and human populations

Origin of Species

A biological species is a group of reproductively isolated individuals

Speciation usually occurs via a branching process called cladogenesis

Divergent evolution can be allopatric, parapatric, or sympatric

Müntzing was able to re-create an allotetraploid species

Evolution can proceed gradually or be punctuated by periods of rapid change

When Allele Frequencies Stay Constant

The Importance of Knowing Allele Frequencies

Population genetics concerns the study of allele frequencies in a population.

Genes in a population comprise the gene pool.

Gene flow is movement of alleles between populations.

Microevolution reflects changes in gene frequencies in populations, which can be traced using the Hardy-Weinberg equation.

Allele frequencies are affected by mutation, migration, genetic drift, selection, and non-random mating.

Definition and History

The dictionary meaning of property is ‘estate whether in lands, goods or money’; such property is often referred to as tangible, material or physical property. The laws of the land protect the ownership of and the associated rights to physical property. In contrast, “intellectual property is an idea, a design, an invention, a manuscript, etc. which can ultimately give rise to a useful product/ application. The development of such property, as a rule, requires intellectual inputs, ingenuity and innovativeness; it also demands considerable monetary and other resources. Therefore, inventor of an intellectual property would like to ensure at least a fair reward for copied, imitated or reproduced; this minimizes the returns to the original inventor. Intellectual property right recognizes the right of an inventor to derive economic benefits from his invention (i.e. intellectual property); this right is called intellectual property right (IPR), (Singh, 2002). The governments, however, recognize the IPR, only so long as it is not to the detriment of the society. In India, innovation and novel techniques were retained within the families / small social groups that developed them, and there was no other system of protecting their rights to the knowledge so generated. The brief history of intellectual property right in India is:

In 1856, the British Government in India introduced the Act of Protection of Inventions. This act was based on the British Patent Law of 1852.

In 1872, Patents and Designs Protection Act was passed.

In 1883, the Protection of Inventions Act was introduced. It was consolidated as Inventions and Designs Act in 1888.

On 15 August 1947, the Indian patents and designs came under the management of Controller of Patents and Designs.

The Indian Patent Act (1970) was introduced in the parliament in 1965, was modified in 1967 and passed in 1970.

Protection of designs is covered by the Indian Patent and Design Act (1911) with amendments in 1978 and amended rules in 1985.

Trademark protection is in force since 1 June 1948 under the 1940 Act. This act was amended as Indian Trade and Merchandise Marks Act (1958), which became effective on 25 November 1959.

The copyright laws in India are as per international standards.

Vegetables are rich source of nutrients, vitamins and minerals. Phytochemical contents in vegetables and their strong antioxidant potential in scavergering ree radicals have generated tremendous attention among the consumers. Consumption of vegetables has significant health-promoting effect and can reduce the incidence of cardiovascular diseases, cancer, Acquired Immuno Deficiency Syndrome (AIDS) and various other degenerative diseases. Human health, in recent years, has assumed an unprecedented status. The rising population levels, increase in mental stress and changes in dietary habits have resulted in various forms of degenerative diseases including cardiovascular, cancer and ageing. As a result, there has been an alarming explosion in consumers’ interest in health. In recent past, tremendous progress has been made for increasing vegetable production in the country. India has emerged as the second largest producer of vegetables next to China. During 2000-2001, India produced 93.92 million tonnes of vegetables from 6.24 million ha of land, accounting a productivity of 15.0 tonnes/ha. During 1991-1992, total vegetable production was 58.54 million tonnes from 5.59 million ha of land, with productivity of 10.5 tonnes/ha. Thus, in last one decade country has multiplied its vegetable production one-and-a-half times. Presently, India’s share is more than 13.60%. Our country will need to produce 215 million tonnes vegetables by 2015 to meet the demand of domestic and export markets. The increase in vegetable production by increasing area under vegetable cultivation is limited due to continued decrease of land holdings. Hence, it is essential to increase vegetable productivity to fulfill country’s requirements for food and nutritional security and poverty alleviation.

Genetic Basis of Heterosis

There are three theories to explain the genetic basis of heterosis: (1) dominance hypothesis, (2) over-dominance hypothesis and (3) epistasis.

