1. Help needed for the Art & Science Day at the Chester Street Elementary school 110 Chester St, Kingston
12- 3:30 on Tuesday, March 22.

2. Seeds
Seeds are unique feature of plants

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

4. 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

5. 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

6. 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

7. 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

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

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

10. Seeds
(Usually) required for fruit development!

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

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

13. 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

14. 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

15. 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

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

17. 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

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

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

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

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

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

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

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

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

26. 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!

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

28. 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

29. 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

30. 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!

31. 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

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

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

34. 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

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

36. 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

37. 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

38. 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

39. 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

40. 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

41. 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

42. 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

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

44. 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

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

46. 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

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

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

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

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

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

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

53. 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)

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

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

56. 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!

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

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

59. 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

60. 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

61. 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

62. 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

63. 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

64. Seed germination
Seeds remain dormant until sense appropriate conditions:
Many require light: says that they will soon be able to photosynthesize: often small seeds with few reserves
Hormones can also trigger (or stop) germination
ABA blocks it
GA stimulates it

65. Seed germination
Seeds remain dormant until sense appropriate conditions:
Many require light: says that they will soon be able to photosynthesize: often small seeds with few reserves
Hormones can also trigger (or stop) germination
ABA blocks it
GA stimulates it
Germination is a two step process
Imbibition

66. 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.

67. 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

68. 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

69. 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!

70. 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

71. 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

72. 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

73. 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

74. 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
ABA blocks

75. 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