1. General Biological Concepts
Plant Breeding 2009 Fall
Chapter 2.
General Biological Concepts
The Art and Science of Plant Breeding
Plant Cellular Organization and Genetic Structure
Plant Reproductive systems
Chapter 2

2. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
1) Specific and permanent alteration in the plants
2) Heritable changes
3) Evolution, domestication, plant breeding
4) Plant breeding as an art
5) Plant breeding as a science
Chapter 2

3. Concept of evolution A population phenomenon (population evolves)
Plant Breeding 2009 Fall
Concept of evolution
A population phenomenon (population evolves)
Effect of changes in the frequency of alleles within a gene pool of a population
Evolution process (Darwin 1859, the theory of evolution)
- Variation (=diversity) in the initial pop. of organisms
- Environmental stresses place at a disadvantage
Individuals with best genetic fitness survive
These individuals leave more offspring in the next
generations
The population is dominated by these favored
individuals
Chapter 2

5. Plant Breeding 2009 Fall
Concept of evolution
The process of evolution has parallels in plant breeding
Three principles of plant breeding
Variation: Variation in morphology, physiology, and behavior exist among individuals in a natural population
Heredity: Offspring resemble their parents more than
they resemble unrelated individuals
3. Selection: Some individuals in a group are more capable of surviving and reproducing than others
Chapter 2

6. Concept of evolution Evolution
Plant Breeding 2009 Fall
Concept of evolution
Evolution
-> Variation by time (natural mutation, natural hybridization) and natural selection in long time,
Plant breeding
-> Variation by induced mutation or artificial hybridization and artificial selection in short time
Plant breeding = Direct or targeted and accelerated evolution
Chapter 2

7. Plant Breeding 2009 Fall
Domestication
Process by which genetic changes in wild plants are brought about through a selection process imposed by human
The results of domestication are plants that are adapted to supervised cultural conditions, and possessing characteristics that are preferred by producers and consumers.
Is domestication of the plant good for plant itself?
Chapter 2

11. Plant Breeding 2009 Fall
Chapter 2

13. Domestication Centers of plant domestication
Plant Breeding 2009 Fall
Domestication
Centers of plant domestication
= regions of genetic diversity, variability critical to the
success of crop improvement
= area where a crop plant originated and its wild
progenitor occurred from (De Candolle, 1886)
Center of diversity
= geographical area(s) where it exhibits maximum
diversity
= eight major centers of diversity (N. Vavilov, 1920s)
= Center of origin of a crop plant (N. Vavilov, 1920s)
Chapter 2

14. N. Vavilov’s Centers of plant domestication
중국 (상추, 대두, 순무)
인도 (오이, 망고, 벼, 동양 목화)
IIa. 인도차이나(바나나, 코코넛, 벼)
III. 중앙아시아 (아몬드, 마)
근동지역(알파파, 배추, 호밀)
지중해연안 (셀러리, 병아리콩)
이디오피아(커피, 기장, 수수)
남미, 중앙아메리카 (옥수수, 파파야, 목화)
볼리비아, 에콰도루, 페루(목화, 감자, 토마토)
VIIIa. 칠레 (감자)

15. III V IV I
VII II
IIa VI
VIII
VIIIa

17. Domestication Role call of domesticated plants
Plant Breeding 2009 Fall
Domestication
Role call of domesticated plants
230 crops belonging to 180 genera and 64 families, mainly Gramineae(Poaceae), Leguminoseae (Fabaceae), Cruciferae, and Solanaceae
Four general periods of domestication:
Ancient ( BC), Early ( BC), Late (AD ), Recent (after AD 1750)
Changes accompanying domestication
Domestication syndrome: changes in morphological and physiological traits occurred by selection during domestication (J.R. Harlan, textbook Table 2.1)
Chapter 2

18. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
• Early domesticators needed:
Experience + Intuition for selection
• Modern breeders need:
Experience + Intuition + Scientific Knowledge
• Art and the concept of the “breeder’s eye”
Early breeders depended primarily on intuition, skill, and judgment on their work
Selection = a process of informed “eye-balling to discriminate among variation (story on “Russet Burbank” potato)
Chapter 2

19. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
• Scientific disciplines and technologies of plant breeding
Science disciplines directly or closely associated
- Plant breeding
- Genetics
- Agronomy
- Cytogenetics
- Molecular Genetics
- Botany
- Plant Physiology
- Biochemistry
- Plant Pathology
- Entomology - Statistics - Tissue culture
Chapter 2

20. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
• An operational classification of technologies of plant
breeding
see textbook, Table 2.2 (important!)
• The plant breeder as a decision-maker
Specific decisions made in a breeding project
1) Breeding objectives
- economically viable or significantly social benefit
- close touch with crop producers and consumers
Chapter 2

21. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
2) Germplasm
- parents used in a cross should supply the gene(s) of
interest
- wildtype, breeding lines, elite germplasm (cultivars)
3) Breeding strategy
- choice of the most effective method and technique
- different strategy depending on certain situation,
crops, traits, etc.
4) Type of cultivar
- hybrid, synthetic, blend
Chapter 2

22. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
5) Market
- processing or fresh market
- uniformity in the plant production
6) Evaluation
- plant breeding is a number game
- the number of genotypes(plants) to keep or discard
- where to evaluate and how long
7) Cultivar Release
- climax of a breeding program
- stability analysis to select genotype to be released
- assigning a name, legal protection, etc
Chapter 2

23. 최초로 상업화 된 유전자변형작물은 토마토에서 나왔답니다 내 이름은 ‘플라브세브’. 미국 캘진회사에서 절 만들었어요
Plant Breeding 2009 Fall
최초로 상업화 된 유전자변형작물은 토마토에서 나왔답니다
내 이름은 ‘플라브세브’. 미국 캘진회사에서 절 만들었어요
내몸엔 에틸렌생성을 억제시키는 유전자가 삽입되어 있어 저장, 수송력이 매우 우수하지..
많이들 즐샴.~
Chapter 2

24. 근데, 아쉽게 나의 전성기는 곧 막을 내려
난 원래 케첩용 토마토라 어차피
어깨질거
저장성, 수송성이 별 중요치 않았거든

25. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
• Conducting plant breeding
Different approaches for different breeding programs based on the reproduction of the plant, the type cultivars to be released, and resources available
Basic approaches
1) Conventional approach
- traditional/classical breeding
- use of tried, proven, older tools
- hybridization for creating variability and selection
- readily accessible to breeders, easy to conduct
Chapter 2

26. 전통육종의 기본은 교잡 우리 결혼할래? 그래, 하지만 바람피다 들키면 죽어 !! 새로운 세대는 바로 교잡을 통해…
그리고 제일 똘똘한 놈만 계속 선발해 나가는 거지

27. 똑 같은 부모에게서 낳지만,
형제의 모습이 다른 이유?
바로 감수분열과정에 있지..
자세한건 몰라도 되고,
아무튼, 이러쿵, 저러쿵해서
요로쿵 된다는 말씀!

28. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
2) Unconventional approach
- use of cutting-edge technology for variability
- expensive to conduct
- recombinant DNA (rDNA) technology
- gene transfer across natural biological barriers
- molecular markers for advanced selection
But, remember that “the conventional method remains the workhorse for most parts of the plant breeding industry”
Chapter 2

29. 자, 코끼리를 냉장고 안에 넣는 방법은?
냉장고 문을 연다
코끼리를 넣는다.
냉장고 문을 닫는다.
그럼, 유전자변형작물을 만드는 방법은?
세균에서 유전자를 꺼낸다
식물세포에 집어넣는다
세포를 완전한 식물체로 키운다…

30. 유전자변형작물은 이렇게 만들어 지네. 음…. 디게 에럽다

31. 세균의 유전자를 가진 식물세포가 세포배양을 통해 이렇게 자라났어요 .. 완전히 성장한 유전자변형식물..
세균의 유전자를 가진 식물세포가 세포배양을 통해 이렇게 자라났어요 ..
완전히 성장한 유전자변형식물..
‘내몸엔 세균의 피가 흐르고 있어, 그리고 다른 식물은 전혀 가질수 없는 특징이 있지’
이젠 실험실에서 나와 이렇게 화분에 옯겨 왔어요
Chapter 1

32. Particle bombardment를 이용한 형질전환

33. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
• Overview of the basic steps in plant breeding
1) Objectives
- high yield, disease resistance, early maturity, lodging
resistance (producer’s stand point)
- high nutritional quality, enhanced processing quality
(consumer’s stand poin)
2) Germplasm
- assemble (collect, develop, and organize) the
germplasm (plant materials for initiating a breeding
program)
Chapter 2

34. The Art and Science of Plant Breeding
Plant Breeding 2009 Fall
The Art and Science of Plant Breeding
3) Selection
- discriminate among the variability to identify and
select individuals with desirable genotype to advance
and increase to develop potential new cultivars
4) Evaluation
- potential cultivars are evaluated in the field or
greenhouse (at different locations, in several years)
5) Certification and cultivar release
- seed certification process
- increase the experimental seed
- obtain approval for release from crop certifying
agency
Chapter 2

35. 2. Plant Cellular Organization and Genetic Structure: an overview
Plant Breeding 2009 Fall
2. Plant Cellular Organization and Genetic Structure: an overview
1) Plant cell structure, organization, and division
2) Mendelian concept
3) DNA structure and function
4) Phenotype and genotype
5) Genetic linkage
6) The role of plant structure and processes in breeding
Chapter 2

