Characteristics Improvement in Plant Breeding
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Dev Hingra discusses techniques for improving plant characteristics in breeding programs. Genetic variation is created through crosses between plants and new varieties are selected and tested. Classical breeding techniques include self-pollination and cross-pollination to produce new varieties. Modern techniques use molecular biology and genetic modification to insert desirable traits. Genetic modification can produce desired traits faster than classical breeding. Future plant breeding will integrate both classical and new techniques like molecular markers to improve efficiency and effectiveness in crop improvement.
Characteristics Improvement in Plant Breeding
- 1. Characteristics improvement in plant breeding Dev Hingra Department of Genetics and Plant Breeding Faculty of Agriculture Sam Higginbottom Institute Agriculture, Technology and Sciences (Formerly Allahabad Agriculture Institute) Deemed-to-be-University Allahabad Mail Id- [email protected]
- 2. Plant breeding for improvement of crops “Plant breeding is the art and science of the genetic improvement of crops to produce new varieties … Genetic variation is the engine that propels breeding to meet future challenges.” Genetic variation Crosses New variety for testing Selection In plant breeding the aim is to produce new, improved varieties/cultivars and so we need, as a first requirement of any breeding programme, to release or produce genetic variation in the characters (or traits) in which we are interested. Once such variation is released it is necessary to identify and then select the desired types – those that have a better expression of a particular character or combination of characters.
- 3. Higher yielding better quality of seeds Resistance to virus, fungi & bacteria. Resistance to diseases. Tolerance to insect pest Tolerance to environmental pressures(salinity, extreme temperature, drought) Early maturity Get maximum characteristics in one plant i.e. Development of hybrid Characteristics improvement in plant breeding deals with all the positive aspects related to plant .
- 4. For improvement of characteristics in plant breeding there are certain techniques Classical plant breeding Modern plant breeding Genetic modification
- 5. Classical plant breeding • Classical plant breeding uses deliberate interbreeding (crossing) of closely or distantly related individuals to produce new crop varieties or lines with desirable properties. • For example, a mildew-resistant pea may be crossed with a high-yielding but susceptible pea, the goal of the cross being to introduce mildew resistance without losing the high-yield characteristics. • Progeny from the cross would then be crossed with the high-yielding parent to ensure that the progeny were most like the high-yielding parent, (backcrossing). The progeny from that cross would then be tested for yield and mildew resistance and high-yielding resistant plants would be further developed. Plants may also be crossed with themselves to produce inbred varieties for breeding. • Classical breeding relies largely on homologous recombination between chromosomes to generate genetic diversity. • The classical plant breeder may also makes use of a number of in vitro techniques such as protoplast fusion, embryo rescue or mutagenesis to generate diversity and produce hybrid plants that would not exist in nature
- 6. Classical breeding method includes It includes breeding methods of self pollinated and cross pollinated crops • Plant introduction • Plant selection includes mass selection pure line selection • Hybridization: pedigree method, back cross method, single decent method • In cross pollinated crops (1) mass selection; (2) development of hybrid varieties; and (3) development of synthetic varieties.
- 7. Modern plant breeding 1.Modern plant breeding 2.uses techniques of molecular biology 3.genetic modification, to insert, desirable traits into plants. 4.Modern facilities in molecular biology has converted classical plant breeding to molecular plant breed.
- 8. Modern plant breeding Modern plant breeding uses techniques of molecular biology to select, or in the case of genetic modification, to insert, desirable traits into plants. Sometimes many different genes can influence a desirable trait in plant breeding. The use of tools such as molecular markers or DNA fingerprinting can map thousands of genes. This allows plant breeders to screen large populations of plants for those that possess the trait of interest. The screening is based on the presence or absence of a certain gene as determined by laboratory procedures, rather than on the visual identification of the expressed trait in the plant.
