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3.1 plant breeding and gm technology leaver 3.1 plant breeding and gm technology leaver Presentation Transcript

  • Genetic Engineering, Crop Improvement and Biotechnology Chris Leaver chris.leaver@plants.ox.ac.uk
  • Map of the world showing the major centres of origin of crops, which are distributed mainly in tropical regions
  • Plant Improvement using Breeding and Selection - HISTORICAL PERSPECTIVE 8000 BC (5 million people) Domestication of cereals and Pulses 2000 BC (50 million people) Domestication of rice, Potato, Oats, Soybean, Grape, Cotton, Banana. 1583 (500 million people) Sexuality in plants Described 1742 First Company (Vilmorin) Devoted to Plant Breeding and New varieties 1799 First Cereal Hybrid Described 1927 X-Rays Used for Mutation Breeding 1983 (5 billion people) First Use of Gene Technology for Plants 2012 (7 billion people) 160 plus million hectares of GM Crops grown in 29 Countries by 16 million farmers
  • The evolution of maize (corn) Domestication The adaptation to Europe Extension of corn crop areas years The wild ancestor Teosinte First corns America Mexico Populations South of Europe Introduction Hybrids First creation of hybrids in France SOURCE: GNIS (Groupement National Interprofessionnel des Semences)
  • Genetic modification arose as a consequence of cultivation and selection of the best plants Planting seeds from “good” plants increased their representation in subsequent generations Natural variation within population Image courtesy of University of California Museum of Paleontology, Understanding Evolution - www.evolution.berkeley.edu
  • F1 Hybrid Seed Production in self-pollinating crop species – a basis for crop improvement and the development of heterosis or hybrid vigour F1 hybrid seed production in a range of major crops including Maize, Rice, Sorghum, Sunflower, Sugar Beet, Carrot, Onions, Brassica’s etc
  • F1 Hybrid Seed Production in Maize Pollen - male parent Female parent Tassel removed F1 Hybrid X Ear Inbred Parental Corn Lines Hybrid Vigour
  • F1 Hybrid Maize Production Field Detasseled Maize
  • Hybrids
  • Selection and Plant Breeding was Applied to a Range of Important Crops we Grow Today Teosinte Rice Corn Tomato The Creation of Corn The corn that Columbus received was created by the Native Americans some 8,000 years ago by domestication of a wild plant called teosinte. They used ‘genetic engineering’ in a quite remarkable way to produce a more productive variety.
  • PRODUCTS OF MODERN BREEDING Tomatoes Peppers Potato
  • Sustainable food security is facing a major bottleneck • • • • • • Since the beginning of agriculture, humans have cultivated 7,000 plant species Since the beginning of agriculture, humans have cultivated 7,000 plant species Today only 150 plant species (2%) are agriculturally relevant for food and clothing Today only 150 plant species (2%) are agriculturally relevant for food and clothing Only 10 plant species are cultivated today to provide 95% of food and feed Only 10 plant species are cultivated today to provide 95% of food and feed Cultivated today 95% of food and feed Total cultivated since the beginning of agriculture
  • Mankind depends on a few crop species for our food
  • The top four – Global yield (UN-FAO Statistics) Soybean Wheat 2nd 4th Maize Rice 1st 3rd
  • The myth of natural food The food we eat comes from plants already extensively modified from their original form. Even heritage varieties are extensively genetically modified. Credit: Nicolle Rager Fuller, National Science Foundation
  • What traits/characteristics are selected by plant breeders? • • • • • • • • • • • Improved Nutrition Improved Yield Improved Rate of growth Self-pollinating Reduced pod shatter Able to harvest & store the fruit Palatability Better Taste Reduced toxins Reduced / negligible dormancy requirement Disease resistance THESE TRAITS ARE ENCODED BY GENE(S)
  • DNA: the language of life Cell Chromosome Nucleus Gene DNA
  • There are 25-40,000 genes found in the nucleus of each plant cell depending on the species DNA APPEARS BLUE CSIRO. Introduction to
  • A gene is a code for a protein Ca.25000 GENES CSIRO. A plant Gene
  • The set of genes is the master plan which contains all the information to make a plant What is a gene? Control Switch Code for Protein Downstream control region DNA Start RNA Protein Enzymes Stop
  • Genes provide the foundation of new plants/products for farmers Genes Protein Yield? Tolerance to drought? Flowering time? Trait Nutrition Taste? Tolerance to Pests and Diseases Product
  • Maize Genome/DNA sequence data (the masterplan) are available for many important crop plants
  • Advanced Genomics Will Accelerate Discovery of Genes of Use to Farmers Gene sequence Genome Gene DNA map t c g c g t g a t g t c t g t c a t a t g g g t g a a t a t t a c c t g g c g t GENE g g a c g c t Gene expression g SEQUENCE FUNCTION Plant traits Yield Drought Disease Stress Stress Oil quality Disease Yield Maturity Herbicide tolerance TRAIT
  • Finding the needle in a haystackplant gene discovery If selective breeding and genetic modification are based on genes, how does one go about finding the genes of interest?