36. Units of organization of living things
Plant Breeding 2009 Fall
Units of organization of living things
Cell: fundamental unit of organization of living things
(Unicellular vs multicellular)
Cellular compartmentalization: membrane-bound nucleus and organelles (eukaryotes)
Cell as a selection unit in genetic engineering
Plant as selection unit in conventional breeding
Genetic engineering
Transferring foreign genes -> Selecting cells -> regenerating cells to full plants -> selecting plants
(Genetic engineering still requires Conventional
breeding tool!)
Chapter 2

37. 생물체를 구성하는 단위 전통 식물 육종가 분자 식물 육종가 식물체 (whole organism, system)
조직 (tissue)
세포 (cell)
세포 소기관 (organelle)
분자 (molecule)
전통 식물 육종가
(Conventional breeding)
분자 식물 육종가
(Molecular breeding)

38. Structure of plant cell and its function (Table 3.1)
Plant Breeding 2009 Fall
Plant Genome
Structure of plant cell and its function (Table 3.1)
Cell = nucleus + extranulear region (cytoplasm)
Plant organelles targeted for breeder = nucleus, mitochondria, chloroplast
why? because it’s associated with heredity
Genome: Gene + Chromosome, the set of chromosomes (or genes) within a gamete of a species (monoploid, haploid)
Genome = nuclear genome + organellar genome
Organellar genome = chloropast genome + mitochondrial genome
Chapter 2

40. Human chromosome set
2n = 2x = 46

41. Nuclear genome follows Medelian inheritance
Plant Breeding 2009 Fall
Plant Genome
Nuclear genome follows Medelian inheritance
Organellar genome follows Cytoplasmic inheritance
Some extranuclear genes are of special importance to plant breeding, like male sterility gene located in the mitochondria (CMS)
Why CMS?
->used to eliminate the need for emasculation (removing anthers before crossing or hybridization)
Gens carried in the maternal cytoplasm may influence the hybrid phenotype, called maternal effect
Chapter 2

42. Chromosomes and Nuclear Division
Plant Breeding 2009 Fall
Chromosomes and Nuclear Division
Chromosome: condensed DNA sequence in linear fashion as a visible strand at the stage of cell division
Two kinds of cells depending on chromosome number
Gametes (gametic cells) = half set of the chromosome
= haploid number (n)
Sometic cells = complete set of the chromosome = diploid number (2n)
Homologous chrom.: sometic chrom. arranged in pairs based on size, length, centromere position
Chapter 2

44. Chromosomes and Nuclear Division
Plant Breeding 2009 Fall
Chromosomes and Nuclear Division
In homologous chrom. one member of each pair is derived from the maternal parent (through egg) and the other from the paternal parent (through the pollen)
= biparental inheritance
-> as the result, each diploid cell contains two form of
each gene (allele)
Chapter 2

45. Introduction to Plant Breeding Lecture 1
Chromosome set in diploid
Introduction to Plant Breeding Lecture 1

46. 핵산(DNA)의 구조와 기능 DNA double helix Nucleosome Supercoil Metaphase
chromosome
Protein scaffold

47. Structure of DNA

48. Structure of DNA

49. Introduction to Plant Breeding Lecture 1
Central dogma - Overview
Introduction to Plant Breeding Lecture 1

50. Central dogma - Overview

51. Central dogma - DNA replication

52. Central dogma - Transcription: RNA synthesis

53. Gene constitution
Chromosome
Gene
mRNA

54. Central dogma - Translation: Genetic code & coding dictionary

55. Central dogma - Translation: Polypeptide synthesis
Transfer RNA (tRNA)

56. Translation: Formation of a peptide bond
Carboxyl group
Amino group
R group

57. Central dogma - Overview

58. Plant Cellular Organization and Genetic Structure
Central dogma - Gene expression
Plant Cellular Organization and Genetic Structure

59. Regulation of gene expression
1. 한 유전자가 그냥 발현된다는 것은 중요치 않다.
2. 한 유전자는, 올바른 시간에 올바른 만큼의 양으로 발현될 수 있도록 조절되어야 한다.
3. 발현 조절 물질(transcription factors)이 유전자(promoters)와 상호작용하여 그의 발현을 조절한다.
4. 유전자의 발현이 조절되는 단계들:
1) 전사, 2) RNA processing, 3) mRNA 수송, 4) mRNA 안정성, 5) 번역, 6) 단백질 활성

60. Chromosomes and Nuclear Division
Plant Breeding 2009 Fall
Chromosomes and Nuclear Division
Mitosis
Occurs only in somatic cell
Daughter cell contains the same no. of chromo. as mother cell (karyokinesis)
Products are genetically identical (equational division)
New cells for growth and maintenance of the plant
Meiosis
Occurs specialized tissues in flowers
Daughter cell contains the haploid no. of chromo.
Products are gametes or spores
Chapter 2

