Genetics and Genetic Prediction in Plant Breeding 2010

 Qualitative

Genetics

Controlled by alleles at a single locus  Quantitative

genetics

Controlled by polygenic systems  Population

Genetics

Frequency of alleles in populations  Cytogenetics

Properties of chromosomes.  Molecular

Genetics

Involves studies at the molecular level

Qualitative

Genetics Segregation, linkage, epistasis, tetraploid, 2 Quantitative Genetics Continuous variation, genetic models, model testing QTL’s

Heritability

Broad-sense & narrow-sense Diallel Griffing analysis, GCA, SCA Hayman & Jink’s Cross prediction

Gregor Johann Mendel Augustinian Monk, St. Thomas in Brünn. Started genetics work with pea in 1856. Published genetics paper 1866 (ignored).

Vries, Correns, Tschermak (independently) rediscover Mendel's work.

Parents round x wrinkled

yellow x green

F1 Progeny round

yellow

long x short stem

long

axil x terminal

axil

F2 Progeny 5,474 rd 1,850 wr

6,022 ye 2,001 gr 787 lo 277 sh 651 ax 207 ter

F2 Dom:Rec 2.96 : 1

3.01 : 1 2.84 : 1 3.15 : 1

 Chose

Pisum Sativum as a research species.

diploid species. homozygous parental lines.  Did

research beyond the F2 generation.  Concentrated on qualitatively inherited characters.  Kept meticulous records of plant counts and could trace lineage of all progeny.

 Genotype

?  Phenotype. Environment.  Large effect on quantitative traits, small effect on qualitative traits. Dominance (allelic interactions).  Expression on one allele is masked by another allele at the same locus.

Epistasis (non-allelic interactions).  Expression of one allele is masked by another allele at a different locus.

Parents

tall x dwarf

6-row x 2-row

Parents

tall x dwarf

6-row x 2-row

F1

tall

6-row

Parents

tall x dwarf

6-row x 2-row

F1

tall

6-row

F2

3 tall:1 short

3 6-row : 1 2-row

Parents

tall x dwarf

6-row x 2-row

F1

tall

6-row

F2

3 tall:1 short TT:Tt:tt 1:2:1

3 6-row : 1 2-row SS:Ss:ss 1:2:1

Parents

AA x aa

Aa

F1 F2 Frequn

AA ¼

F3 Frequn

AA AA ¼ 1/8

Aa ½ Aa ¼

3/8

¼

aa ¼

aa ¼

aa 1/8

3/8

F1 TtSs Self

TS

Ts

tS

ts

Gametes from female parent TS Ts tS ts

Gametes from male parent TS

Ts

tS

ts

Gametes from male parent

Gametes from female parent

TS

TS

TSTS

Ts tS ts

Ts

tS

ts

Gametes from male parent

Gametes from female parent

TS

Ts

tS

ts

TS

TSTS

TSTs

TStS

TSts

Ts

TsTS

TsTs

TstS

Tsts

tS

tSTS

tSTs

tStS

tSts

ts

tsTS

tsTs

tstS

tsts

Gametes from male parent

Gametes from female parent

TS

Ts

tS

ts

TS

TTSS

TTSs

TtSS

TtSs

Ts

TTSs

TTss

TtSs

Ttss

tS

TtSS

TtSs

ttSS

ttSs

ts

TtSs

Ttss

ttSs

ttss

Gametes from male parent

Gametes from female parent

TS

Ts

tS

ts

TS

TTSS

TTSs

TtSS

TtSs

Ts

TTSs

TTss

TtSs

Ttss

tS

TtSS

TtSs

ttSS

ttSs

ts

TtSs

Ttss

ttSs

ttss

1 TTSS:2 TTSs:1 TTss:2 TtSS:4 TsSs:2 Ttss:1 ttSS:2 ttSs:1 ttss

Gametes from male parent

Gametes from female parent

TS

Ts

tS

ts

TS

TTSS

TTSs

TtSS

TtSs

Ts

TTSs

tS

TtSS

ts

TtSs

TtSs TtSs

Gametes from female parent

Gametes from male parent TS

Ts

tS

ts

TS Ts

TTss

tS ts

Ttss

Ttss

Gametes from female parent

Gametes from male parent TS

Ts

tS

ts

tS

ttSS

ttSs

ts

ttSs

TS Ts

Gametes from female parent

Gametes from male parent TS

Ts

tS

ts

TS Ts tS ts

ttss

Gametes from male parent

Gametes from female parent

TS

Ts

tS

ts

TS

TTSS

TTSs

TtSS

TtSs

Ts

TTSs

TTss

TtSs

Ttss

tS

TtSS

TtSs

ttSS

ttSs

ts

TtSs

Ttss

ttSs

ttss

9 T_S_ : 3 T_ss : 3 ttS_ : 1 ttss

F2 Gametes

TT – ¼

Tt – ½

tt – ¼

SS – ¼

1/16 TTSS 2/16 TtSS

1/16 ttSS

Ss – ½

2/16 TTSs

4/16 TtSs

2/16 ttSs

ss – ¼

1/16 TTss

2/16 Ttss

1/16 ttss

1TTSS: 2TTSs:1TTss:2TtSS: 4TsSs: 2Ttss:1ttSS: 2ttSs:1 ttss 9 T_S_ : 3 T_ss : 3 ttS_ : 1 ttss

