Self-Pollinating Breeding Methods Flashcards Preview

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Flashcards in Self-Pollinating Breeding Methods Deck (19)
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1

What are the major advantages of self-pollinated breeding methods?

** Drive to homozogosity!

- Genetic combinations can be "fixed" ... AA -> stabilized homozygote, no segregation. (Cultivars are true breeding!)

2

What is a disadvantage of self-pollinated breeding methods?

Can be difficult to get genetic recombination ("fixed" gene pool).

3

Name three types of self-pollinated breeding methods.

- Mass Selection
- Bulk Method
- Pedigree Method

4

Self-pollinated breeding methods involve...

- Introduction
- Selection *
- Hybridization *

* = often used in conjuction

5

Discuss the steps of Mass Selection.

1. Start with heterogeneous population of homozygotes.

2. Subject population to selection pressure.

3. Combine selected plants into new population.

6

How could you use Mass Selection for height traits in oat?

Trim to a uniform height (median range) to select outliers for next heterogeneous generation.

7

Types of Mass Selection

- Seed purification... population maintenance

- Rogue off-types... caused by mutation or contamination

8

When is the Mass Seletion method usually used?

To improve landrace varieties... oldest known method of plant breeding!

9

Discuss advantages of Mass Selection.

- Can be done in one year... fast!
- Maintains genetic variation.
- 'Anyone' (trained) can do it... easy!
- Few resources are required.

10

Discuss disadvantages of Mass Selection.

- Only work with easy to measure / observe traits.
- Can only be used where trait is expressed.
- Does not work well with traits that have low heritability.

11

Name a modification of Mass Selection and why it is necessary.

Pure-line method!

Helps with low h traits... quick, easy, and hybridization isn't necessary.

Steps:
1. Select outliers.
2. Perform yield test.
3. Release selected line as a cultivar / germplasm

12

Bulk Method is aka...

Evolutionary Method

13

Discuss the steps of the Bulk Method.

1. Create population -> Biparental / other, self.

2. Grow F2, harvest in bulk.

3. Plant random samples of F3 seed. Repeat for several generations (~6).

4. Grow generations in intended area of adaptation -> poor genetics eliminated by natural selection.

5. Three options: pursue pure-line selection, mass selection, or releasae population as germplasm / cultivar.

14

Discuss advantages of the Bulk Method.

- Easy way to homozygosity through natural selection.
- Can be used in conjuction with mass selection and pure-line selection.
- Little record-keeping is involved.

15

Discuss disadvantages of the Evolutionary Method.

- Not suitable for off-season nurseries (needs intended environment).
- Doesn't work well with populations with large maturity differences.
- Favors ONE particular yield component.

16

What is the main idea of the Bulk Method?

** Hybridization!

This is followed by several generations of natural selection in area of intended adaptation.

17

What is a crucial component of the Pedigree Method?

** Record-keeping!

Plant performance during inbreeding generations.

18

Why is the Pedigree Method used?

To establish an elite line with the best genes from two [or more] parents.

19

Discuss steps of the Pedigree Method.

1. Make inital cross. A x B [or AB x CD]

2. Space plant F2; select individual plants (thresh separately).

3. Plant F2:3 rows... select within lines (thresh separately).

4. Repeat with F3:4 rows, F4:5 rows, etc...

5. Continue until desired homozygosity is reached.