62. Introduction to Plant Breeding Lecture 1
Cell Cycle
Introduction to Plant Breeding Lecture 1

63. Plant Breeding 2009 Fall
Chapter 2

64. Plant Breeding 2009 Fall
Chapter 2

65. Plant Breeding 2009 Fall
Chapter 2

66. Plant Breeding 2009 Fall
Chapter 2

67. Plant Breeding 2009 Fall
Chapter 2

68. Plant Breeding 2009 Fall
Chapter 2

69. Plant Breeding 2009 Fall
Chapter 2

70. Plant Breeding 2009 Fall
Chapter 2

71. Plant Breeding 2009 Fall
Chapter 2

72. Plant Breeding 2009 Fall
Chapter 2

73. Plant Breeding 2009 Fall
Chapter 2

74. Plant Breeding 2009 Fall
Chapter 2

75. Plant Breeding 2009 Fall
Chapter 2

76. Chromosomes and Nuclear Division
Plant Breeding 2009 Fall
Chromosomes and Nuclear Division
Meiosis
A meiotic event, Crossing over, occurs resulting in genetic exchange between non-sister chromatids
Crossing over -> a major source of genetic variability
= responsible for new recombinations genetic materials
Genetic linkage? => very important for plant breeder
Maintenance of the ploidy level of the species
Chapter 2

77. Introduction to Plant Breeding Lecture 1
Meiosis
Introduction to Plant Breeding Lecture 1

78. Meiosis

79. Meiosis

80. Meiosis

81. Meiosis

82. Plant Breeding 2009 Fall
Chapter 2

85. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Mendel’s law of inheritance
Mendel’s contribution => discipline of genetics, principles of inheritance, transmission genetics
Result of Mendel’s study => traits are controlled by heritable factors that are from parents to offspring, through the reproductive cell
Dominance and Recessivity
Between two contrasting traits of the parents, the
expressed trait at hybrid(F1) is dominant and the
suppressed trait is recessive
Chapter 2

86. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Mendel’s law of inheritance
2. Law of segregation
Two factors that control each trait do not blend but
Remain distant throughout the life of the individual
and segregate in the formation of gametes
Paired factors segregate during the formation of
gametes in a random fashion such that each gamete
receives one form or the other
Chapter 2

87. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Mendel’s law of inheritance
3. Law of independent assortment
Genes (genetic factor) for different characters (traits)
are inherited independently of each other
When two or more pairs of traits are considered
simultaneously, the factors for each pair of traits assort
independently to the gametes
-Mendel’s pairs of factor => Genes
-Each factor of a pair => Allele
-Location of the gene on the chromosome => Locus
Chapter 2

88. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Concept of genotype and phenotype
Genotype = the totality of the genes of an individual
(in practice, a very small subset of genes of interest)
Genotype writing:
dominant allele -> A, recessive allele -> a
homozygous at this locus-> AA or aa
heterozygous at this locus -> Aa
A plant that has two identical(different) alleles for
genes is homozygous (heterozygous) at that locus, and
is called a homozygote (heterozygote)
Chapter 2

89. Locus, gene, allele, and genotype
Gene = locus
Gene = locus
Allele (A)
Allele (A)
Allele (a)
Allele (a)
Gene = locus
Mother
Allele (A)
Allele (a)
Father M F

90. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Concept of genotype and phenotype
Phenotype = observable effect of a genotype
= the result of the interaction between a genotype and
its environment
P (Phenotype) = G (Genotype) + E (Environment)
Chapter 2

92. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Predicting genotype and phenotype
Statistical probability analysis is applied to determine
the outcome of a cross, given the genotype of the
parents and gene action
Punnett square is used to facilitate the analysis
Distinghishing heterozygous and homozygous
Individuals
In a segregating population where genotypes PP and
Pp produce the same phenotype, Testcross or Progeny
test is conducted to know the exact genotype of the
plant
Chapter 2

93. ● The Punnett square method

94. Introduction to Plant Breeding Lecture 3
Testcross
Introduction to Plant Breeding Lecture 3

95. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Complex inheritance
How lucky was Mendel ?
Mendel’s traits = simply inherited traits (simple traits)
Complex traits = complex inheritance that cannot predicted by Mendelian ratio (non-Mendelian ratio)
Incomplete (partial) dominance:
masking of one trait by another is only partial
Red-flower (RR) X White-flower (rr) -> Pink flower (Rr)
Chapter 2

96. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Complex inheritance
Codominance: both alleles of a heterozygote are
expressed to equal degrees. Two alleles code for two equally functional and detectable gene products.
Multiple alleles of the same gene: The mode of
inheritance by which individuals have access to three or
more alleles to be created in a population
(ABO blood grop, Self-incompatibility (S) alleles)
Chapter 2

97. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Complex inheritance
Multiple genes: The same enzymes can be produced
by different genes = isozyme
Polygenic inheritance:
Mendelian genes = major genes -> easily categorized
into several or many non-overlapping groups = discrete
variation
Polygenes = minor genes -> some traits are controlled
by several or many genes that have effects too small to
be individually distinguished = non-discrete varation
Chapter 2

98. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Complex inheritance
Concept of gene interaction
The genetic influence on the phenotype is complex and
genes do not necessarily interact directly to influence a
Phenotype
The cellular function of numerous gene products work together in concert to produce the phenotype
Epistasis (interactions involving non-allelic genes)
9:7, 9:6:1, 15:1, 13:3, 12:3;1 etc (Fig. 3.8)
Chapter 2

99. 파리의 눈의 모양 변이

100. 피부의 색소 변이 (albinism)

101. RR pp
rr PP
Rr Pp
rr pp
닭의 벼루 모양 변이

102. 붓꽃의 색깔 변이 (Purple and white flowers of the sweet pea)

103. Bateson과 Punnett의 실험

104. Gene C P
Precursor Intermediate Anthocyanin
Genotype
C- ; P
cc ; P
C- ; pp

108. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Complex inheritance
Pleiotropy
A condition that multiple traits are affected by one gene
Chapter 2

109. Plant Cellular Organization and Genetic Structure
멜델의 유전법칙 (Mendel’s law)
Plant Cellular Organization and Genetic Structure
(a) dominance, (b) segregation, and (c) independent assortment

110. 다른 염색체상의 두 유전자의 독립적 분리 (independent assortment)

111. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Genetic linkage and its implication
Genetic linkage: the phenomenon whereby certain genes tend to be inherited together..
-> violates Mendel’s law of independent assortment
When genes are within a single chromosome and not assorted independently, they are said to be linked
and constitute a linkage group
-> the no. linkage group = haploid no. of chromosome
Chapter 2

112. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Genetic linkage and its implication
Complete linkage: gene A and B are inherited as if they were one gene (AABB, AaBb, aabb)
Incomplete linkage: crossover occurs between the gene A and B and cause some alteration in linkage
Recombinants (new genotype, like Aabb, aaBb…)
Recombinant frequency (RF): the proportion of recombinant gametes produced in meiosis in the multiple hybrid
Chapter 2

113. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Genetic linkage and its implication
Complete linkage: gene A and B are inherited as if they were one gene (AABB, AaBb, aabb)
Incomplete linkage: crossover occurs between the gene A and B and cause some alteration in linkage
Recombinants (new genotype, like Aabb, aaBb…)
Recombinant frequency (RF): the proportion of recombinant gametes produced in meiosis in the multiple hybrid (if two genes are completely linked, RF = 0)
Chapter 2

114. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Genetic linkage and its implication
Complete linkage: gene A and B are inherited as if they were one gene (AABB, AaBb, aabb)
Incomplete linkage: crossover occurs between the gene A and B and cause some alteration in linkage
Recombinants (new genotype, like Aabb, aaBb…)
Recombinant frequency (RF): the proportion of recombinant gametes produced in meiosis in the multiple hybrid (if two genes are completely linked, RF = 0)
Chapter 2

115. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Genetic linkage and its implication
Crossing-over during the meiosis causes recombination or shuffling of linked genes -> produce gamete with new genetic combination (unlike mother cell)
Genetic recombination is the most common source of variation in flowering species along with independent assortment of genes
Sometimes breeders want certain linkages left intact, when several desirable genes are tightly linked
Chapter 2

116. Mendelian Concepts in Plant Breeding
Plant Breeding 2009 Fall
Mendelian Concepts in Plant Breeding
Genetic linkage and
its implication
When a desirable gene
is linked to an undesirable
gene, breeders would like
to break the association
(linkage break)
Chapter 2

117. 유전적 연관 (Genetic linkage)
두유전자(A, B) 간의 유전적 거리가 짧을 경우, 서로 강하게 연관되어 있다고 하며, 교차가 일어나는 확률이 매우 낮음.
두유전자(A, B) 간의 유전적 거리가 긴 경우, 서로 약하게 연관되어 있다고 하며, 교차가 일어나는 확률이 높아짐.

118. 3. Plant Reproductive System
Plant Breeding 2009 Fall
3. Plant Reproductive System
1) Type of plant life cycles and their implication in breeding
2) Basic types of floral morphology
3) Mechanisms of pollination and fertilization
4) Breeding implications of self- and cross-pollination
5) Constraints to pollination and their implication in breeding
6) Genetics and applications of male sterility in breeding
Chapter 2

119. Importance of mode of reproduction to plant breeding
Plant Breeding 2009 Fall
Importance of mode of reproduction to plant breeding
Why breeders need to understand the mode of plant reproduction? Key reasons….
1. The genetic structure of plants depends on their
mode of reproduction
2. Artificial hybridization is needed to conduct genetic
studies to understand the inheritance of trait of
interest, and for transfer of genes of interest from one
parent to another
Chapter 2