Dominance Hypothesis

Davenport (1908) first proposed this hypothesis and he considered that heterosis is a consequence of action and interaction of favourable dominant genes brought together in a hybrid. Bruce, Keeble and Pellew explained it in 1910. This hypothesis suggests that at each locus the dominant allele have favourable effect, while recessive allele has unfavourable effect. In heterozygous state, deleterious effects of recessive alleles are masked by their dominant alleles. Thus, heterosis results from masking of harmful effects of recessive alleles by their dominant alleles. The harmful effects of recessive alleles, which becomes homozygous due to inbreeding. Therefore, according to dominance hypothesis, heterosis is not the result of heterozygosity; it is the result of prevention of expression of harmful recessive allele by their dominant alleles (Fig.1). In this hypothesis, there are two objections (i) the first objection relates to the failure in isolation of homozygous lines for all the dominant genes, and (ii) the second objection is directed at the symmetrical distribution in F₂. Both the objections are discussed below:

Basic Requirements

Hybrid seeds could be produced at cheap rates only if the crop species have certain built-in morphological or physiological mechanisms, suitable for the control of parentage for successful hybrid seed production and its floral morphology, is amenable to it. Some of the basic requirements and techniques employed in large-scale commercial hybrid seed production of crop plants are as follows:

• Availability of a proven heterotic hybrid combinations which could distinctly and profitably surpass the yield levels of commercial variety being grown.
• Availability of an easy, economic and effective means of eliminating or rendering functionless of male part of bisexual seed parent, mechanically, genetically or even biochemically.
• Availability of a strong fertility restoration system (in case of the use of cytoplasmically governed male sterility system) or availability of a tightly linked marker gene system in genetically governed male sterility along with full and detectable expression of self-incompatibility.
• Absence of modifier genes or gene systems in case of the use of self-incompatibility for hybrid seed production.
• Complete synchronization of flowering in both seed and pollen parents.
• Free, unrestricted and natural transfer of pollen from pollen to seed parents.
• Good seed setting on seed parent.
• A skilled organized effort for large-scale seed production, certification, processing and well-knitted distribution of hybrid seeds.

Reproduction

Since the life of an individual plant is limited in duration, it has developed certain mechanism by which it can reproduce itself inorder to continue the perpetuation of the species and also to multiply in number. Mode of reproduction determine the genetic constitution of crop plants, that is, whether the plants normally homozygous or heterozygous. A knowledge of the mode of reproduction of crop plants is also important for making artificial hybrids. The various modes of reproduction found in crop plants may be broadly grouped into the following two categories : (i) Asexual and (2) Sexual.

Asexual Reproduction

Heterosis breeding systems depend upon the reproduction system of plants, whether the plant is propagated asexually or sexually. Therefore, before development of hybrids, information regarding type of flower, flowering habits and floral biology is required in hybridization programme (emasculation and pollination). In a sexual reproduction, plants develop from vegetative parts of plants (vegetative propagation) or may develop from unfertilized gametes, ovular tissues, and modified cells (apomixes). Vegetative reproduction includes plant regeneration from underground stems such as tubers in potato, bulbs in onion and garlic, underground tubers such as sweet potato, corms in yams, and rhizomes in ginger and turmeric. In certain cases, aerial parts are used for propagation as stem cuttings in tapioca, sweet potato, watercress, and drumstick, root suckers in curry leaf and globe artichoke and turfts in chive. In apomixes, sexual reproduction or gamete fusion is replaced with other form of asexual reproduction. In this case, embryo develops without fertilization. Apomixis may be of different types: (1) Apogamy—where embryo develops from a gametic cell of embryo sac other than egg cell. Apogamy may be haploid or diploid. Diploid apogamy has been reported in onion. (2) Polyembryony—where more than one embryo develops from a seed, resulting in more than one seedling. In this case, embryos usually develop from nucellus integuments, or chalaza in addition to normal syngametic embryo. (3) Parthenogensis where embryo develops from an unfertilized egg. This may be at haploid or diploid level. Sometimes, embryo development take place from unfertilized egg of a diploid plant. This is called haploid parthenogenesis. It originates in plants due to environmental effects, especially due to effects of high or low temperature, use of foreign pollen, application of chemicals, and use of irradiated pollen. Haploids parthenogenesis produces haploids.

