1. Plant Growth & Development
3 stages
Embryogenesis
Fertilization to seed

2. Plant Growth & Development
3 stages
Embryogenesis
Fertilization to seed
2. Vegetative growth
Juvenile stage
Germination to adult

3. Plant Growth & Development
3 stages
Embryogenesis
Fertilization to seed
2. Vegetative growth
Juvenile stage
Germination to adult
"phase change" marks transition

4. Plant Growth & Development
3 stages
Embryogenesis
Fertilization to seed
2. Vegetative growth
Juvenile stage
Germination to adult
"phase change" marks transition
3. Reproductive development
Make flowers, can
reproduce sexually

5. Sexual reproduction
haploid gametogenesis in flowers: reproductive organs
Female part = pistil (gynoecium)
Stigma
Style
Ovary
Ovules

6. Sexual reproduction
haploid gametogenesis in flowers: reproductive organs
Female part = pistil (gynoecium)
Stigma
Style
Ovary
Ovules
Male part :
anthers
Make pollen

7. Primary sporogenous cells Primary parietal cells
Sexual reproduction
1. making haploid gametes in flowers
Pollen = male, 2-3 cells
Made in anther locules
(Wilson & Yang, 2004, Reproduction)
Archesporial cell
Primary sporogenous cells
Microspores
Pollen mother cells
Primary parietal cells
2o parietal cells
Endothecium
Tapetum
Middle cell layer
meiosis

8. Sexual reproduction
1. making haploid gametes in flowers
Pollen = male, contains 2-3 cells
Made in anthers
Microspores divide to form vegetative cell and germ cell

9. Sexual reproduction
1. making haploid gametes in flowers
Pollen = male, contains 2-3 cells
Made in anthers
Microspores divide to form vegetative cell and germ cell
Germ cell divides to form 2 sperm cells, but often not until it germinates

10. Sexual reproduction
1. making haploid gametes in flowers
Pollen = male, contains 2-3 cells
Made in anthers
Microspores divide to form vegetative cell and germ cell
Germ cell divides to form 2 sperm cells, but often not until it germinates
Pollen grains dehydrate and are coated

11. Sexual reproduction
1. making haploid gametes in flowers
Pollen = male, contains 2-3 cells
Made in anthers
Microspores divide to form vegetative cell and germ cell
Germ cell divides to form 2 sperm cells, but often not until it germinates
Pollen grains dehydrate and are coated
Are released, reach stigma, then germinate

12. Sexual reproduction
1. making haploid gametes in flowers
Pollen = male, contains 2-3 cells
Egg = female, made in ovaries

13. Sexual reproduction
1. making haploid gametes in flowers
Pollen = male, contains 2-3 cells
Egg = female, made in ovaries
Megaspore mother cell → meiosis → 4 haploid megaspores

14. Megaspore mother cell → meiosis → 4 haploid megaspores 3 die
Sexual reproduction
Megaspore mother cell → meiosis → 4 haploid megaspores
3 die
Functional megaspore divides 3 x w/o cytokinesis

15. Megaspore mother cell → meiosis → 4 haploid megaspores 3 die
Sexual reproduction
Megaspore mother cell → meiosis → 4 haploid megaspores
3 die
Functional megaspore divides 3 x w/o cytokinesis
Cellularization forms egg, binucleate central cell, 2 synergids & 3 antipodals

16. Egg, synergids & central cell are essential
Sexual reproduction
Cellularization forms egg, binucleate central cell, 2 synergids & 3 antipodals
Egg, synergids & central cell are essential

17. Egg, synergids & central cell are essential
Sexual reproduction
Cellularization forms egg, binucleate central cell, 2 synergids & 3 antipodals
Egg, synergids & central cell are essential
In many spp antipodals degenerate

18. Sexual reproduction
making haploid gametes in flowers
Pollen lands on stigma & germinates if good signals

19. Sexual reproduction
making haploid gametes in flowers
Pollen lands on stigma & germinates if good signals
Forms pollen tube that grows through style to ovule

20. Sexual reproduction
Pollen lands on stigma & germinates if good signals
Forms pollen tube that grows through style to ovule
Germ cell divides to form sperm nuclei

21. Sexual reproduction
Pollen lands on stigma &
germinates if good signals
Forms pollen tube that grows
through style to ovule
Germ cell divides to form sperm
nuclei
Pollen tube reaches micropyle
& releases sperm nuclei into ovule

22. Sexual reproduction
Pollen tube reaches micropyle
& releases sperm nuclei into ovule
Double fertilization occurs!

23. Sexual reproduction
Pollen tube reaches micropyle
& releases sperm nuclei into ovule
Double fertilization occurs!
One sperm fuses with egg
to form zygote

24. Sexual reproduction
Pollen tube reaches micropyle
& releases sperm nuclei into ovule
Double fertilization occurs!
One sperm fuses with egg
to form zygote
Other fuses with central cell to
form 3n endosperm

25. Sexual reproduction
Pollen tube reaches micropyle
& releases sperm nuclei into ovule
Double fertilization occurs!
One sperm fuses with egg
to form zygote
Other fuses with central cell to
form 3n endosperm
Synergids play key role in releasing
& guiding sperm cells

26. Embryogenesis
One sperm fuses with egg to form zygote
Other fuses with central cell to form 3n endosperm
Development starts immediately!

