biparental mating design
TRANSCRIPT
Biparental Mating
Lokesh Gour
DEPARTMENT OF PLANT BREEDING & GENETICS JAWAHARLAL NEHRU KRISHI VISHWA VIDYALAYA
JABALPUR , MADHYA PRADESH (INDIA)
Guided by:-Dr. S.K. Singh, Assistant Professor
IntroductionComstock R.E. and Robinson H.F. (1948,1952)
Commonly F2 generation of pure lines strains are selected and crossed
in definite fashion
The paper of them were been cited in over 105 publications since 1961.
Three deigns of biparental
mating
☺ It involves F2, P1 and P2 generations of a single cross.
☺ It requires 3 crop season for generating material and fourth season for
evaluation
☺ It provides information about additive and dominance components of
genetic variance
☺ It helps in choice of breeding procedure for genetic improvement of
polygenic characters
☺ Analysis is based on second order statistics
Characteristics
Genetical assumptions of biparental cross
Random distribution of genotypes in relation to variation
Random choice of plants for mating
Regular diploid segregation
Absence of epistasis
Absence of linkage
Equal survival of all genotypes
Absence of maternal effects
Lack of multiple allelismAll these assumptions are seldom fulfilled
North Carolina Design 1
North Carolina Design 2
North Carolina Design 3
Biparental Mating
Nested Design&
Hierarchical design
Factorial Design
-
Material used for Biparental Mating
Population Parent 1
Parent 2
F2
Progenies
Half sib (male group)
Full sib (females/males)
Steps of biparental mating
1. Selection of parents Hmm !!!Having
contrasting characters
2. Making Original Cross
F1 seed
P1 P2
3. Growing F1 and F2 Progeny
F2 seed
F1 F1
4. Making Cross in F2
F2 Population now crossing done in definite fashion
F2 Seed
5. Evaluation of Crosses
Replicated Trial For
Observations
Randomly selecting
6. Biometrical Analysis
Computation of Sum of Squares
Genetical Interpretations
Analysis of Variance (ANOVA)
Component of Variances
Crossing Pattern
Nested Design
Males Females
3
4
910
1112
1314
1516
Males Females
1
2
12
34
56
78
Factorial Design
Males Females
F1 F2 F3 F4
M1 X X X X
M2 X X X X
M3 X X X X
M4 X X X x
North Carolina Design 3
Males Females
P1 P2
Set I
M1 X X
M2 X X
M3 X X
M4 X X
Set II
M5 X X
M6 X X
M7 X X
M8 X X
Variances analysed in NCD
The variance among single crosses is divided into
Two fractions
Three fractions
Two fractions
(i) Variance among males - which is equal to ¼ VA(ii) Variance due to females – which is equal to ¼ VA + ¼ VD
(i) Variance due males - equals to ¼ VA(ii) Variance due to females - equals to ¼ VA (iii) Variance due to male x female - equals to ¼ VD
(i) Variance among males - equals to ½ VA(ii) Variance due to male x female - equals to ½ VD
Evaluated Features of NCD Design
1. Each male is mated to a different set of females2. Equal to the number of females used in set x number of
sets3. Total number of crosses is equal to ns4. Presence of maternal effect
1. Each male is mated to the same set of females 2. Total number of cross is equal to mf3. Evaluation is equal to mns4. Presence of maternal effect
1. Each male is mated to the same set of females2. Each sat consists of 2m crosses3. Evaluation is equal to 2ns4. Absence of maternal effect
NCD I
NCD II
NCD III
Resulting Features of NCD Design
1. Maternal effect
NCD I NCD II NCD III
?
2. Area requirement
NCD I
NCD II
NCD III
More
Medium
Least
Use of North Carolina Design
1. Effective in breaking undesirable linkages- mating randomly selected
plants in segregating population
2. Selection of suitable breeding procedure- for polygenic characters
3. Can be used for self as well as cross pollinated species
4. Creation of variability- creating heterozygosity
5. Biparental mating permits evaluation of segregating (F2 or later
generation) population of an individual cross made between two inbred
lines
6. It provides information about two components of genetic variance i.e
additive and dominance variance
7. This technique helps in the selection of suitable breeding procedures
Problems of North Carolina Design
1. Not applicable to the segregating populations of three way, double and multiple
crosses
2. Not permit several segregating crosses simultaneously
3. Does not provide information about the epistatic variance
4. Analysis is difficult as it based on second order statistics
Comparison of biparental designs
S.NO NCD 1 NCD 2 NCD 3
1. Each male is mated to a different group of females
Each male is mated to a same group of females
Each male is mated to both inbred parents of original cross.
2. ‘f’ crosses were obtained ‘mf’ crosses were obtained ‘2m’crosses were obtained
3. Variance is divided into 2 fractions , due to males and due to females.
Variance is divided into 3 fractions, due to males, due to females and due to male x female
Variance is divided into 2 fractions due to male and due to male x female
4. Variance due to male provide an estimate of additive variance (D)
Variance due to male and female provide an esimate of additive variance (D)
Variance due to male provide an estimate of additive variance (D)
5. Variance due to female provide an estimate of additive (D) and dominance variance (H)
Variance due male x female provide an estimate of dominance variance (H)
Variance due to male x female provide an estimate of dominance variance(H)
NCD 1 NCD 2 NCD 3
6. Requires 10 – 12 times more area than design 3.
Requires 2-4 times more area than design 3.
Requires much less area than design 1 and 2.
7. Influenced by the presence of maternal effects.
Influenced by the presence of maternal effects.
Not affected by the presence of maternal effects.
8 Involves F2 Plants in crossing
Involves F2 Plants in crossing
Involves F2, P1 and P2 Plants in crossing
9. This is least powerful design
This is intermediate design This is most powerful design