Concept

Basic concept of this type of improvement is to accumulate, infuse and improve the frequency of favourable genes in established population. This includes the removal or substitution of an undesirable gene with a counterpart favourable one with the superior performance in a given environment, incorporation of a balanced gene combination for better performance - per se or may be even bringing in a better plant type congenial for better physiological activity and biochemical versatility, resulting in better performance of a population. As per theory of Hayes (1963), most of the commercial varieties/hybrids can be improved in one way or the other for one or more of the agronomic attributes. This is primarily because some of the lines in each hybrid generally excel in comparison with other in their ability to transmit desirable characters to their hybrid progeny and thus provide scope for the improvement of the weak inbred lines of the hybrid to further better its performance. The choice of the particular population improvement technique mainly depends upon the genetic information. Since by and large, population improvement techniques envisage controlled crossing followed by selection and recrossing by further selection. This information is vital. Therefore, before deciding upon the choice of a particular methodology, such information as the type of gene action involved in the expression of attribute under improvement, nature of genetic associations, extent of heritability, various possibilities of genetic manipulations should be available. Some of the procedures, which could be successfully utilized in population improvement of parents used in released hybrid populations, are backcross method of breeding, convergent improvement, gamete selection, technique for the removal of complementary genes and step ladder method of breeding.

Hybrids are released for commercial cultivation either by the Central or State Varieties Release Committee. The release of a hybrid for commercial cultivation is based on conclusive demonstration of its superiority over the best existing hybrids (included as check in evaluation trials) in yielding ability or in some other features of economic importance, e.g. abiotic and biotic stresses etc. Due to above reason, hybrids are extensively evaluated for their performance, resistance to diseases and insects, and quality in multilocational trials. The multilocational trials are conducted under All India Coordinated Vegetable Improvement Projects, which play a key role in testing, identification and release of new hybrids. Before release of hybrids, three activities and operations are involved. These are:

Meaning and Importance

Genetic purity denotes the percentage of seeds (by weight) belonging to the variety/hybrid under certification. It is one of the primary criteria of seed quality. The efforts of plant breeders become fruitful only when sufficient quantities of good quality seeds of improved varieties/hybrids reach farmers / growers. This is necessary to take all round care at every step of seed multiplication before the seed is delivered for marketing. Hence, genetic purity testing is of critical importance not only to farmers but also to plant breeders, seed producers as well as quality control enforcing agencies. Increasing emphasis on hybrid cultivars due to their better performance and quality produce, more money and expertise have been put in further research of hybrid development. In this context, protection of parental lines is assuming critical importance and for that purpose, several breeding institutes do adopt various strategies for identification, characterization and protection of their parental lines as to avoid pilferage and misuse of their proprietary lines by other organizations. Use of random amplified polymorphic DNA (RAPD) and other molecular markers for evaluating seed purity of F₁ hybrids and their parental lines are closely related, thus, helps in assessing contamination of F₁ seeds even with the seeds of sib (inbred seed and seed from self-pollination of parental lines). For genetic purity testing of hybrids seeds, it is imperative that parental lines of hybrid be adequately characterized on the basis of maximum number of distinguishable descriptors (morphological, biochemical or molecular markers).

Origin, History and Definition

The term biotechnology was coined by Karl Ereky, a Hungarain engineer, in 1919. The origin of biotechnology can be traced back to prehistoric time when armers and gardeners have been making use of hybridization and grafting among plants with a view to bring about an improvement in existing attributes. Using these approaches, several hundred varieties in ornamental plants were produced. Microorganisms were already used for processes like fermentation, formation of yoghurt and cheese from milk, vinegar from molasses, production of butanol and acetone from starch by Clostridium acetobutylicum or the production of antibiotics like penicillin from Penicillium notatum. Four defferent phases of biotechnological research were witnessed during the last century. In 1920, Chain Weizmann used Clostridium acetobutylicum to convert starch into butanol and acetone (during world war I, acetone was used as an essential component of explosives). Alexander Fleming in 1929 discovered penicillin from Penicillium notatum and wounded soldiers were given treatment using this antibiotic during world was II. In 1970s with the discovery of restriction enzymes, which led to the development of recombinant DNA, technology brought a revolution in the field of biology. The latest phase in the history of biotechnology is the study of structure and function of whole genome (DNA) and whole proteome (protein). This area of research is described as genomics and proteomics, respectively. Some more important activities in the field of biotechnology are given in Table1

In fact, biotechnology is the product of interaction between science of biology and technology. It is the technological exploitation and control of biological system. Biotechnology has wide range of its uses and accordingly Office of Technology Assessment described biotechnology as: (i) old biotechnology that includes fermentation, i.e. formation of vinegar from molasses and that of cheese and yoghurt from milk, production of antibiotics from certain fungi and process of baking and brewing and (ii) new biotechnology that includes the techniques of recombinant DNA and PCR polymerase chain reaction, cell culture and fusion and bioprocessing which became possible only through the researches in molecular biology. However, no efforts have been made to distinguish between old and new biotechnology. Keeping in view the importance of biotechnology, attempts have been made to define it. Following are some of the definitions of biotechnology, however, none of the definitions of biotechnology seems to be complete. The first definition seems to be comprehensive and wide.