  • The Challenge: Finding the genes that provide the foundation of new traits and crop improvements for farmers A Central Role for Omics, BioInformatics and Systems Biology Technology Platforms Bioinformatics Modelling physiology 0 Transcriptomics Metabolomics Proteomics leaf 2 s te m leaf 3 f1 Process Grain filling lea Genome Sequencing Molecular profiling Time post anthesis PhenomicsTRAIT ANALYSIS
  • Building Increased Productivity and Sustainability into the Seed by Plant Breeding and Biotechnology The scientific basis of all crop improvement is identification of the genes that encode and regulate specific phenotypic characteristics or traits of use to the farmer: Genetic modification by marker assisted breeding (MAB) and GM technology where appropriate:
  • NEW TOOLS FOR CROP IMPROVEMENT Elite Germplasm Gene Sequencing r ula g c ole edin M re B Marker Assisted BREEDING Seeds Better Varieties, Faster Seed Production GENOMICS Functional Genomics Finding the Genes Ge ne s Trait Development PLANT BIOTECH Plant Transformation Traits New Traits of Use to the Farmer
  • Using molecular-gene markers Healthy wheat Infected wheat Isolate DNA from young plants RRRR rr rr RR rr RR rr RR rr rr Selected plants
  • What is Genetic Modification? Genetic modification is the addition, alteration or removal of genetic material, usually single genes, in order to alter an organism’s characteristics. Living organisms contain 5,000-30,000 genes arranged in linear order in chromosomes which are long strands of DNA. Genes are heritable segments of DNA that contain the code for an individual protein molecule. Nucleus ca.25,000 Genes Chloroplasts ca.80 Genes Mitochondria ca.60 Genes Genetic Information in a Plant Cell
  • A quick reminder Conventional breeding During conventional breeding, genes are always mixed and newly assorted. This often results in nondesired traits of elite crop varieties.The desired improvement is obtained by many years of selection in the field. Elite variety Breeding line New variety = X (Cross) Favorite gene Favorite gene Non-desired gene Gene technology Using gene technology, it is possible to transfer only a favorite/desired gene into an elite crop variety. All other traits of the the elite crop variety will be preserved. Favorite gene Elite variety New variety = (Gene transfer) Favorite Gene
  • Gene Transfer by Classical Plant Breeding 25,000 genes 25,000 genes Selection S = gene for susceptibility to pest R = gene for resistance to pest R=gene for resistance The backcrossing programme (BC) can take 8 to 10 years Single gene
  • S = gene for susceptibility to pest 25,000 genes R=gene for resistance Single gene 25,000 genes R = gene for resistance to pest Repeated Backcrossing and selection for desired traits
  • Genetic modification is the addition, alteration or removal of genetic material usually single genes, in order to alter an organism’s characteristics. The genes can be from any donor organisms Microorganisms Plants DNA Animals Man Approximately 30% of animal, plant and fungus genes are similar A large percent of our genes are the same as those of simple organisms such as bacteria and viruses
  • REASONS FOR UNDERTAKING ANY GENETIC MODIFICATION 1 To improve the efficiency of a specific metabolic pathway so as to improve the “efficiency” of the plant as a whole in terms of its yield, nutritional quality or agronomic characteristics(eg height, seed size) 2 To bypass some limiting such as intolerance to heat or cold,drought,flooding, or to improve resistance to pests and diseases 3 To change the nature of the harvested product – as a human foodstuff; to provide a product of therapeutic value; to provide industrial feed-stocks (e.g. the production of biodegradable polymers) and biofuels.