120. Importance of mode of reproduction to plant breeding
Plant Breeding 2009 Fall
Importance of mode of reproduction to plant breeding
Why breeders need to understand the mode of plant reproduction? Key reasons….
3. Artificial hybridization requires an effective control of
pollination so that only the desired pollen is allowed to be involved in the cross
The mode of reproduction determines the procedures
for multiplication and maintenance of cultivars developed by plant breeder
Chapter 2

121. Overview of reproductive options in plant
Plant Breeding 2009 Fall
Overview of reproductive options in plant
Hermaphrodity versus unisexuality
Self-pollination versus cross-pollination
Self-fertilization versus cross-fertilization
Sexuality versus asexuality
Chapter 2

122. Overview of reproductive options in plant
Plant Breeding 2009 Fall
Overview of reproductive options in plant
1. Hermaphrodity versus unisexuality
Hermaphrodity: have both male and female sexual organs
-> self-fertilization is possible
-> promote a reduction in genetic variability
Chapter 2

123. Overview of reproductive options in plant
Plant Breeding 2009 Fall
Overview of reproductive options in plant
1. Hermaphrodity versus unisexuality
Unsexuality: have one kind of sexual organs
-> cross-fertilization is possible
-> promote genetic variability
Chapter 2

124. Overview of reproductive options in plant
Plant Breeding 2009 Fall
Overview of reproductive options in plant
Self-pollination versus cross-pollination
Self-pollination Cross-pollination
Chapter 2

125. Sexual reproduction of flowering plant
Plant Breeding 2009 Fall
Sexual reproduction of flowering plant
Sexual life cycle = alteration of generation
Two basic growth phases of flowering plant
1) Vegetative phase: plant produces vegetative growth only
2) Reproductive phase: plant produces flowers
The process of sexual reproduction
Meiosis: 2n (diploid) -> n (haploid)
= gametophyte generation phase
Fertilization: n (gamete) + n (gamete) -> 2n (zygote)
= sporophyte generation phase
Chapter 2

126. Alternation of generation in flowering plants

127. Sexual reproduction of flowering plant
Plant Breeding 2009 Fall
Sexual reproduction of flowering plant
Duration of plant growth cycles
Annuals
Biennials
Perennials
Monocarps
Types of flower
Complete flower (e.g., soybean, tomato, cotton, tobacco)
Incomplete flower (rice, wheat, corn)
Perfect flower (=bisexual, wheat, tomato, pepper)
4) Imperfect flower (staminate or pistilate flowers, cucumber)
Chapter 2

128. Four life cycles of flowering plant

129. Sexual reproduction of flowering plant
Plant Breeding 2009 Fall
Sexual reproduction of flowering plant
Types of flower
5) Monoecious plant (staminate and pistilate flower on the same plant, corn)
Dioecious plant (staminate and pistilate flower on the different plant, papya, asparagus)
Gametogenesis
In gametogenesis, gametes(n) are produced from specialized
diploid cells called microspore mother cells in anthers and
megaspore mother cells in the ovary to be united and
transformed into an embryo
Chapter 2

130. Four basic part of the typical flower
다양한 화기 구조
1. 완전화 (complete flower)와 불완전화 (incomplete flower)
2. 양성화(perfect flower)와 단성화(imperfect flower)
3. 자화(pistilate flower)와 웅화 (staminate flower)
4. 자웅동주 (monoecious plant)와 자웅이주 (dioecious plant)
5. 단화(solitary flower)와 화서(inflorescence)

131. Gametogenesis in Plant

132. Sexual reproduction of flowering plant
Plant Breeding 2009 Fall
Sexual reproduction of flowering plant
Pollination & Fertilization
1) Pollination: the transfer of pollen grains from the anther to the stigma of a flower
Fertilization: one of the sperms unites with the egg cell, and the other sperm cell unites with the two polar nuclei (triple fusion) = double fertilization
Self-pollination
Mechanism that promote self-pollination :
1) Cleistrogamy; the condition that the flowers open only after it has been pollinated (wheat, barley, lettuce)
Chapter 2

133. Sexual reproduction of flowering plant
Plant Breeding 2009 Fall
Sexual reproduction of flowering plant
Self-pollination
Genetic & breeding implication of self-pollination:
1) achieves a highest degree of inbreeding
2) promotes homozygosity of all gene loci and traits
= the genotypes of gametes of a single plant are all
the same
3) the progeny of a single plant is homogeneous
4) restricts the creation of new gene combination
5) Mutations are readily exposed through homozygosity
6) Specific breeding methods: pure-line selction, pedigree breeding, bulk population, and backcross breeding
Chapter 2