F3 Gametes

TT – 3/8

Tt – 2/8

tt – 3/8

SS – 3/8

9/64 TTSS

6/64 TtSS

9/64 ttSS

Ss – 2/8

6/64 TTSs

4/64 TtSs

6/64 ttSs

ss – 3/8

9/64 TTss

6/64 Ttss

9/64 ttss

9 TTSS:6 TTSs:9 TTss:6 TtSS:4 TsSs:6 Ttss:9 ttSS:6 ttSs:9 ttss 25 T_S_ : 15 T_ss : 15 ttS_ : 9 ttss

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

Ttss

1/16

2/16

1/16

2/16

4/16

2/16

1/16

2/16

1/16

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

Ttss

4/64

8/64

4/64

8/64

16/64

8/64

4/64

8/64

4/64

F3

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

ttss

4/64

8/64

4/64

8/64

16/64

8/64

4/64

8/64

4/64

TTSS

4

TTSs

-

TTss

-

TtSS

-

TtSs

-

Ttss

-

ttSS

-

ttSs

-

ttss

-

F3

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

ttss

4/64

8/64

4/64

8/64

16/64

8/64

4/64

8/64

4/64

TTSS

4

2

TTSs

-

4

TTss

-

2

TtSS

-

-

TtSs

-

-

Ttss

-

-

ttSS

-

-

ttSs

-

-

ttss

-

-

F3

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

ttss

4/64

8/64

4/64

8/64

16/64

8/64

4/64

8/64

4/64

TTSS

4

2

-

TTSs

-

4

-

TTss

-

2

4

TtSS

-

-

-

TtSs

-

-

-

Ttss

-

-

-

ttSS

-

-

-

ttSs

-

-

-

ttss

-

-

-

F3

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

ttss

4/64

8/64

4/64

8/64

16/64

8/64

4/64

8/64

4/64

TTSS

4

2

-

2

1

-

-

-

-

TTSs

-

4

-

-

2

-

-

-

-

TTss

-

2

4

-

1

2

-

-

-

TtSS

-

-

-

4

2

-

-

-

-

TtSs

-

-

-

-

4

-

-

-

-

Ttss

-

-

-

-

2

4

-

-

-

ttSS

-

-

-

2

1

-

4

2

-

ttSs

-

-

-

-

2

-

-

4

-

ttss

-

-

-

-

1

2

-

2

4

F3

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

ttss

4/64

8/64

4/64

8/64

16/64

8/64

4/64

8/64

4/64

TTSS

4

2

-

2

1

-

-

-

-

9

TTSs

-

4

-

-

2

-

-

-

-

6

TTss

-

2

4

-

1

2

-

-

-

9

TtSS

-

-

-

4

2

-

-

-

-

6

TtSs

-

-

-

-

4

-

-

-

-

4

Ttss

-

-

-

-

2

4

-

-

-

6

ttSS

-

-

-

2

1

-

4

2

-

9

ttSs

-

-

-

-

2

-

-

4

-

6

ttss

-

-

-

-

1

2

-

2

4

9

Total

F3

F2 TTSS

TTSs

TtSS

TtSs

4/64

8/64

8/64

16/64

TTSS

4

2

2

1

9

TTSs

-

4

-

2

6

TTss

-

2

-

1

3

TtSS

-

-

4

2

6

TtSs

-

-

-

4

4

Ttss

-

-

-

2

2

ttSS

-

-

2

1

3

ttSs

-

-

-

2

2

ttss

-

-

-

1

1

Total

F3

F2 TTSS

TTSs

TTss

TtSS

TtSs

Ttss

ttSS

ttSs

ttss

4/64

8/64

4/64

8/64

16/64

8/64

4/64

8/64

4/64

TTSS

-

-

0

TTSs

-

-

0

TTss

-

-

0

TtSS

-

-

0

TtSs

-

-

0

Ttss

-

-

0

ttSS

4

2

6

ttSs

-

4

4

ttss

-

2

2

Total

Selection Selection stage

Dominant Character

Recessive Character

1 trait

2 trait

1 trait

2 trait

F2

75%

56%

25%

6%

F3

63%

39%

37%

14%

F4

56%

32%

44%

19%

F

50%

25%

50%

25%

Mis-selection Selection stage

Dominant Character

1 trait

2 trait

F2

+33 % +55 % -33 %

-20 %

F3

+21 % +35 % -21 %

-13 %

F4

+11 % +22 % -11 %

-7 %

F

1 trait

0%

2 trait

Recessive Character

0%

0%

0%

Linkage (allelic interactions) & Epistasis (non-allelic interactions)