Generating more and better food Flashcards
How did ancient Mesoamerican farmers transform teosinte into modern maize?
- 6,000-10,000 years ago, ancient Meso-American farmers changed the teosinte through selection.
Name 3 agronomical characteristics selected for in crops.
- Higher yields
- Improved morphology of fruits and seeds (e.g., seedless grapes)
- Easier cultivation (e.g., easier harvest)
Name 3 food quality/processing characteristics selected for in crops.
- Improved nutrients and flavor (e.g., purple tomatoes, improvement of protein and Omega-3 Fatty Acid in soybean)
- Reduced toxicity (e.g., potatoes which produce less acrylamide)
- Extended shelf life (e.g., blueberries with longer shelf life)
Name an environmental trait selected for in crops.
- Adaptation to environment (e.g., drought, temperature, and resistance to pests = less pesticides = safer foods)
Has been neglected in the past, but is becoming more important.
Natural selection
Historically performed by humans based on what available in nature
Historically performed by humans based on what available in nature
Natural selection
What is modern plant breeding?
- Based on the principles of heredity
- Darwin’s theory of evolution and natural selection (mid 1800s) and Mendel’s basic principles of heredity (mid 1800s) allow us to apply the principles of heredity and the knowledge of genetics and chromosomes to use the genetic variation (biodiversity) available in a species
- Molecular techniques for the selection of the best plants
Traditional breeding (does not include genetic modification, but may involve things like biomarkers)
Mutation breeding
Induction of mutations on the genomes to generate new plants from existing plants
Induction of mutations on the genomes to generate new plants from existing plants
Mutation breeding
Transfer of genes from a species to another using lab techniques.
Genetic engineering
- Transfer of genes from a species to another using lab techniques. In 1970, Agrobacterium was modified to be non harmful for plants.
- In 1988 first GE crop was tested in the field (Tomato FLAVR SAVR, late ripening).
- In 1994 it was in the commercial market.
Genetic engineering
Transfer of genes from a species to another using lab techniques.
- Transfer of genes from a species to another using lab techniques. In 1970, Agrobacterium was modified to be non harmful for plants.
- In 1988 first GE crop was tested in the field (Tomato FLAVR SAVR, late ripening).
- In 1994 it was in the commercial market.
What is crucial for improving crops?
Genetic variation
What does genetic variation arise from? [3]
- Hybridization: Recombination of alleles (variants of a gene) through sexual reproduction, introgression of genes from another species
- Mutation (changes in the DNA sequence)
- Genetic engineering.
How is hybridization used to breed new plant varieties?
- Hybridisation between a donor (parent 1) and a recipient (parent 2), can be within or among species
-
Selection of the desired progeny
Eventually… - Backcross (cross of the new plant) to the recipient line (recurrent/good parent) for restoring the genome content and the phenotype of the recipient
What does this photo show?
- Two siblings from the same crossing
(hybridization between a commercial
variety of grape and a variety that is
resistant to a pathogen [downy
mildew].) - One sibling is susceptible (left
picture), one sibling is resistant
(bottom)
Name 3 common phenotyping agronomical traits in grapes.
- Vigour
- Yield
- Cluster architecture
How are enological phenotype traits selected for in wine grapes?
- Microvinification (a winemaking technique used often for experimental batches of wine where the wine is fermented in small, specialized vats)
- HPLC & GC-MS analyses
- Wine tasting
Take home message: breeding a new grape variety requires 10-15 years of work if we are lucky!
How can recombination of alleles through sexual reproduction create a new variety with desirable traits?
- Recombination of alleles (variants of a gene) through sexual reproduction within a species
Meiosis generates […]
Meiosis generates new allele combinations in the gametes
Describe the formation of gametes in the paternal line (Cabernet franc).
Not all the gametes (i.e., pollen genes) have the colour gene due to recombination.
Describe the formation of gametes in the maternal line (Formation of gametes in the maternal line (Sauvignon blanc).
Not all gametes have the aroma gene.
Describe the breeding of the maternal and paternal lines and selection of progeny.
- Lots of variation
- The ‘problem’ of hybridization - what you obtain might be very different from the original plant.
- But when we find a plant we like we can clone it infinitely (i.e., take a branch and put it in dirt and it will grow; much easier than cloning an animal)
Describe the effect of crossing over on two genes located in the same chromosome
Not all gametes have the alleles we are looking for; gametes produced will have new combinations of alleles.
Describe why not all the gametes have the alleles we are looking for.
Crossing over and recombination (i.e., independent assortment)