Introduction

Hybrid is the first generation cross-produced through crossing between two genetically different plants, lines or varieties. The seeds produced in this way are called hybrid vigour, which serves as a key for increasing the yield of many self, and cross-fertilized crops. With limited possibilities of horizontal expansion in area and to meet the ever-increasing demand of quality vegetables by growing populations, the exploitation of hybrid vigour is best option for increasing both productivity and quality. Vegetable hybrids under optimum crop production and protection management produce economically more yield than improved, open-pollinated varieties. The uniform size, early maturity, improved nutritional quality, adaptability to adverse environments and resistance to various biotic and abiotic stresses, are additional advantages of hybrids resulting in better monetary returns to growers. Development of hybrids in vegetables brought about a near revolution but still India has not been able to harvest full potential of hybrid technology as compared to USA, Japan, Canada, Europe and Israel. About 10-12% of the total vegetable area is under hybrids in India as against 75-90% in Japan or USA. In India, only tomato and cabbage are leading vegetable crops, occupying 30-35% area under hybrids while rest of the vegetables cover less than 15%. The hybrid seed production and their cultivation, therefore, should be popularized on warfooting to achieve the targets. Many hybrids have been developed both by public and private organizations as given in Chapters 6 of Table 6, which are competing among themselves to produce best hybrids to compete in world market and selling seeds on very high rates ranging from Rs 5,000 to 50,000/ kg of seed. Though, they are making very huge profits but their contribution in promotion of hybrid technology is exemplary and cannot be overlooked.

Tomato

Genetic Resources

Tomato, a warm season crop, sensitive to frost, is usually cultivated in sub-tropical and mild cold climates. The National Bureau of Plant Genetic Resources (NBPGR), New Delhi, is the main centre for maintenance of tomato germplasms in India. The Bureau has systematically assembled more than 2,900 germplasms. Some of the promising germplasms identified for different traits on the basis of their morphological variations (Fig.1; see Plate-1) are given in Table1.

Okra

Genetic Resources

Okra [Abelmoschus esculentus (L) Monch.] s a crop of the tropical and subtropical owland regions of Africa, Asia, America and warmer temperate region of the Mediterranean. It is believed to be originated from tropical Asia or may have been existing in Africa and India as polyphylatic species. A. tuberculatus, one of the ancestors of okra occuring in India, has nine wild taxa, of which A. esculentus is popularly grown for pod production. The main region of cultivation and diversity of okra in India, Sri Lanka, Pakistan, Nepal and Bangladesh, are represented by various local cultivars of A. esculentus and A. moschatus (Table1).

Cabbage

Genetic Resources

Historical evidences indicates that modern hard-headed cabbage cultivars are descended from wild non-heading Brassica originating in the Eastern Mediterranean and in Asia Minor. The ancient Greeks held these early forms of cabbage in high regard and believed that they were a gift from the God. The Clelts and, the Romans disseminated cabbage throughout Europe. In fact, the Latin name Brassica is derived from the Celtic word bresi meaning cabbage. Over a period of centuries, hard-headed cabbage types evolved in northern Europe, while loose-heading, heat resistant types developed further in South. Cabbage was first introduced USA when the French explorer Jacques Cartier planted seed in Canada on his voyage in 1541. Cabbage is grown for the thickened main bud called head. The Portuguese introduced cabbage much earlier than cauliflower. There are reports that it was also grown during the Mughal period. In India, much varieties of cabbage are not available. However, genetic resources of cabbage for high yield and resistance to biotic stress are given in Table1.

