Post on 18-Dec-2015
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
S = smooths = wrinkled
• Dominant vs Recessive genes
Gregor Mendel
• Dominant vs Recessive genes (2)
F1
S = smooths = wrinkledY = yellowy = 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 Garden
Types of Propagation
#1 #2 #4 #5 #6 #7 #8 #9 #10
Sex in the Garden
Types of Propagation• Sexual
– Self-pollination -- Wind pollination– Cross-pollination -- Insect pollination
• Asexual– Cuttings -- Layering– Grafting -- Biotechnology
Sex in the Garden
Sexual 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 Acid a polymeric molecule consisting of nucleotides (ribose, PO4, and adenine, cytosine, guanine, & uracil). Found in nucleus, chloroplasts, mitochondria, ribosomes. Makes proteins.
Building Blocks
Sex in the Garden
Sexual PropagationTerms– 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 Garden
Sexual PropagationTerms– 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 Garden
Sexual PropagationTerms– 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 Garden
Sexual PropagationTerms
• 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)
Cell Division-Mitosis
Cell Division-Meiosis
Sexual PropagationMeiosis
Flower
Pollen Ovule
microspores megaspores
#1 #2 #4 #5 #6 #7 #8 #9 #10
Sexual Propagation
Fertilization
Endosperm3n
Embryo
Pollen grain
Generative cellTube nucleus
Pollen tube
Sperm cells
Polar nuclei
Egg
Embryo sac4-nucleate
2-nucleate
Zygote 2n
Genetic Engineering
• 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!
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 UglyCorn Saltcedar Chestnut blightChile Tumbleweed Dutch Elm DiseasePeanut Kudzu Sudden Oak DeathApple Tree of Heaven White Pine Blister RustPotato 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??
#1 #2 #4 #5 #6 #7 #8 #9 #10
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 Garden
Asexual Propagation• Terms
– Cutting– PGR (hormone)– Sport– Scion– Rootstock– Graft Union– Tissue Culture
Sex in the Garden
Asexual Propagation• Vegetative Propagation
– Timing (season) -- Age (branch)– PGR -- Leaf Area– Stem Wounding -- Cutting Size– RH -- T
Rooting of Blue Spruce/ Wagner1987
Rooting %
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15
20
Dec Jan Feb Mar Apr May
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4
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8
10
12
0 2000 4000 6000 8000 10000
Collection Month
IBA Treatment (ppm)
Rooting %
0
5
10
15
20
25
30
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4 5 6 7 8 9 10 11 12 13
Cutting Length (cm)
Genetics & Plant Breeding
• Things to Know– DNA– Gene– Chromosome– Ploidy
• Haploid (N)• Diploid (2N)• Polyploid (3N, 4N, 6N)
• Things to Know– RNA– Mitosis– Meiosis