27. Embryogenesis
Cell division = growth
Determination = what cell can become
Differentiation = cells become specific types

28. Embryogenesis
Cell division = growth
Determination = what cell can become
Differentiation = cells become specific types
Pattern formation: developing specific structures in specific locations

29. Embryogenesis
Cell division = growth
Determination = what cell can become
Differentiation = cells become specific types
Pattern formation
Morphogenesis: organization into tissues & organs

30. Embryogenesis
Establishing polarity: 1st division
Establishing radial patterning: periclinal divisions form layers that become dermal, ground & vascular tissue
Forming the root and shoot meristems
Forming cotyledons & roots
Body plan is formed during embryogenesis: seedling that germinates is a juvenile plant with root and apical meristems

31. Seeds
Seeds are unique feature of plants

32. Seeds
Seeds are unique feature of plants
Plant dispersal units

33. Seeds
Seeds are unique feature of plants
Plant dispersal units
Must survive unfavorable
conditions until they reach
suitable place (and time) to
start next generation

34. Seeds
Seeds are unique feature of plants
Plant dispersal units
Must survive unfavorable conditions until they reach
suitable place (and time) to start next generation
Are dormant

35. Seeds
Seeds are unique feature of plants
Plant dispersal units
Must survive unfavorable conditions until they reach
suitable place (and time) to start next generation
Are dormant; dehydration is key

36. Seeds
Seeds are unique feature of plants
Plant dispersal units
Must survive unfavorable conditions until they reach
suitable place (and time) to start next generation
Are dormant; dehydration is key
Germinate when conditions are right

37. Seeds
Germinate when conditions are right
Need way to sense conditions while dormant

38. Seeds
Germinate when conditions are right
Need way to sense conditions while dormant
Need reserves to nourish seedling until it is established

39. Seeds
(Usually) required for fruit development!

40. Seeds
(Usually) required for fruit development!
Role of fruit is to aid seed dispersal!

41. Seed Development
(Usually) required for fruit development!
Role of fruit is to aid seed dispersal!
Unfertilized flowers don’t develop fruit

42. Seed Development
(Usually) required for fruit development!
Role of fruit is to aid seed dispersal!
Unfertilized flowers don’t develop fruits
The growth regulators GA, auxin or cytokinin can all induce parthenocarpy

43. Seed Development
(Usually) required for fruit development!
Role of fruit is to aid seed dispersal!
Unfertilized flowers don’t develop fruits
The growth regulators GA, auxin or cytokinin can all induce parthenocarpy
GA + auxin or GA + cytokinin work best

44. Seed Development
(Usually) required for fruit development!
Role of fruit is to aid seed dispersal!
Unfertilized flowers don’t develop fruits
The growth regulators GA, auxin or cytokinin can all induce parthenocarpy
GA + auxin or GA + cytokinin work best
Hormones from embryo stimulate fruit development

45. Seed Development
Hormones from embryo stimulate fruit development
Other floral organs make inhibitor that blocks fruit development until they abscise

46. Seed Development
Hormones from embryo stimulate fruit development
Other floral organs make inhibitor that blocks fruit development until they abscise
Divide seed development into three phases of ± equal time

47. Seed Development
Divide seed development into three phases of ± equal time
Morphogenesis

48. Seed Development
Divide seed development into three phases of ± equal time
Morphogenesis
Maturation

49. Seed Development
Divide seed development into three phases of ± equal time
Morphogenesis
Maturation
Dehydration and dormancy

50. Seed Development
End result is seed with embryo packaged inside protective coat

51. Seed Development
End result is seed with embryo packaged inside protective coat
Seed coat is maternal tissue!

52. Seed Development
End result is seed with embryo packaged inside protective coat
Seed coat is maternal tissue!
Derived from epidermal tissue surrounding ovule

53. Seed Development
Seed coat is maternal tissue!
Derived from epidermal tissue surrounding ovule
Determines shape of the seed!

54. Seed Development
Seed coat is maternal tissue!
Derived from epidermal tissue surrounding ovule
Determines shape of the seed!
Testa mutants have odd-shaped seeds

55. Seed Development
Seed coat is maternal tissue!
Derived from epidermal tissue surrounding ovule
Determines shape of the seed!
Testa mutants have odd-shaped seeds
embryo grows to fill shape set by testa!

