Lec 03 – Apomixis – classification and significance in plant breeding. 2. 8. 4. Increase in number of floral parts but poor flowering. 2. 10. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. Exchange of purine base by purine base or pyrimidine by pyrimidine base in a DNA segment or cistron is known as transition. By the use of plant breeding, yields increase to a large amount. Collection of genetic variability or germplasm. It is an essential pre-requisite in the field of plant biotechnology. (iv) Bagging, tagging and labeling of males as well as females to be used in crosses, is done. Phenotypic changes which are produced by gene mutation are reversible, whereas due to structural and numerical changes in chromosome are irreversible. Autotriploids are highly sterile because of the random segregation of three chromosomes of each trivalent produced. Allopolyploid cultivated plants include wheat, sugarcane, cotton, tobacco and sesame. Heterosis (Hybrid Vigour) and Inbreeding Depression: Achievements and Limitations of Mutation Breeding: Role of Autopolyploid in Plant Improvement: Role of Allopolyploids in Plant Improvement: 10. Before performing hybridisation, a plant breeder should have all the information about the time of flowering, the time when the anther and. Growing these hybrids in the research fields and recording their performance under ideal fertilizer application, irrigation, and other crop management practices are essential. To ensure availability of pure seed of different crops to farmers, elaborate seed programmes (production and distribution) exist in most of the countries. Traditional farming yields less biomass in a considerable amount of time. Plant breeding is the purposeful manipulation of plant species to create desirable plant types that adapt to human needs more efficiently. The F 1 hybrid seeds are then planted to produce the commercial crop. e. Introduction of plants from one state of a country to another state of the same country is called interstate plant introduction. (ii) The mutation rate is extremely low and a very large number of plants must be screened to identify the few individuals that may have desirable mutations. This is the very first step aimed at increasing food production. Different wild varieties, species of wild types are a pre-requisite for effective exploitation. Domestication is the process of growing plants and keeping animals under human care and management. 1. 3. The entire collection of the diverse alleles of a gene in a crop is called the germplasm collection. Welcome to BiologyDiscussion! 2. the genetic characteristics of a crop. (ii) Forest Research Institute, Dehradun. Since triploids are sterile, triploidy is used in such cases for developing seedless varieties. Inbred line: It is a relatively true-breeding strain resulting from at least 3 successive generations of controlled self-fertilization or back crossing. This manipulation involves either controlled pollination, genetic engineering, or both. 1. You are a Botanist, working in the area of plant breeding. 3. Describe the various steps that you will undertake to release a new variety. It is the process of introducing plants or germplasms either from a foreign country or introducing plants or germplasm from one region to other regions of the same country. All the seeds are mixed in a single lot and therefore, the method is known as mass selection. 4. 6. Seeds are maintained separately and sown in the coming season to raise F1 generation. 2. stigma are ready for pollination, how long do the pollen grains remain viable, etc. In the early 1950’s Skoog and Miller showed that shoot or roots can be induced in the callus (organogenesis) by an appropriate balance of amounts of cytokinin and auxin in the medium. a. (iii) The stability of a mutant must be thoroughly tested as some mutants have a tendency to revert. Vegetatively reproducing crop plants are best suited for maintaining hybrid vigour because once a desired hybrid has been produced there are fewer changes of losing it. A number of crop varieties have been developed through mutation breeding. Many crop plants are propagated vegetatively even though they can bear seed. Thus for meeting the increasing demand of a growing population, it becomes necessary to increase the yield. To shortern the period for development of new varieties of plants. 