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General Biological Concepts

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Presentation on theme: "General Biological Concepts"— Presentation transcript:

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

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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

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11 Plant Breeding 2009 Fall Chapter 2

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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

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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

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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

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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

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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

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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

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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

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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


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