56. Seed Development
End result is seed with embryo packaged inside protective coat
Endosperm feeds developing embryo (3n grows faster)

57. Seed Development
End result is seed with embryo packaged inside protective coat
Endosperm feeds developing embryo (3n grows faster)
In many dicots endosperm is absorbed as seed develops

58. Seed Development
End result is seed with embryo packaged inside protective coat
Endosperm feeds developing embryo (3n grows faster)
In many dicots endosperm is absorbed as seed develops
Often leave a thin layer of endosperm just inside testa

59. Seed Development
End result is seed with embryo packaged inside protective coat
Endosperm feeds developing embryo (3n grows faster)
In many dicots endosperm is absorbed as seed develops
Often leave a thin layer of endosperm just inside testa
Seeds have three different genetic compositions!

60. Seed Development
End result is seed with embryo packaged inside protective coat
Endosperm feeds developing embryo (3n grows faster)
In many dicots endosperm is absorbed as seed develops
In many monocots
endosperm is seedling food

61. Seed Development
Embryogenesis
Maturation: cell division ± ceases, but cells still expand

62. Seed Development
Embryogenesis
Maturation: cell division ± ceases, but cells still expand
Controlled by different genes: viviparous mutants have normal morphogenesis but don’t mature

63. Seed Development
Embryogenesis
Maturation: cell division ± ceases, but cells still expand
Controlled by different genes: viviparous mutants have normal morphogenesis but don’t mature
Many morphogenesis mutants show normal maturation

64. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds

65. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds
ABA made by maternal tissue initiates this process

66. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds
ABA made by maternal tissue initiates this process
Seed [ABA] increases as enter maturation phase

67. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds
ABA made by maternal tissue initiates this process
Seed [ABA] increases as enter maturation phase
Switch to ABA synthesis by embryo & endosperm during maturation

68. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds
Storage compounds are key for seedlings and crops

69. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds
Storage compounds are key for seedlings and crops
Proteins, lipids & carbohydrates but vary widely

70. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds
Storage compounds are key for seedlings and crops
Proteins, lipids & carbohydrates but vary widely
Many 2˚ metabolites

71. Seed Development
Maturation: cell division ± ceases, but cells still expand
Activate new genes for making storage compounds
Storage compounds are key for seedlings and crops
Proteins, lipids & carbohydrates but vary widely
Next prepare for desiccation as ABA made by embryo (+endosperm) increases

72. Seed Development
Next prepare for desiccation as ABA made by embryo (+endosperm) increases
ABA peaks at mid-maturation, then declines (but not to 0)

73. Seed Development
Next prepare for desiccation as ABA made by embryo (+endosperm) increases
ABA peaks at mid-maturation, then declines (but not to 0)
Blocks vivipary during maturation

74. Seed Development
Next prepare for desiccation as ABA made by embryo (+endosperm) increases
Make proteins & other molecules (eg trehalose) that help tolerate desiccation

75. Seed Development
Next prepare for desiccation as ABA made by embryo (+endosperm) increases
Make proteins & other molecules (eg trehalose) that help tolerate desiccation
Next dehydrate (to 5% moisture content) and go dormant

76. Seed Development
Next dehydrate (to 5% moisture content) and go dormant
Very complex: 2 classes of dormancy
Coat-imposed
embryo dormancy

77. Seed Development
Coat-imposed dormancy (maternal effect)
Preventing water uptake.

78. Seed Development
Coat-imposed dormancy (maternal effect)
Preventing water uptake.
Mechanical constraint

79. Seed Development
Coat-imposed dormancy (maternal effect)
Preventing water uptake.
Mechanical constraint
Interference with gas exchange.

80. Seed Development
Coat-imposed dormancy (maternal effect)
Preventing water uptake.
Mechanical constraint
Interference with gas exchange
Retaining inhibitors (ABA)

81. Seed Development
Coat-imposed dormancy (maternal effect)
Preventing water uptake.
Mechanical constraint
Interference with gas exchange
Retaining inhibitors (ABA)
Inhibitor production (ABA)

82. Seed Development
Coat-imposed dormancy (maternal effect)
Preventing water uptake.
Mechanical constraint
Interference with gas exchange
Retaining inhibitors (ABA)
Inhibitor production (ABA)
Embryo dormancy (Zygotic effect)

83. Seed Development
Coat-imposed dormancy (maternal effect)
Embryo dormancy (Zygotic effect)
Making inhibitors (ABA?)

84. Seed Development
Coat-imposed dormancy (maternal effect)
Embryo dormancy (Zygotic effect)
Making inhibitors (ABA?)
Absence of activators (GA)

85. Seed Development
Coordinated with fruit ripening: fruit’s job is to protect & disperse seed
Seeds remain dormant until sense appropriate conditions:
some Lotus germinated after 2000 years!