- 9. Steps of Plant Breeding Major activities of plant breeding are following; Creation - variation Selection Evaluation Release Multiplication Distribution of the new variety
- 10. Genetic modification of plants is achieved by adding a specific gene or genes to a plant, or by knocking out a gene with RNAi, to produce a desirable phenotype. The plants resulting from adding a gene are often referred to as transgenic plants. Genetic modification can produce a plant with the desired trait or traits faster than classical breeding because the majority of the plant's genome is not altered. The majority of commercially released transgenic plants, are currently limited to plants that have introduced resistance to insect pests and herbicides. Insect resistance is achieved through incorporation of a gene from Bacillus thuringiensis (Bt) that encodes a protein that is toxic to some insects. For example, the cotton bollworm, a common cotton pest, feeds on Bt cotton it will ingest the toxin and die. Herbicides usually work by binding to certain plant enzymes and inhibiting their action. The enzymes that the herbicide inhibits are known as the herbicides target site. Herbicide resistance can be engineered into crops by expressing a version of target site protein that is not inhibited by the herbicide. This is the method used to produce glyphosate resistant crop plants Genetic modification of plants that can produce pharmaceuticals (and industrial chemicals), sometimes called pharmacrops, is a rather radical new area of plant breeding.
- 11. New Genetic Approaches for improvement of characteristics are: Tissue culture (in vitro) techniques micro propagation, haploid production, protoplasts, embryo culture, apical culture, somatic embryogenesis, Improving plant breeding with exotic genetic libraries Use Wild species in breeding Use of Molecular markers in plant breeding
- 12. • Haploidy Establishing true breeding, homozygous, lines is an essential part of developing new cultivars in many crop species. These homozygous lines are used either as cultivars in their own right (i.e. for inbreeding crop species) or as parents in hybrid variety development. a haploid plant can develop which can then be treated to encourage its chromosomes to double, to produce a completely homo- zygous line (a doubled haploid) • Improving plant breeding with exotic genetic libraries Naturally occurring variation among wild relatives of cultivated crops is an under- exploited resource in plant breeding. exotic libraries, which consist of marker-defined genomic regions taken from wild species and introgressed onto the background of elite crop lines, provide plant breeders with an important opportunity to improve the agricultural performance of modern crop varieties. These libraries can also act as reagents for the discovery and characterization of genes that underlie traits of agricultural value.
- 13. • Use of Molecular markers in plant breeding Although plant breeders have practised their art for many centuries, genetics is a subject that really only came of age in the twentieth century with the rediscovery of Mendel’s work. Since then research in genetics has covered many aspects of the inheritance of qualitative and quantitative traits, but plant breeders usually still have little, or no, information about: the locations of many of these loci in the genome or on which chromosome they reside; . the number of loci involved in any trait; . the relative size of the contribution of individual alleles at each loci on the observed phenotype, except where there is an obvious major effect(e.g. height and dwarfing genes) • Wild species in breeding The potential of wild species as a source of genetic variation to bring about crop improvement was recognized early in the twentieth century
- 14. Future Potential Plant breeding will continue to be highly dependent on classical techniques but will undoubtedly increase in efficiency and electiveness by the addition of these new approaches, which will be used in parallel with the more classical ones. Thus the future will see the range of techniques expanding in such a way as to maximize their benefits by their integrated exploitation
- 15. conclusion There are many classical and modern breeding techniques that can be utilized for crop improvement in agriculture despite the ban on genetically modified organisms. For instance, controlled crosses between individuals allow desirable genetic variation to be recombined and transferred to seed progeny via natural processes. Marker assisted selection can also be employed as a diagnostics tool to facilitate selection of progeny who possess the desired trait(s), greatly speeding up the breeding process. This technique has proven particularly useful for the introgression of resistance genes into new backgrounds, as well as the efficient selection of many resistance genes pyramided into a single individual. Unfortunately, molecular markers are not currently available for many important traits, especially complex ones controlled by many genes.
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