Bitter Gourd

Genetic Resources

Bitter gourd or balsam pear (Momordica charantia L.) is one of the most popular cucurbitaceous vegetable, commonly cultivated in many countries. Probably, India is the centre of origin and secondary centre of diversity of this crop. Bitter gourd is an annual monoecious herb, belongs to the genus Momordica that comprises 60 species. Out of these, only M. charantia, M. cochinchinensis, M. dioica, M. balsamina (balsam apple), M. cymbalaria (syn. M. tuberosa) are under cultivation. Momordica charantia is grown all over the country in tropical and subtropical climates and rich genetic diversity occurs in northern plains including tarai region, the northern-western plains, the central region/plateau and the western and eastern peninsular regions. Kakrol (M. dioica) is cultivated in West Bengal, Assam, parts of Bihar, while sweet gourd (M. cochinchinensis) is popular particularly in Tripura, Assam, Andaman Nicobar, Tamil Nadu, Uttar Pradesh, Bihar and West Bengal. M. denundata (Thw) Clarke (syn. M. dioica var. denundatais) is found abundantly in Kerala, M. macrophylla in Assam and M. sabangulata Blume is commonly found in Karnataka, Maharashtra, Meghalaya and Sikkim. In India, NBPGR , New Delhi, and IIVR, Varanasi, are actively engaged in the collection of bitter gourd germplasms.The NBPGR, New Delhi, has evaluated 33 collections for 37 characteristics. Variability has been reported in vine length (105-335 cm), number of primary branches (3-7), number of fruits/plant (1-25), fruit girth (8-27 cm), fruit length (9.5-20 cm) and fruit yield/plant (0.5-2.8 kg). Accessions, UB-22, UB-66, IC-74158, C-1621 and K-3374, have been found better yielder. At IIVR, Varanasi, 121 genotypes have been evaluated for yield and yield-contributing traits. VRB-40 & IC-44415A have been identified as promising lines. Accessions showing better charecters for different traits are given below (Ghosh and Kalloo, 2000):

Carrot

Genetic Resources

Wild carrot (Queen Anne’s Lace) grows in emperate region around the world but the extent of genetic variability in wild population has not yet been evaluated in Daucus carota or related species. Constance (1971), Heywood (1983) and Mathias (1971) have contributed much to our understanding of Umbelliferae systematics, but relatively little carrot germplasm has been collected for distribution. The cultivated carrot, Daucus carota L, intercrosses freely with almost all the wild forms. Although, no incompatibility has been observed but protandry is the main reason for cross-pollination. However, there is no barrier for selfing. Carrot variety Brasilia is resistant to nematode, Meloidogyne incognita, while species Daucus carota subsp. hispanicus has resistance to other nematode, M. hapla (Simon, 1993). The genetic material, resistant to disease and pest of carrot, which can be used for developing hybrids for abiotic stresses, are given in Table1.

Onion

Genetic Resources

In onion, much variation exists in bulb characteristics for size, shape, colour of skin and flesh, number of hearts, skin retention, firmness, pungency, TSS, yield etc. Bulbs may be white, red, brown or yellow, round, globe, flat or spindle shaped. Diversity is also found in field tolerance to Stemphyllium blight, purple blotch, basal rot and thrips. Various workers have also reported tolerance to soil salinity, reduced bolting, keeping quality and high dry matter content. In India, NBPGR, New Delhi, is a nodal agency engaged in collection, evaluation and maintenance of onion germplasms both from indigenous and exotic collections. Accessions numbering more than 1,000 onion germplasm lines are being maintained at NBPGR, New Delhi. Other centres maintaining sizeable number of germplasms are IIHR, Bangalore, Mahatma Phule Krishi Vidyapeeth, Rahuri, NHRDF also NRC on Onion and Garlic, Nasik; IARI, New Delhi, PAU, Ludhiana and IIVR, Varanasi. Indigenous collections account for more than 95% of the germplasm lines maintained in onion, which indicates the existence of large amount of variability within the country for short-day onions. However, it also indicates the necessity to enrich the existing germplasm pool by importing more exotic collections. Promising germplasms for different attributes are given in Table1.

Tomato

Tomato, a warm season vegetable, requires a long season to produce a profitable crop. The optimum range of temperature for its cultivation should be 21–24ºC. The mean temperatures below 16ºC and above 27ºC are not desirable. The minimum, optimum and maximum soil temperatures for seed germination are 10º, 30º and 35ºC, respectively. Maximum seed germination occurs at 24ºC. Maximum fruit setting occurs at night temperature of 15-20ºC. Flowers fail to set fruit below 13ºC and beyond 38ºC. Formation of red colour due to lycopene is inhibited when temperature exceeds 32ºC. Lycopene is highest at 21-24ºC, while its production drops off rapidly above 27ºC. Tomato plants are highly susceptible to high rainfall areas if proper drainage is not available.