86. Seed germination
Seeds remain dormant until sense appropriate conditions:
some Lotus germinated after 2000 years!
Water

87. Seed germination
Seeds remain dormant until sense appropriate conditions:
some Lotus germinated after 2000 years!
Water
Temperature: some seeds require vernalization = prolonged cold spell

88. Seed germination
Seeds remain dormant until sense appropriate conditions:
some Lotus germinated after 2000 years!
Water
Temperature: some seeds require vernalization = prolonged cold spell
May break down hydrophobic seed coat

89. Seed germination
Seeds remain dormant until sense appropriate conditions:
Water
Temperature: some seeds require vernalization = prolonged cold spell
May break down hydrophobic seed coat
May allow inhibitor (eg ABA) to go away

90. Seed germination
Seeds remain dormant until sense appropriate conditions:
Water
Temperature: some seeds require vernalization = prolonged cold spell
May break down hydrophobic seed coat
May allow inhibitor (eg ABA) to go away
May allow synthesis of specific RNAs

91. Seed germination
Seeds remain dormant until sense appropriate conditions:
Water
Temperature: some seeds require vernalization = prolonged cold spell
May break down hydrophobic seed coat
May allow inhibitor (eg ABA) to go away
May allow synthesis of specific RNAs
Many require light: says photosynthesis is possible

92. Seed germination
Seeds remain dormant until sense appropriate conditions:
Water
Temperature: some seeds require vernalization = prolonged cold spell
Many require light: says photosynthesis is possible
often small seeds with few reserves

93. Seed germination
Seeds remain dormant until sense appropriate conditions:
Water
Temperature
Many require light
Some need acid treatment or scarification
Passage through bird gut
Some need fire

94. Seed germination
Seeds remain dormant until sense appropriate conditions:
Hormones can also trigger (or stop) germination
ABA blocks it
GA stimulates it

95. Seed germination
Seeds remain dormant until sense appropriate conditions:
Hormones can also trigger (or stop) germination
ABA blocks it
GA stimulates it
Germination is a two step process
Imbibition

96. Seed germination
Germination is a two step process
Imbibition is purely physical: seed swells as it absorbs water until testa pops.
Even dead seeds do it.

97. Seed germination
Germination is a two step process
Imbibition is purely physical: seed swells as it absorbs water until testa pops.
Even dead seeds do it.
Seeds with endosperm pop testa first, then endosperm

98. Seed germination
Germination is a two step process
Imbibition is purely physical: seed swells as it absorbs water until testa pops.
Even dead seeds do it.
Seeds with endosperm pop testa first, then endosperm
Separate processes: can pop testa but not endosperm

99. Seed germination
Germination is a two step process
Imbibition is purely physical: seed swells as it absorbs water until testa pops.
Even dead seeds do it.
Seeds with endosperm pop testa first, then endosperm
Separate processes: can pop testa but not endosperm
Testa and endosperm have different genotypes!

100. Seed germination
Germination is a two step process
Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it.
Seeds with endosperm pop testa first, then endosperm
Next embryo must start metabolism and cell elongation

101. Seed germination
Germination is a two step process
Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it.
Next embryo must start metabolism and cell elongation
This part is sensitive to the environment, esp T & pO2

102. Seed germination
Germination is a two step process
Next embryo must start metabolism and cell elongation
This part is sensitive to the environment, esp T & pO2
Hormones also play a complex role

103. Seed germination
Germination is a two step process
Next embryo must start metabolism and cell elongation
This part is sensitive to the environment, esp T & pO2
Hormones also play a complex role
GA, Ethylene and BR all stimulate

104. Seed germination
Hormones also play a complex role
GA, Ethylene and BR all stimulate
ABA blocks

105. Seed germination
Germination is a two step process
Next embryo must start metabolism and cell elongation
This part is sensitive to the environment, esp T & pO2
Once radicle has emerged, vegetative growth begins

106. Vegetative growth
Once radicle has emerged, vegetative growth begins
Juvenile plants in light undergo photomorphogenesis

107. Vegetative growth
Once radicle has emerged, vegetative growth begins
Juvenile plants in light undergo photomorphogenesis
Juvenile plants in dark undergo skotomorphogenesis
Seek light: elongate hypocotyl, don’t unfold cotyledons

108. Vegetative growth
Once radicle has emerged, vegetative growth begins
Juvenile plants in light undergo photomorphogenesis
Expand cotyledons, start making leaves & photosynthetic apparatus

109. Vegetative growth
Once radicle has emerged, vegetative growth begins
Juvenile plants in light undergo photomorphogenesis
Expand cotyledons, start making leaves & photosynthetic apparatus
Initially live off reserves, but soon do net photosynthesis