4. This method is practiced in vegetatively propagated crops such as banana, potato, onion, citrus, etc. Unlike mass selection, here the progeny consists of a uniform population. Plant biotechnology is a set of techniques used to adapt plants for intentional usage and benefits. Pure line lacks variability. It is also known as chromosomal aberration. Reversal in order of genes in a part of chromosome. c. Thus, a breeder by pure line selection renders a particular type, more or less homozygous. The four steps are: (1) Creation of genetic variation by various means (2) Selection (3) Evaluation and Release as a variety and (4) Seed multiplication and distribution among farmers. The mutation rate depends upon the position and nature of the genes. The released varieties of Triticale are hexaploid (2n = 42) and have been synthesized by doubling the chromosome complements of sterile hybrids between T. turgidum (durum wheat, 2n = 28) and S. cereale (rye, 2n = 14). When two genotypically different plants are crossed, the genes from both the parents are brought together in F1 generation. On the other hand, hybridization between unrelated strains generally results in increased vigour and fertility—a phenomenon called hybrid vigour or heterosis. Video Lecture on Steps in Plant Breeding from Enhancement in Food Production chapter of Biology Class 12 for HSC, CBSE & NEET. Selection is again made from the progenies arising from the seeds of a single individual. If a single base ‘G’ is inserted in between G and U of first codon then a new protein will be produced. The objective of genetic engineering or recombinant DNA technology is to introduce one or more genes into an organism that normally does not possess them. Alpha particles, Beta particles, Fast and Thermal neutrons). So by continued backcrossing, canes with high sugar content have been obtained. Protoplast fusion or somatic hybridization. Euploidy has been used in plant breeding and improvement work. (iv) Some universities, gardens and agricultural departments also play an important role in introducing plants. This would require maintenance of seeds of superior varieties in genetically pure state, which would be multiplied every year to supply new seed to the farmers. Autoploids are characterized by the presence of same characters as the diploid parent, except that they are the large replica of the diploid parent. Methionine – Valine – Serine – Arginine – Valine – Leucine – Leucine. The latest interest in crop improvement is not to involve whole genome (as in conventional plant breeding or in protoplast fusion). It is also known as intra-generic hybridisation (within the same genus). 1. The degree of variation produced in the segregating generations would, therefore, depend on the number of heterozygous genes in the F1. Genetic transformation is also possible through co-cultivation (incubating recipient protoplast with purified DNA), electroporation (by applying high electric potential for a few micro-seconds to change the porosity of protoplast to take up DNA) and by micro-injection of DNA into the cell by fine needles. Seeds of improved varieties must be multiplied at a large scale in order to make them available to farmers for large scale cultivation. c. Introduction of plants from a foreign country is called intercontinental plant introduction. Chromosomes from different genomes do pair to some extent and multivalent are formed. The change of nitrogenous base sequence in DNA or gene is known as Gene or Point mutation. In allopolyploids, there is a cross between two diploids of different genomes, as in inter­specific hybridization. 2. The EU Commission has included the revision of a Community Plant Variety Right (CPVR) regulation in its recently published IP Action Plan, in a move welcomed by plant breeding organizations. Thus to maintain optimum heterosis, seeds must be produced every year by crossing the pure parental lines, which are constantly maintained. Increase tolerance to insect pest. Lately, the tissue culture technology has played a very crucial role in crops improvement programme. Such desirable sports occurring in well-adapted, asexually reproducing plants may result in quick improvements such as the colour sports in many apple varieties and superior shrub types in coffee plants. (iii) For studying the origin, distribution, classification and evolution of the plants. 1. The primary objective of plant breeding is to develop superior varieties of crops. It is an essential pre-requisite in the field of plant biotechnology. a. Germplasm is the sum of all the genes present in a crop, and it includes. Some of the important limitations of the use of mutation breeding for crop improvement are: (i) Most induced mutations are undesirable and have no value to the breeder. This process is repeated for a number of generations. Increase in cell size with more prominent nuclei. Hormones and mixtures of substances such as yeast extract, coconut water, bean seed extract are included in the medium by some workers. The various methods of artificial selection are: It is practiced in those plants which are cross-pollinated like Zea, Brassica. Then, the seeds of these selected plants are obtained. All introductions are subjected to quarantine, i.e., they are examined for the presence of insects, weeds and disease-causing organisms, and only those introductions that are free from the above are allowed to enter a country. "All vertebrates are chordates but all chordates are not vertebrates". F1 hybrids of maize have shown 30 to 50 per cent higher yields than those of the original open-pollinated cultivars from which the inbred lines were derived. 