1. LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick Angiosperm Reproduction and Biotechnology Chapter 38

2. Big Ideas  2.E.1) Timing and coordination of specific events are necessary for the normal development of an organism…  2.E.2) Timing and coordination of physiological events are regulated by multiple mechanisms. © 2011 Pearson Education, Inc. Illustrative Examples Illustrative Examples: Germination is triggered by water availability Flower development & pollination

3. Big Ideas 3.A: DNA, and in some cases, RNA is the primary heritable information. © 2011 Pearson Education, Inc. Illustrative Examples Illustrative Examples: Double fertilization  seed, endosperm

4. Beyond the Scope of the AP Exam…  Memorizing steps of any specific plant reproductive cycle, however general knowledge of the alternation of generations (sporophyte v. gametophyte) is fair game. See Figures 38. 2-3 © 2011 Pearson Education, Inc.

5. Overview: Flowers of Deceit Insects help angiosperms to reproduce sexually with distant members of their own species –For example, male Campsoscolia wasps mistake Ophrys flowers for females and attempt to mate with them –The flower is pollinated in the process –Unusually, the flower does not produce nectar and the male receives no benefit Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2011 Pearson Education, Inc.

6. Figure 38.1

7. Many angiosperms lure insects with nectar; both plant and pollinator benefit Mutualistic symbioses are common between plants and other species Angiosperms can reproduce sexually and asexually Angiosperms are the most important group of plants in terrestrial ecosystems and in agriculture Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2011 Pearson Education, Inc.

8. Concept 38.1: Flowers, double fertilization, and fruits are unique features of the angiosperm life cycle Plant lifecycles are characterized by the alternation between a multicellular haploid (n) generation and a multicellular diploid (2n) generation Diploid sporophytes (2n) produce spores (n) by meiosis; these grow into haploid gametophytes (n) Gametophytes produce haploid gametes (n) by mitosis; fertilization of gametes produces a sporophyte © 2011 Pearson Education, Inc.

9. In angiosperms, the sporophyte is the dominant generation, the large plant that we see The gametophytes are reduced in size and depend on the sporophyte for nutrients The angiosperm life cycle is characterized by “three Fs”: flowers, double fertilization, and fruits © 2011 Pearson Education, Inc.

10. Figure 38.2 Stamen Anther Filament Petal Receptacle Stigma Style Ovary Carpel Sepal (a) Structure of an idealized flower Simplified angiosperm life cycle (b) Key Haploid (n) Diploid (2n) Anther Pollen tube Germinated pollen grain (n) (male gametophyte) Ovary Ovule Embryo sac (n) (female gametophyte) Egg (n) Sperm (n) FERTILIZATION Zygote (2n) Mature sporophyte plant (2n) Germinating seed Seed Simple fruit Embryo (2n) (sporophyte)

11. Figure 38.2a Stamen Anther Filament Petal Receptacle Stigma Style Ovary Carpel Sepal (a) Structure of an idealized flower

12. Figure 38.2b Simplified angiosperm life cycle (b) Key Haploid (n) Diploid (2n) Anther Pollen tube Germinated pollen grain (n) (male gametophyte) Ovary Ovule Embryo sac (n) (female gametophyte) Egg (n) Sperm (n) FERTILIZATION Zygote (2n) Mature sporophyte plant (2n) Germinating seed Seed Simple fruit Embryo (2n) (sporophyte)

13. Flower Structure and Function Flowers are the reproductive shoots of the angiosperm sporophyte; they attach to a part of the stem called the receptacle Flowers consist of four floral organs: sepals, petals, stamens, and carpels Stamens and carpels are reproductive organs; sepals and petals are sterile © 2011 Pearson Education, Inc.

14. A stamen consists of a filament topped by an anther with pollen sacs that produce pollen A carpel has a long style with a stigma on which pollen may land At the base of the style is an ovary containing one or more ovules A single carpel or group of fused carpels is called a pistil © 2011 Pearson Education, Inc.

15. Complete flowers contain all four floral organs Incomplete flowers lack one or more floral organs, for example stamens or carpels Clusters of flowers are called inflorescences © 2011 Pearson Education, Inc.

16. Development of Male Gametophytes in Pollen Grains Pollen develops from microspores within the microsporangia, or pollen sacs, of anthers Each microspore undergoes mitosis to produce two cells: the generative cell and the tube cell A pollen grain consists of the two-celled male gametophyte and the spore wall © 2011 Pearson Education, Inc.

17. If pollination succeeds, a pollen grain produces a pollen tube that grows down into the ovary and discharges two sperm cells near the embryo sac © 2011 Pearson Education, Inc.

