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Genetics & Plant Breeding. J.G. Mexal A/H 100 G Spring 2006. Topics. History Cell Division (mitosis) Reproduction (meiosis) Role of DNA Role of RNA Plant Breeding & Genetics. Gregor Mendel (1822-1864). Worked in monastery garden Time period = 1856-1863
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Genetics & Plant Breeding J.G. Mexal A/H 100 G Spring 2006
Topics • History • Cell Division (mitosis) • Reproduction (meiosis) • Role of DNA • Role of RNA • Plant Breeding & Genetics
Gregor Mendel (1822-1864) • Worked in monastery garden • Time period = 1856-1863 • Published: “Experiments on Plant Hybrids” in obscure journal • Worked ‘discovered’ in 1900
Gregor Mendel • Dominant vs Recessive genes S = smooth s = wrinkled
F1 Gregor Mendel • Dominant vs Recessive genes (2) S = smooth s = wrinkled Y = yellow y = green
Gregor Mendel • Incomplete dominance
Important Milestones • 1866 Gregor Mendel • 1947 Barbara McClintock (jumping genes) • 1953 Watson & Crick (structure of DNA) • 1970s Foreign gene expressed in tobacco • 1986 Transgenic plants field tested • 1990s Bt gene inserted into crops • 1994 Flavr-Savr tomato released
Sex in the GardenTypes of Propagation #10 #1 #2 #4 #5 #6 #7 #8 #9
Sex in the GardenTypes of Propagation • Sexual • Self-pollination -- Wind pollination • Cross-pollination -- Insect pollination • Asexual • Cuttings -- Layering • Grafting -- Biotechnology
Sex in the GardenSexual Propagation • Terms • DNA : Deoxyribonucleic Acid a polymeric molecule consisting of nucleotides (ribose, PO4, and adenine, cytosine, guanine, & thymine). Found in nucleus, chloroplasts, mitochondria. Makes RNA. • RNA: Ribonucleic Acida polymeric molecule consisting of nucleotides (ribose, PO4, and adenine, cytosine, guanine, & uracil). Found in nucleus, chloroplasts, mitochondria, ribosomes. Makes proteins.
Sex in the GardenSexual Propagation Terms • Chromosome: genetic material of cell organized in linear structures • Gene: genetic material on a chromosone determining a characteristic • Genotype: the genetic makeup of an organism • Phenotype: the physical manifestation of the genotype modified by the environment
Sex in the GardenSexual Propagation Terms • Diploid: a cell containing 2 sets (2n)of chromosomes (vegetative cell) • Haploid: a cell containing 1 (1n)set of chromosomes (pollen or ovule) • Polyploid: a cell containing more than 2 sets of chromosomes. Usually vegetatively reproduced. • Banana = 3n • Potato = 4n • Strawberry = 8n
Sex in the GardenSexual Propagation Terms • Mitosis: cell division where nuclear complement (1n or 2n) is maintained • Meiosis: cell division where nuclear complement (2n only) is reduced to 1n (gametes) • Hybridization: controlled cross-fertilization • Independent Assortment: each chromosome operates independently during mitosis & meiosis • Mutation: a heritable change in a gene
Sex in the GardenSexual Propagation Terms • Monoecious: Both sexes on same plant (e.g. corn, pecan) • Dioecious: Sexes on different plants • Holly (female) Juniper (male or female) • Pistachio (female) Cottonwood (male) • Asparagus (male)] • Ash (male)
Sexual PropagationMeiosis Ovule Pollen #10 #1 #2 #4 #5 #6 #7 #8 #9 Flower microspores megaspores
Sexual PropagationFertilization Generative cell Sperm cells Tube nucleus Polar nuclei Pollen grain Egg Pollen tube 2-nucleate 4-nucleate Embryo sac Endosperm 3n Zygote 2n Embryo
The Tools Agrobacterium “Gene Gun” Electroporation Microinjection Liposomes The Plan: Find a gene of interest Develop cell culture of crop Insert the gene (tools) Hope it gets incorporated in plant DNA Have gene product expressed Regenerate plants from cells Field test to see if it works! Genetic Engineering
Plant:People Interactions • People to Plant • Moving plants • Endangering plants– Chestnut, Echinacea • Creating ‘new’ plants— Bt corn, RoundUp Ready Cotton The Good The Bad and The Ugly Corn Saltcedar Chestnut blight Chile Tumbleweed Dutch Elm Disease Peanut Kudzu Sudden Oak Death Apple Tree of Heaven White Pine Blister Rust Potato Potato Karnal bunt
Biotechnology Advances • Flavr-Savr Tomato • Ring spot virus-resistant Papaya • Golden Rice (vitamin A) • Round-up resistant crops (herbicide) • BT crops (insecticide) • ‘Designer’ plants
Genetic Engineering • The Future: • Antibiotics in fruits • Salt tolerance?? • Drought tolerance?? • Freeze tolerance (INA) • Mexal’s botanical kindergarten?? #10 #1 #2 #4 #5 #6 #7 #8 #9
Plant:People Interactions • Creating ‘new’ plants— for the future • Sensitive Noses: Beano-Beans • Movie Goers:Glo-in-the-dark Popcorn • Indecisive New Mexicans: ‘NuMex Red’nGreen’ Chile • Americans: Atkins-friendly Maple Syrup • Christmas: Epiphany Poinsettia • Kinder-garden: Nile water lily X Venus fly-trap
Plant:People Interactions • People to Plant • Creating ‘new’ plants— for the future • Sensitive Noses: Beano-Beans • Movie Goers:Glo-in-the-dark Popcorn • Indecisive New Mexicans: Red’nGreen Chile • Americans: Atkins-friendly Maple Syrup • Christmas: Epiphany Poinsettia • Kinder-garden: Nile water lily X Venus fly-trap
Sex in the GardenAsexual Propagation • Terms • Cutting • PGR (hormone) • Sport • Scion • Rootstock • Graft Union • Tissue Culture
Sex in the GardenAsexual Propagation • Vegetative Propagation • Timing (season) -- Age (branch) • PGR -- Leaf Area • Stem Wounding -- Cutting Size • RH -- T
Rooting % Collection Month Cutting Length (cm) IBA Treatment (ppm) Rooting of Blue Spruce/ Wagner1987 Rooting %
Things to Know DNA Gene Chromosome Ploidy Haploid (N) Diploid (2N) Polyploid (3N, 4N, 6N) Things to Know RNA Mitosis Meiosis Genetics & Plant Breeding