134. Sexual reproduction of flowering plant
Plant Breeding 2009 Fall
Sexual reproduction of flowering plant
Cross-pollination
Mechanism that promote cross-pollination :
1) Dioecy: a plant is either female or male but not hermaphrodite
2) Monoecy: receive pollen from their own male flowers
3) Dichogamy; in hermaphroditic flowers, the stamens mature before the pistil is mature and receptive (protandry) or the reverse (protogyny)
4) Self-incompatibility; the pollen from a flower is not tolerated by its own stigma
5) Male sterility; the pollen of male is sterile
6) Heterostyly; significant difference in the lengths of the stamen and pistil
Chapter 2

135. Sexual reproduction of flowering plant
Plant Breeding 2009 Fall
Sexual reproduction of flowering plant
Cross-pollination
Genetic & breeding implication of self-pollination:
1) Genotype of the sporophytic generation is heterozygous
2) Genotypes of gametes of a single plant are all different
3) New gene combinations are created in the next generation
4) When selfed, ‘Inbreeding depression’ occurs
5) Hybrid vigor is exploited in hybrid seed production
6) Usually population-based breeding methods; mass selection, reccurrent selection, synthetic cultivars
Chapter 2

136. Asexual reproduction Vegetative propagation
Plant Breeding 2009 Fall
Asexual reproduction
Vegetative propagation
Vegetative = bulbs, corms, rhizomes, stems, buds
Mechanism that promote cross-pollination :
1) Flowering and fertility is reduced
2) Numerous plantlets are generated from small piece if vegetative materials by using cutting, grafting, micropropagation (tissue culture)
3) potato, yam, cassava, sugarcane, and many fruit trees
Chapter 2

137. Asexual reproduction Vegetative propagation
Plant Breeding 2009 Fall
Asexual reproduction
Vegetative propagation
Genetic & breeding implication of vegetative propagation
1) Once a desirable genotype combination has been achieved, clonal cultivas can be released immediately following the cross.
2) Heterosis is fixed (maintained indefinitely) in the hybrid product
3) Clonal crops are perennial outcrossers and intolerant of inbreeding
4) General combining ability (GCA) and specific combining ability (SCA) can be fully exploited with appropriate breeding methods and population size
Chapter 2

138. Apomixis Ability to develop seed without fertilization
Plant Breeding 2009 Fall
Apomixis
Ability to develop seed without fertilization
Apomictically produced seeds are clones of the mother plant = apomixis is the asexual production of seed
Found from 10% of 400 plant families (Gramineae,
Compositae, Rosaeae, and Asteraceae) and 1% of 40,000
species (citrus, brerries, mango, perennial forage grasses)
Facultative apomixis: produce both sexual and apomitic seed
Obligate apomixis: produce only apomitic seeds
Chapter 2

139. Apomixis Indicators of apomitics Indicator of facultative apomitics:
Plant Breeding 2009 Fall
Apomixis
Indicators of apomitics
Indicator of facultative apomitics:
the progeny from a cross in a cross-pollinated species fails to segregate
2) Indicator of obligate apomitics:
multiple floral feature, multiple seedlings per seed,
the progeny of a cross shows a high number of
identical homozygous individuals that resemble the
mother plant in addition to the presence of
individuals that are clearly different
Chapter 2

140. Apomixis Benefits of apomixis:
Plant Breeding 2009 Fall
Apomixis
Benefits of apomixis:
1) A breeding tool to develop hybrids that can retain their original genetic properties indefinitely with repeated use
2) Breeders can use this tool to fix superior gene combination
3) No need to maintain and increase parental genotypes
4) No need for producers to purchase fresh hybrid seed each year
Chapter 2

141. Apomixis Mechanisms of apomixis 1) Apospory 2) Diplospory
Plant Breeding 2009 Fall
Apomixis
Mechanisms of apomixis
1) Apospory
2) Diplospory
3) Adventitious embryo
4) Parthenogenesis
Chapter 2

142. Constraints of sexual biology in plant breeding
Plant Breeding 2009 Fall
Constraints of sexual biology in plant breeding
Some constraints are exploited as hybrid breeding tool
Methods for controlling cross-pollination(crossing)
1) Mechanical control:
removing anthers from bisexual flowers to prevent
pollination (emasculation)
2) Chemical control;
chemical hybridizing agents (gametocides, male
steriliants, pollenocides, androcides)
3) Genetic control;
male sterility, self-incompetibility
Chapter 2

143. Onion flower….. How would you cross-pollinate this plant?

144. Constraints of sexual biology in plant breeding
Plant Breeding 2009 Fall
Constraints of sexual biology in plant breeding
Self-incompatibility
=>a condition in which the pollen from a flower is not receptive on the stigma of the same flower and hence is incapable of setting seed
Heteromorphic incompatibility (Heterostyly)
Homomorphic incompatibility
a) Gametophytic incompatibility; the ability of the pollen
to function is determined by its own genotype and not
the plant that produces it
b) Sporophytic incompatibility; the incompatibility
characteristics of pollen are determined by the plant
that produce it
Chapter 2

