PLNT 1213 Lecture Notes - Lecture 17: Genetically Modified Organism, Beta-Carotene, Agrobacterium

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25 Aug 2016
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Crop Improvement
Crop Improvement
Developing plants with traits that increase quality and quantity of food production in a
given environment
Two areas:
oPlant breeding
The art and science of genetic plant improvement
oPlant genetics
The study of heritability of traits in plants
Traits: traits are the result of genes
Genes are composed of DNA
oDeoxyribonucleic acid
oThe library of information that contains the instructions for
an organism’s form and function
Genotype: All of the genetic information within an
Phenotype: The physical appearance of an organism
Result of interaction between genotype and
Necessary info for crop improvement
The extent to which a given trait is influenced by genetics and by environment
If trait is controlled by one gene or by multiple genes
Plant breeding process
Identify the objective
oImprove yield
oDisease resistance
oDrought or cold tolerance
oImproved quality
Collect genetic variation
oAdapted cultivars
oBreeder seed
oPlant introductions
oInduced mutations
Make new combinations
oSelection from genetic variation
oMake new combinations by crossing
Mass selection
Collect all genes that contribute to a trait
oUseful in cross-pollinated crops
oChoose many plants based on phenotype
Pure lines
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A “pure line” is a plant that has been bred by self-pollination of a
single plant
oMore uniform than a cultivar developed by mass selection
The controlled pollination of two genetically different plants (often
inbred plants)
oHybrid vigor
Only in first generation
Select desirable combinations
oSee mass selection, pure lines, hybridization
Evaluate selections
oCompare the new selection to currently used selections
oVariety testing
Limitations of traditional plant breeding
Limited selection of genetic resources
Low efficiency
oSelect the phenotype to try to get genotype
oRequires a lot of space and money
Genetically modified organisms
Genes are transferred from one organism to another
More correctly called transgenic crops
Biotechnology and genetically modified organisms
All aspects of agriculture involve “biotechnology
All crops are “genetically modified”
oExamples of transgenic crops
Canola – herbicide tolerant
Corn – Bt, herbicide tolerant
Cotton – Bt, herbicide tolerant
Rice – Provitamin A
Soybean – herbicide tolerant
Tomato – FlavrSavr
Wheat – no GMO wheat
Moving one or a few genes from one species to another
Done by physically inserting a piece of DNA into the target species
Can be accomplished directly (gene gun) or indirectly (using agrobacterium)
How can this technology be made available to the developing world?
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Who “owns” the genetic resources?
What is changing in addition to the desired trait?
What happens to the pollen?
How do we keep transgenic and “conventional” crops separate?
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