STARTING MATERIAL AND ORIGIN OF DIVERSITY

Question 1

Starting material for plant breeding

Answer 1

Domesticated plants
-Commercial cultivars
-Breeding materials
-Landraces
- Genetic stocks
Undomesticated plants
Other species or genera

Question 2

Commercial cultivars

Answer 2

Results of plant breeding
Current cultivars: superirior gene combinations, adapted to area, genetically good performance
obsolete cultivars: cultivars taken out of commercial production because they may have suffered a set-back or been replaced

Question 3

breeding material

Answer 3

after a breeding program, a breeder releases one or a few genotypes that made it to the final stage and will be retained as breeding material to be considered in future projects

Question 4

landraces

Answer 4

Farmer developed and maintained cultivars. They are developed over long periods and represent both anthropogenic selections and an adaptation to a specific environment.
- Usually heterozygous
- developed resistance to the environmental stresses in their specific areas of adaptation
- They may be used as starting material in mass selection, pure line or synthetic line breeding projects

Question 5

Genetic stocks

Answer 5

products derived from specialized genetic manipulations by researchers (using mutagens like x-rays and gamma-rays)

Question 6

undomesticated plants

Answer 6

When desired genes are not found in domesticated cultivars, researchers will use undomesticated plants
-beneficial because of disease resistance genes and survives environmental conditions
- Linkage drag is a major problem during crossing.

Question 7

other species or genomes

Answer 7

requires cross compatability or cross fertile

Question 8

origins of genetic variability

Answer 8

-naural genetic variation
-cross breeding ( F2 population, MAGIC population)
- Mutagenesis
-Polyploidization
- trans/cis genesis
-protoplast fusion
- genome editing

Question 9

natural genetic variability

Answer 9

genomic recombination -> independent assortment-> spontaneous mutation ( genic mutation, chromosomic mutation, genomic mutation)

Question 10

F2 populations usefulness

Answer 10

1. studying mendelian segregation
2. Constructing genetic linkage maps and identifying the location of genes controlling important traits.
3. Detecting QTLs
4. serve as the foundation for selecting new varieties in breeding programs

Question 11

MAGIC population

Answer 11

Multi-parental advanced generational inter-crossing.
1. Useful for detecting QTLs
2. greater genetic diversity compared to biparental.making them more similar to natural populations.
3.serve as the foundation for selecting new varieties in breeding programs

Question 12

polyploidization

Answer 12

chromosome doubling induced by antimitotic agents (colchicine) to produce a tetraploid from a diploid.
Then crossing of the female inbred tetraploid with a male inbred diploid to produce a triploid.
Triploids cannot divide equally during meiosis, resulting to non functional male and female gametes.

Question 13

protoplast fusion

Answer 13

fusion of cells or cell components to transfer traits between species