18. Development of a male gametophyte (in pollen grain) (a) Microsporangium (pollen sac) (b)Development of a female gametophyte (embryo sac) Microsporocyte Microspores (4) Each of 4 microspores Generative cell (will form 2 sperm) (LM) 75  m 20  m 100  m MEIOSIS MITOSIS Male gametophyte (in pollen grain) Nucleus of tube cell Ragweed pollen grain (colorized SEM) Key to labels Haploid (n) Diploid (2n) (LM) Embryo sac Ovule Megasporangium Megasporocyte Integuments Micropyle Surviving megaspore Antipodal cells (3) Polar nuclei (2) Egg (1) Synergids (2) Ovule Integuments Female gametophyte (embryo sac) Figure 38.3

19. Development of a male gametophyte (in pollen grain) (a) Microsporangium (pollen sac) Microsporocyte Microspores (4) Each of 4 microspores Generative cell (will form 2 sperm) (LM) 75  m 20  m MEIOSIS MITOSIS Male gametophyte (in pollen grain) Nucleus of tube cell Ragweed pollen grain (colorized SEM) Key to labels Haploid (n) Diploid (2n) Figure 38.3a

20. Development of Female Gametophytes (Embryo Sacs) The embryo sac, or female gametophyte, develops within the ovule Within an ovule, two integuments surround a megasporangium One cell in the megasporangium undergoes meiosis, producing four megaspores, only one of which survives The megaspore divides, producing a large cell with eight nuclei © 2011 Pearson Education, Inc.

21. This cell is partitioned into a multicellular female gametophyte, the embryo sac © 2011 Pearson Education, Inc.

22. Figure 38.3b (b) Development of a female gametophyte (embryo sac) 100  m MEIOSIS MITOSIS Key to labels Haploid (n) Diploid (2n) (LM) Embryo sac Ovule Megasporangium Megasporocyte Integuments Micropyle Surviving megaspore Antipodal cells (3) Polar nuclei (2) Egg (1) Synergids (2) Ovule Integuments Female gametophyte (embryo sac)

23. Pollination In angiosperms, pollination is the transfer of pollen from an anther to a stigma Pollination can be by wind, water, or animals Wind-pollinated species (e.g., grasses and many trees) release large amounts of pollen © 2011 Pearson Education, Inc.

24. Abiotic Pollination by Wind Pollination by Bees Hazel staminate flowers (stamens only) Hazel carpellate flower (carpels only) Common dandelion under normal light Common dandelion under ultraviolet light Figure 38.4a

25. Pollination by Moths and Butterflies Blowfly on carrion flower Pollination by Flies Pollination by Bats Moth on yucca flower Long-nosed bat feeding on cactus flower at night Hummingbird drinking nectar of columbine flower Pollination by Birds Stigma Anther Moth Fly egg Figure 38.4b

26. Coevolution of Flower and Pollinator Coevolution is the evolution of interacting species in response to changes in each other Many flowering plants have coevolved with specific pollinators The shapes and sizes of flowers often correspond to the pollen transporting parts of their animal pollinators –For example, Darwin correctly predicted a moth with a 28 cm long tongue based on the morphology of a particular flower © 2011 Pearson Education, Inc.

27. Figure 38.5

28. Double Fertilization After landing on a receptive stigma, a pollen grain produces a pollen tube that extends between the cells of the style toward the ovary Double fertilization results from the discharge of two sperm from the pollen tube into the embryo sac One sperm fertilizes the egg, and the other combines with the polar nuclei, giving rise to the triploid food-storing endosperm (3n) © 2011 Pearson Education, Inc.

29. Animation: Plant Fertilization Right-click slide / select “Play”

30. Figure 38.6-1 Stigma Pollen tube 1 2 sperm Style Ovary Ovule Micropyle Pollen grain Polar nuclei Egg

31. Figure 38.6-2 Stigma Pollen tube 21 2 sperm Style Ovary Ovule Micropyle Pollen grain Polar nuclei Egg Ovule Polar nuclei Egg Synergid 2 sperm

32. Figure 38.6-3 Stigma Pollen tube 231 2 sperm Style Ovary Ovule Micropyle Pollen grain Polar nuclei Egg Ovule Polar nuclei Egg Synergid 2 sperm Endosperm nucleus (3n) (2 polar nuclei plus sperm) Zygote (2n)

33. Seed Development, Form, and Function After double fertilization, each ovule develops into a seed The ovary develops into a fruit enclosing the seed(s) © 2011 Pearson Education, Inc.

34. Endosperm Development Endosperm development usually precedes embryo development In most monocots and some eudicots, endosperm stores nutrients that can be used by the seedling In other eudicots, the food reserves of the endosperm are exported to the cotyledons © 2011 Pearson Education, Inc.

35. Embryo Development The first mitotic division of the zygote splits the fertilized egg into a basal cell and a terminal cell The basal cell produces a multicellular suspensor, which anchors the embryo to the parent plant The terminal cell gives rise to most of the embryo The cotyledons form and the embryo elongates © 2011 Pearson Education, Inc.

36. Animation: Seed Development Right-click slide / select “Play”

37. Figure 38.7 Ovule Endosperm nucleus Integuments Zygote Terminal cell Basal cell Proembryo Suspensor Basal cell Cotyledons Shoot apex Root apex Suspensor Seed coat Endosperm

38. Ovule Endosperm nucleus Integuments Zygote Terminal cell Basal cell Figure 38.7a

39. Figure 38.7b Proembryo Suspensor Basal cell Cotyledons Shoot apex Root apex Suspensor Seed coat Endosperm

40. Structure of the Mature Seed The embryo and its food supply are enclosed by a hard, protective seed coat The seed enters a state of dormancy A mature seed is only about 5–15% water © 2011 Pearson Education, Inc.

