Self-Pollinating Breeding Methods Flashcards Preview

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

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

A

** Drive to homozogosity!

  • Genetic combinations can be “fixed” … AA -> stabilized homozygote, no segregation. (Cultivars are true breeding!)
2
Q

What is a disadvantage of self-pollinated breeding methods?

A

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

3
Q

Name three types of self-pollinated breeding methods.

A
  • Mass Selection
  • Bulk Method
  • Pedigree Method
4
Q

Self-pollinated breeding methods involve…

A
  • Introduction
  • Selection *
  • Hybridization *
  • = often used in conjuction
5
Q

Discuss the steps of Mass Selection.

A
  1. Start with heterogeneous population of homozygotes.
  2. Subject population to selection pressure.
  3. Combine selected plants into new population.
6
Q

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

A

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

7
Q

Types of Mass Selection

A
  • Seed purification… population maintenance

- Rogue off-types… caused by mutation or contamination

8
Q

When is the Mass Seletion method usually used?

A

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

9
Q

Discuss advantages of Mass Selection.

A
  • Can be done in one year… fast!
  • Maintains genetic variation.
  • ‘Anyone’ (trained) can do it… easy!
  • Few resources are required.
10
Q

Discuss disadvantages of Mass Selection.

A
  • 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
Q

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

A

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
Q

Bulk Method is aka…

A

Evolutionary Method

13
Q

Discuss the steps of the Bulk Method.

A
  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
Q

Discuss advantages of the Bulk Method.

A
  • 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
Q

Discuss disadvantages of the Evolutionary Method.

A
  • 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
Q

What is the main idea of the Bulk Method?

A

** Hybridization!

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

17
Q

What is a crucial component of the Pedigree Method?

A

** Record-keeping!

Plant performance during inbreeding generations.

18
Q

Why is the Pedigree Method used?

A

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

19
Q

Discuss steps of the Pedigree Method.

A
  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.