It is grown in many types of soil from sandy to heavy clay. A well-drained fairly fertile loam soil with a fair moisture-holding capacity is ideal for growing its good crop. It prefers a soil having a pH of 6.0 - 7.0. Application of liming is beneficial if it is cultivated in acid soils.

It can be grown almost round the year. The planting seasons vary from place to place. In northern India, for spring summer crop, it is sown in November and transplanted in second fortnight of January. In area, where frost does occur, it is sown in July-August and transplanted in August-September. In hilly areas, it is sown in March-April and transplanted in April-May.

INTRODUCTION

Bangladesh is a very small country of 1,47,570 square kilometer area having a population of 150 millions. The country has only 8.29 million hectare (Bangladesh Krishi Diary, 2003) cultivable land against the huge population. The land area is gradually decreasing because of population growth, industrialization and other infrastructure development. This results in a declining trend of per capita land availability from 0.13 hectare to 0.06 hectare during the last few decades (1960 to 2000) (Food and Agriculture Organisation, Bangladesh Country Profile).

In order to ensure food security of this vast population and with the emergence of “Green Revolution” in 1960s, priority was given to produce more food in terms of grain through intensification of land usage. New crop variety (HYV), chemical fertilizers, pesticides and irrigation were introduced. As a result, immediate objective of more grain (rice) production had increased and Bangladesh had temporarily achieved self sufficiency in food (rice). Bangladesh made steady progress in crop agriculture in the post-independent period. Cropping intensity increased from 148 to 179 per cent and food grain production almost doubled during the period from 1969/70 to 1992/93 (Hoque, 2007).

However, a lot of HYVs, hybrids, which were introduced, required increased amount of chemicals, and over time they took a toll on the fertility of soil, gradually decreasing acreage production despite usage of high doses of chemical fertilizer and pesticides. Moreover, the natural disasters such as floods, droughts, etc., continued to result in fluctuation in production. Wide fluctuations in production led to large instability in food grain prices having serious implications for household food security and the welfare of the people. The attainment of food security and rural economic development, therefore, could no longer rely on the production of rice alone.

1. INTRODUCTION

There are many countries surrounded by the waters of the Caribbean Sea. These countries vary widely in size, topography, ethnicity, language spoken, agricultural production systems, main sources of income, income levels and styles of governance, to name a few.

This analysis covers only the countries where English is spoken as the first language. These countries are linked through a grouping of Caribbean Communities, called CARICOM, an organization of 15 Caribbean nations and their dependencies. It starts with Jamaica in the North to Trinidad and Tobago in the South, but also includes Belize in Central America and Guyana and Suriname in South America. Although French speaking Haiti and Dutch speaking Suriname belong to CARICOM, they are not discussed because of the language barrier. The other French speaking islands (Guadeloupe and Martinique) and the Spanish speaking islands (mainly the Dominican Republic, Cuba and Puerto Rico) have different administrations for agricultural development. CARICOM countries stretching from the tip of Florida, USA, in the North to Venezuela in South America. CARICOM includes Belize in Central America and Guyana and Suriname in South America.

INTRODUCTION

Nowadays, any issue related to “information and communication technologies in agriculture (ICTs)” is extremely interesting and it belongs to the modern subject-matters of the agricultural economics science. Unambiguously the above phrase is the buzz remark for the agricultural extension scientists considering that the process of communication is fundamental to extension, training and passing on information. Thus, learning processes, dissemination of innovations and social change cannot be explained without reference to communication (Albrecht et al., 1989).

An efficient communication strategy, especially when combined with a wide range of available ICTs, utilises the advantages of both personal and impersonal media communication. This can be achieved by building up, promoting and using communication networks and modern technologies. Under the term “network” we understand the complex of communication channels which ensure that all members of the target group receive the message more than once, both from various personal contacts and media. This calls for the use of existing communication relationships, the dissemination of information by multipliers and influential individuals and a range of media which are appropriate to the type of information and for reaching the target groups. As well thought out, communicative approach can partly compensate for the often lamented shortage of advisers provided that one is in a position to communicate a message in various ways, to evaluate feedback and then to take action accordingly.