  • Conventional Plant Breeding has been very successful but yield gains are now slowing. The new molecular technologies allow more precise and rapid crop improvement by marker assisted selection breeding and GM approaches. This requires the identification of the gene(s) that underlie the traits and then combination with native traits using molecular markers and/or GM to improve the crop– these include: •Avoidance of losses from pests-insects,bacteria,fungi,viruses •More effective water use-drought tolerance •Increased tolerance towards temperature stress •Increased yield •Time to maturity – shortened growing season •Growth on marginal soils-salinity, pH, metal toxicity •More effective fertiliser use-nutrient(NPK) use efficiency •Increased flooding tolerance •Competing with weeds •Improved nutritional quality-biofortification (eg.Vitamins,Iron) •Sustainable production with a low carbon footprint
  • Specificity of Genetic Modification Identification and isolation of specific genes with defined function Insertion of specific genes into a crop species to promote desirable characters GM progeny can be selected for the product or activity of specific genes with a defined function There are no “surprises” from unknown genes transferred along with the planned cross
  • The scientific basis of all crop improvement is identification of the genes that encode and regulate specific phenotypic characteristics or traits of use to the farmer. REDUCED STRESSES Biotic and Abiotic • Drought or • Pests and Flooding Diseases • High or low • Weeds Temperature • Saline or . Phyto-remediation acid soils . Increased greenhouse gases- Tolerance to climate change IMPROVED NUTRITION AND HEALTH IMPROVED PLANT PERFORMANCE MORE SUSTAINABLE PRODUCTION Environment • Nutrient use efficiency • Water use efficiency • Control of flowering • Plant architecture • Heterosis • Yield Plant Gene Technology NEW INDUSTRIES Quality Traits • Vitamins & Minerals • Biofortification • Post harvest quality • Taste • Proteins • Oils and Fats • Carbohydrates • Fibre & Digestible energy • Bloat Safety CHEMICAL FEEDSTOCKS • Biodegradable Plastics • Biofuels PHARMACEUTICALS • Vaccines • Antibodies • Diagnostics
  • Genetic transformation of plants
  • The steps involved in genetic modification Identify the gene an interesting gene from a donor organism Isolate the interesting gene Insert the gene in a genetic construction Multiply the genetic construction (bacteria, plant ...) Transfer the gene Evaluate Plant regeneration gene expression Add to other varieties by crosses Selection of transformed cells SOURCE: GNIS (Groupement National Interprofessionnel des Semences)
  • Gene Isolation by standard techniques of molecular biology The first step is to isolate DNA like you did yesterday.Then cut the DNA into gene size pieces with special enzymes and identify the genes and what they do. The trait or characteristic which they contain the information for.
  • Getting genes into plants Tissue Fragment of target plant THE GENE TRANSFERRED DNA CELL DIVISION CELLS REGENERATE INTO PLANTLETS Selection of Transgenic Cell Transfer to Soil PLANTS WITH NEW TRAIT
  • Schematic representation of the two main ways to create transgenic plants Agrobacterium Method Particle Gun Method
  • Agrobacterium Method Agrobacterium tumefaciens-a common soil bacterium
  • Nature’s original genetic engineer Gall formation Agrobacterium Crown Gall The soil bacterium Agrobacterium is able to infect plants and make them produce the food it needs to live on. The bacterium does this by inserting a small piece of its own DNA into the genome (DNA) of the plant. Scientist have modified this naturally occur process to make genetically modified plants.