9. Our mission is to provide an online platform to help students to share notes in Biology. The cultured parts (termed explants) require a source of energy (usually sucrose), salts, providing macro-and microelements, a few vitamins and generally the amino acid, glycine, in the nutrient medium. Many induced mutations are lethal. 1. In this article, we will discuss about the four steps involved in the plant breeding process. Polyploidy in plants can be induced by colchicine treatment. This requires isolation of a fragment of DNA corresponding to a desirable character (or function), hooking it to a vector (such as the plasmid in a bacterium, Agrobacterium tumifaciens), and transferring it to a cell. Why? Several methods like single cross, double cross, top cross and synthetic cross. Such an organism is a hybrid. Some species, such as onion, cucurbits etc., show little or no inbreeding depression; in species like maize and bajra there is moderate inbreeding depression, while in some species, such as alfalfa and carrot, the inbreeding depression is very severe. Solanum rybinii is a wild diploid species of potato and is resistant to frost and virus infection. Increase osmotic pressure of cell sap. Book Detail: Language: English Pages: 199 Author: TNAU Price: Free How to Download PDF Book [Full Guide] Course Outline: Principles of Plant Breeding. Breeding involves the creation of multi-generation genetically diverse populations on which human selection is practiced to create adapted plants with new combinations of specific desirable traits. The selection is always between clones and never within a clone, as all the individuals of a clone have the same genetic constitution. Foundation seed is the progeny of the breeder seed and is used to produce registered seed or certified seed. Later on mutation was discovered and studied in Oenothera by Hugo de Vries in 1900 Morgan in Drosophilla (white-eyed mutant) in 1910, and by several others in various organisms. Home » Agricultural Microbiology » Plant Breeding- Steps and Significance, Last Updated on January 30, 2020 by Sagar Aryal. 7. Breeding a New Genetic Variety of a Crop: 5 Steps, Pre-Breeding & Traditional Breeding: Comparison | Methods | Plant Breeding, Plant Breeding: Definition, Objectives and Historical Background. Somoclonal variation and DNA recombinant technology. In-spite of many limitations and practical difficulties, genetic engineering offers immense possibilities for improving crops that were unthinkable before. Hybrid vigour has been exploited in commercial crops such as maize, sorghum, bajra, rice, sugar-beet, tomato, petunia, zinnia, cabbage and cucumber. Sugarcane takes about 9 months to ripe and so no other crop can be grown. Why mitochondria is called as the power house of the cell? The genes with relatively low mutation rate are known as stable genes and those with high mutation rate as unstable genes. Resultant hybrids are not all of the desirable qualities. Alloploids show a combination of, the characters of the two parental forms. For examples, potatoes are multiplied by tubers, apples by cuttings, and strawberries by runners. However, the term “mutation” was coined by de Vries. 3. In addition to this, testing of materials in farmers’ fields follows the evaluation in research fields for at least three growing seasons at several locations in the country, representing all the agroclimatic zones where the crop is usually grown. Mutations are sudden unpredictable heritable changes without any intermediate stage in characteristics of organism. The emasculation of the anthers from plant variety chosen to be a male parent and pollen grains from it is placed on the stigma of plant variety chosen to be the female parent. As a cell recovers from treatment, a new spindle is formed and the restitution nucleus undergoes normal mitosis as a polyploid cell. Self-pollinated species, on the other hand, are adapted to inbreeding and do not show any inbreeding depression. (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments. Allopolyploidy is important in interspecific and inter-generic hybridisation. A number of inbreeds are crossed in order to combine different desirable characters into one variety. So to answer this, pure lines are the progeny of self- pollinated homozygous plants that are breeding true for that particular trait. Two species of sugarcane are cultivated in India-Saccharum officianarum in Central and South India, while S. barberi is grown in northern India. 1. 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