145. 이형예 현상(Heterostyly) ss Ss 1. ss x ss = 불임 (sterile)
Genotype
Genotype ss Ss
1. ss x ss = 불임 (sterile)
2. Ss x Ss = 불임 (sterile)
3. ss x Ss = 임 (fertile)
4. Ss x ss = 임 (fertile)

146. 자가 불화합성 (Self-incompatibility)
2) 아포체 불화합성 (Sporophytic incompatibility)
1) 배우자 불화합성 (Gametophytic incompatibility)
가) Pollen을 생성하는 sporophyte의 genotype에 의해
임성/불임성이 결정
나) Sporophyte은 diploid로서 dominance 관계가 성립
다) S allele에 대한 homozygote도 형성될 수 있음
라) Stigma 상에서 pollen tube 성장이 저해 됨
가) pollen의 genotype에 의해 임성/불임성이 결정
나) pollen은 haploid이며 dominance가 성립치 않음
다) S allele에 대한 heterozygote만 형성 됨
라) Style 내에서 pollen tube의 생장이 저해 됨

147. Application of self-
incompatibility in practical
plant breeding

148. Constraints of sexual biology in plant breeding
Plant Breeding 2009 Fall
Constraints of sexual biology in plant breeding
Male sterility
=>a condition in plants whereby the anther or pollen are non-function
Genetic (nuclear, genic) male sterility
Cytoplasmic (mitocondrial gene) male sterility
Cytoplasmic-genic sterility
Chapter 2

149. Male sterility observed in the anther of rice flower
fertile
sterile
Pollens
Anther

150. Constraints of sexual biology in plant breeding
Plant Breeding 2009 Fall
Constraints of sexual biology in plant breeding
Genetic Male sterility
controlled by a single recessive nuclear gene, ms
genetically male-sterile types => msms
A pure population of genetic male-sterile plants can not be produced
Male-sterile genes may be carried along at a high frequency in a self-pollinate crop if seeds from the male-sterile plants only are harvested and used to plant next generation
Chapter 2

151. Genetic male sterility as used in practical breeding

152. Constraints of sexual biology in plant breeding
Plant Breeding 2009 Fall
Constraints of sexual biology in plant breeding
Cytoplasmic Male sterility (CMS)
Controlled by cytoplasm (mitochondrial gene)
A cytoplasm without sterility gene = normal (N) cytoplasm
A cytoplasm that cause male sterility = a sterile (s)
cytoplasm or said to have cytoplasmic male sterility (CMS)
CMS is transmitted through the egg (female plant=
maternal factor)
Fertility is restored by dominant fertility-restoring genes
transmitted through the pollen gametes
The pollen parent may have either CMS or normal
cytoplasm
Chapter 2

153. Maize tassel phenotype
Fertile male flowers
Sterile male flowers

154. Onion flower phenotype
Fertile anther
Sterile anther

155. Cytoplasmic male sterility

156. Constraints of sexual biology in plant breeding
Plant Breeding 2009 Fall
Constraints of sexual biology in plant breeding
Cytoplasmic-genetic Male sterility (CMS)
Fertility is restored by dominant fertility-restoring genes
transmitted through the pollen gametes
The pollen parent may have either CMS or normal
cytoplasm
Utilization in a breeding program
1) Eliminate emasculation in hybridization
2) Increase natural cross-pollination in self-pollinated crops
3) Facilitate commercial hybrid seed production
Chapter 2

157. The three systems of
cytoplasmic male sterility:
The teree factors involved
in CMS are the normal
cytoplasm, the male-sterile
cytoplasm, and the fertility
restorer (Rf, rf)

158. 웅성 불임성 (Male sterility)
Male-fertile
Msms
Male-sterile
1) 유전자적 웅성 불임성 (Genic male sterility)
MsMs
가) 핵 내 단일 열성 유전자(ms)에 의해 조절
다) genotype이 MsMs 또는 Msms일 경우 임성
다) genotype이 msms일 경우 불임성
msms X
Msms
Msms
msms
2) 세포질적 웅성 불임성 (Cytoplasmic male sterility,
CMS)
Male-sterile
Male-fertile
가) 세포질에 의해 조절되는 웅성불임성
나) 미토톤드리아 내 불임성 유전자(CMS)가 관여
다) 세포질 유전자는 난세포(egg)를 통해서만 후대전이 S X N S
Male-fertile
Rf rf S N or S
3) 세포질-유전자적 웅성 불임성 (Cytoplasmic-genic
male sterility)
Male-sterile
Rf Rf
가) 세포질 웅성 불임개체가 핵 내 유전자(Fertility-restoring, Rf)에 의해 임성을 되찾음.
나) 임성회복 유전자(Rf)는 핵 내 단일 우성인자
다) Rf 유전자는 CMS 유전자에도 우성으로 작용
rf rf S X
Rf rf S N or S
Rf rf
rf rf S