  • Agrobacterium-mediated plant transformation Agrobacteria containing recombinant Ti plasmid are multiplied in liquid culture Cocultivation: Agrobacterium culture is added to callus culture (e.g. rice) in Petri dish. Agrobacteria infect the callus cells. T-DNA excises from the Ti plasmid and integrates into chromosomal DNA in the nucleus of the callus cell. In planta transformation: Flowering Arabidopsis is inverted so that flowers dip into the Agrobacterium culture in a bell-jar. Application of vacuum helps bacterial infiltration. Plants are removed and grown. Flowers are allowed to self and seeds are germinated in selection agent so that only transformed seedlings (about 10% of the total) develop. Selection: transformed cells (white) are resistant to selection agent (herbicide or antibiotic. Non-transformed cells (color) eventually die.
  • DNA delivery to plant cells: Agrobacterium Agrobacterium chromosome Genes for transfer T-DNA Regeneration Agrobacterium cell Plant Cell
  • Totipotency: Regeneration of a New Plant from a Single Cell
  • More recently techniques have been developed in whereby Agrobacterium is vacuum infiltrated into developing floral buds of a number of different plant species
  • DNA delivery to plant cells: biolistics DNA coating of microscopic metal particles DNA code for RR Metal particles DNA DNA insertion Plant cell Particles are shot into plant cells Transferred DNA Transformed plant cell Cell division
  • Broad Leaved Crops Cereal Transformation
  • Crop Transformation • High efficiency transformation protocol • Output > 25,000 transformed plants per year
  • Automated Plant Evaluation System
  • REGULATORY COSTS
  • From laboratory to commercialisation specific gene transfer in the lab. followed by subsequent testing in the field this is the only plant breeding technology which requires regulatory approval (and, in some countries, labelling of all the food products derived from modified plants): • testing for food toxicity, nutritional value, composition and allergenicity – includes animal feeding trials • characterisation of the transferred gene as well as its effects on the host genome •an environmental audit as well
  • A quick reminder Conventional breeding During conventional breeding, genes are always mixed and newly assorted. This often results in nondesired traits of elite crop varieties.The desired improvement is obtained by many years of selection in the field. Elite variety Breeding line New variety = X (Cross) Favorite gene Favorite gene Non-desired gene Gene technology Using gene technology, it is possible to transfer only a favorite/desired gene into an elite crop variety. All other traits of the the elite crop variety will be preserved. Favorite gene Elite variety New variety = (Gene transfer) Favorite Gene
  • Why are GM methods used sometimes and molecular breeding others? Molecular breeding 1. Desired trait must be present in population 2. Genetic resources must be available 3. Plant should be propagated sexually GM 1. Gene can come from any source 2. Genetic resources not required 3. Plant can be propagated vegetatively Photo credits: Gramene.org ETH Life International
  • How have we fared thus far? Rice genome Sequenced Plant Transformation 1983 1865 Mendel’s Discovery of Genes 1905 Genetics 1953 Structure of DNA 1001 Arabidopsis genomes sequenced 2002 2011 1995 2000 Crop Circles ‘Synteny’ 2010 First Plant NGS Genome Sequence
  • The science behind gene technology • A gene is a code for a protein • We can purify and reconstruct genes • We can transfer genes to plants to introduce a useful characteristic, eg insect protection or weed control • The resulting plants are thoroughly tested
  • Genes are part of our diet Copyright CSIRO
  • Can Genetic Improvement of Crops Help Feed the world? • No single solution will solve this problem but the new genetic technologies of plant breeding developed during the last few years can helpthey are but one tool in the toolbox. • They can can increase agricultural efficiencies and save people from hunger in a sustainable manner, particularly in African nations where the need is greatest. Genomics, markerassisted screening, phenotype analysis, computer modeling, and genetic modification (GM) when required, have greatly accelerated the breeding process.