1. INTRODUCTION

1.1. National Agriculture Scenario

Agriculture is the most important sector of Indian Economy, contributes 23 per cent of national GDP, accounts for 11 per cent of exports, and 50 per cent of billion depends on it. Interestingly India feeds 16 per cent of population with 2.4 per cent of global land.

In the last five decades, there has been a steady and spectacular transformation of Indian agriculture from the food deficit to food sufficient status. Diffusion and adoption of modern technologies, high yielding varieties, dedicated efforts of farmers, extension personnel and scientists and also programmatic support of central and state governments have all contributed significantly from 50 million tonnes in 1950-51 to land mark achievement of 230.67 million tonnes of food production in 2008-09.

1. INTRODUCTION

The agricultural paradigm in the developing world including Iran will have to be recast to take advantage of knowledge availability to achieve multiple goals of income, food, jobs, etc. Although, many farming communities in developing countries need timely expert advices to make them more productive and competitive, they are still facing a multitude of problems to maximize agricultural productivity. In spite of successful and promising researches conducted on new agricultural practices, majority of the farmers are not getting upper-bound yield due to several reasons. One of them is that scientific agricultural advice is not reaching the farming community in a timely manner. A wide information gap exists between research and practice.

To cope with this problem different countries have taken various measures. What is common in the extension systems of developing countries is that in a backdrop of rapid organizational and social changes in agriculture, new hardware and software devices have to be applied for better responsiveness to increasing farmers demand for timely and accurate information. At the pace of recent progress in ICT, within a decade it will be possible to provide instantaneous connectivity to millions of people, enabling mass customization and personalized services (Reddy and Ankaiah, 2005). Data mining technology can be used to extract useful knowledge from huge database and simulation technology can be used to predict in to the future (Wiederhold, 2002).

1. INTRODUCTION

There is increasing recognition that information and knowledge are now at the heart of socio-economic development. Information and Communication Technology (ICT) and broadband are enabling tools and infrastructures for accessing, developing, using and sharing information and knowledge. Accordingly, Irish Government policy has focused on promoting the adoption and use of ICT in the home, in education and in the workplace.

There have been significant increases in levels of engagement with ICT in Ireland in recent years. Almost two-thirds of all adults now have access to the internet, compared with only 1 in 20 in 1996, while four out of every five adults own a mobile phone. This chapter critiques the level of adoption of ICTs among the farming community and compares this with levels of adoption by the general population. It analyses the use of ICTs by the government and by public and private extension agencies in Ireland and identifies constraints to their adoption.

The Ministry of Agriculture has been among the most enthusiastic supporters of the Government of Ireland’s policy by promoting the adoption and use of ICTs among its clients. It sought to facilitate easier transmission of information to clients, to minimise the collection of new data by using existing electronic information and to integrate with clients’ own systems. These projects are described in this chapter.

The use of ICTs by the public extension system is also critiqued; it has been innovative in using ICTs to disseminate information to its clients and the use of mobile telephony has been particularly effective. Internet based services to deliver online training and advisory information have also been developed and are critiqued.

1. INTRODUCTION

The contribution of Extension and research to Israel’s agricultural productivity and profitability is a collaborative effort with research hailing back to the late 19^th century. It facilitated technological innovation in agriculture, transfer of information, training of farmers and connectivity. These were in effect a dictate of continuously deteriorating agricultural terms of trade, crippling water shortages and severe climate and soil constraints.

The Israeli Extension Service’s (IES) adoption of Information and Communication Technologies (ICTs) significantly enhanced extension’s capabilities and scope of activities. ICT empowered extension’s ability to develop, introduce and adopt innovative agricultural technologies and collaborate with research and other partners. Adoption of ICT as one of the tools of technological innovation dramatically improved the transfer and management of information, production chain efficiencies and integration within and with the agricultural sector. These were and are critical success factors contributing to Israeli Extension, Research, Services and Farmers ability to sustain a profitable and thriving agriculture sector. As such the overall results are a major contribution to rural viability and an illuminating case study of technological innovation adoption.

1. OVERVIEW OF AGRICULTURAL SCENARIO AND EXTENSION SYSTEMS IN JAPAN

1.1. Japanese Agricultural Policy and its Short History

The modernization of Japan’s agriculture was started through mechanization such as cultivators, rice planting machines, tractors and combines in the 1960s. Mechanization led to a large decrease in hours spent on rice cultivation, and the redundant labor force moved from agriculture to the manufacturing industry. This movement resulted in the modernization of rice cultivation, high productivity and high income for farm households.

On the other hand, a decreased demand for rice caused by westernization of the diet, e.g. greater consumption of animal products, became a serious problem. The national government decided to regulate rice production, and the acreage of paddy fields equivalent to the excess rice production has been used to cultivate other plants since 1978. Nowadays, the permitted area for planting rice is about 60 per cent of the paddy fields, with the other 40 per cent used to cultivate other plants such as barley, soybean, buckwheat and so on.

1. GENERAL INTRODUCTION

Agriculture, as one of the most important economic sectors in Jordan, is under increasing pressure due to rising population, consumer affluence, pressure from globalization and a shrinking resource base. Previous production challenges in Jordan have been met largely through improvements in traditional agricultural inputs such as seeds and agrochemicals, but the present challenges need different solutions. Better management, which involves higher degrees of information and knowledge, is widely seen as a way to address these challenges. The potentials that ICT has to offer range from the sharing and re-use of data, research findings, lessons learned and best practices among R&D institutions to developing quick response mechanisms for agricultural and natural resources crises situations; from permitting informed decision making among the agricultural officials to sounder policy making among the legislators; from improving the extension delivery systems in the rural areas to bringing e-Commerce to the farmers.

Agricultural extension is about the application of information into knowledge and adoption, such as application of scientific research to agricultural practices through farmer training. ICT broadly defined as facilitation by electronic means the creation, storage, management and dissemination of information. Two types of ICT – old and new are practiced in extension service; the former refers to radio and TV which are low cost and require little skill to use while the latter forms of ICT include networked computers, satellite-sourced communication, wireless technology and the internet. Assume key factors explaining different ICT taken up by country are: per capita income; levels of education; the rural concentration; and dispersal of a country’s population.

The development of ICT in Jordan is fast and the Jordan’s IT capacity related to agro-information dissemination needs to be vastly improved at the local level to allow the effective horizontal transmission of information and communication between the farmers and institutions. However, technological challenges have still to be addressed such as the lack of trained communicators, poor ICT infrastructures high costs and limited access to ICTs and lack of relevant content.

1. INTRODUCTION

In the past, conventional ICTs that have been applied to agricultural extension services include the use of television, radio, etc., and these media have been criticized as archetypical, passive, top-down in nature; hence they have not created meaningful impact on agricultural information delivery (Akpabio, 2007). As a result of this, extension roles have undergone several transformation, over the years. One of the objectives of agricultural extension is to create conducive platform for empowerment so that food security can be guaranteed. In order to guarantee food security there is need to utilize faster and more efficient techniques of project identification, selection, implementation and evaluation in the agricultural extension process (Braimoh and Oladele, 2000). The inadequacies of interpersonal communication strategy in development gave credence to the use of media support in development process (Yahaya, 2000). In recent times, further improvements have been made on the use of media support through digital media. This is what makes contemporary ICT more relevant.

Modern ICTs emerged in Nigeria at a time when there was need for change in the agricultural extension delivery system to suit the contemporary situation. The conventional forms of communication used by extension agents include written (bulletin, leaflets, newspapers, articles, personal letters, circular, etc.); spoken (general meeting, special meeting, farm and home visit, official calls, telephone calls and radio); visual (result demonstration, exhibits, posters, motion pictures, charts, slide) and spoken/visual (method demonstration meeting, result demonstration meeting, meeting involving motion pictures, meeting involving charts).Torimiro et al.,(2000) noted the non-usage of telephone calls in extension work, giving reasons as preference for the locally accessible and affordable forms of communication they can employ.

1. AN OVERVIEW OF RWANDA’S SOCIO-ECONOMIC SETTING

Rwanda is a small landlocked country located in East Africa covering a total surface area of 26,338 km². It lies about 120 km south of the Equator and is bordered by Uganda in the North, Tanzania in the east, Burundi in the south and the Democratic Republic of Congo in the West. According to the national official statistics, the total population is approximately 8,200,000 people, with women accounting for 55 per cent of the people. The country’s population density is 505 people per km², making it one of the most densely populated countries in Africa (National Institute of Statistics, 2002). Since the turn of the millennium, the annual growth rate of the population has been 2.9 per cent and it is believed that by the year 2020, the country will have an estimated population of 20 million, thus exerting pressure on the limited land resources. It is also important to note that most people (64 per cent), those living in abject poverty, reside in rural areas of the country (Government of Rwanda, 2008).