41. In some eudicots, such as the common garden bean, the embryo consists of the embryonic axis attached to two thick cotyledons (seed leaves) Below the cotyledons the embryonic axis is called the hypocotyl and terminates in the radicle (embryonic root); above the cotyledons it is called the epicotyl The plumule comprises the epicotyl, young leaves, and shoot apical meristem © 2011 Pearson Education, Inc.

42. Figure 38.8 Seed coat Radicle Epicotyl Hypocotyl Cotyledons (a) Common garden bean, a eudicot with thick cotyledons (b) Castor bean, a eudicot with thin cotyledons (c) Maize, a monocot Seed coat Endosperm Cotyledons Epicotyl Hypocotyl Radicle Hypocotyl Epicotyl Endosperm Pericarp fused with seed coat Scutellum (cotyledon) Coleoptile Coleorhiza

43. Figure 38.8a Seed coat Radicle Epicotyl Hypocotyl Cotyledons (a) Common garden bean, a eudicot with thick cotyledons

44. The seeds of some eudicots, such as castor beans, have thin cotyledons © 2011 Pearson Education, Inc.

45. Figure 38.8b (b) Castor bean, a eudicot with thin cotyledons Seed coat Endosperm Cotyledons Epicotyl Hypocotyl Radicle

46. A monocot embryo has one cotyledon Grasses, such as maize and wheat, have a special cotyledon called a scutellum Two sheathes enclose the embryo of a grass seed: a coleoptile covering the young shoot and a coleorhiza covering the young root © 2011 Pearson Education, Inc.

47. Figure 38.8c (c) Maize, a monocot Radicle Hypocotyl Epicotyl Endosperm Pericarp fused with seed coat Scutellum (cotyledon) Coleoptile Coleorhiza

48. Seed Dormancy: An Adaptation for Tough Times Seed dormancy increases the chances that germination will occur at a time and place most advantageous to the seedling The breaking of seed dormancy often requires environmental cues, such as temperature or lighting changes © 2011 Pearson Education, Inc.

49. Seed Germination and Seedling Development Germination depends on imbibition, the uptake of water due to low water potential of the dry seed The radicle (embryonic root) emerges first Next, the shoot tip breaks through the soil surface © 2011 Pearson Education, Inc.

50. In many eudicots, a hook forms in the hypocotyl, and growth pushes the hook above ground Light causes the hook to straighten and pull the cotyledons and shoot tip up © 2011 Pearson Education, Inc.

51. Figure 38.9 Foliage leaves Cotyledon Hypocotyl Cotyledon Hypocotyl Radicle Seed coat Epicotyl Cotyledon Hypocotyl (a) Common garden bean Foliage leaves Coleoptile Radicle (b) Maize

52. Figure 38.9a Foliage leaves Cotyledon Hypocotyl Cotyledon Hypocotyl Radicle Seed coat Epicotyl Cotyledon Hypocotyl (a) Common garden bean

53. In maize and other grasses, which are monocots, the coleoptile pushes up through the soil © 2011 Pearson Education, Inc.

54. Figure 38.9b Foliage leaves Coleoptile Radicle (b) Maize

55. Fruit Form and Function A fruit develops from the ovary It protects the enclosed seeds and aids in seed dispersal by wind or animals A fruit may be classified as dry, if the ovary dries out at maturity, or fleshy, if the ovary becomes thick, soft, and sweet at maturity © 2011 Pearson Education, Inc.

56. Animation: Fruit Development Right-click slide / select “Play”

57. Fruits are also classified by their development –Simple, a single or several fused carpels –Aggregate, a single flower with multiple separate carpels –Multiple, a group of flowers called an inflorescence © 2011 Pearson Education, Inc.

58. Figure 38.10 Stamen Ovary Stigma Ovule Pea flower Seed Pea fruit (a) Simple fruit (b) Aggregate fruit (c) Multiple fruit (d) Accessory fruit Carpels Stamen Raspberry flower Carpel (fruitlet) Stigma Ovary Stamen Raspberry fruit Flower Pineapple inflorescence Each segment develops from the carpel of one flower Pineapple fruit Stigma Petal Style Stamen Sepal Ovule Ovary (in receptacle) Apple flower Remains of stamens and styles Sepals Seed Receptacle Apple fruit

59. Figure 38.10a Stamen Ovary Stigma Ovule Pea flower Seed Pea fruit (a) Simple fruit (b) Aggregate fruit Carpels Stamen Raspberry flower Carpel (fruitlet) Stigma Ovary Stamen Raspberry fruit

60. Figure 38.10b (c) Multiple fruit (d) Accessory fruit Flower Pineapple inflorescence Each segment develops from the carpel of one flower Pineapple fruit Stigma Petal Style Stamen Sepal Ovule Ovary (in receptacle) Apple flower Remains of stamens and styles Sepals Seed Receptacle Apple fruit

61. An accessory fruit contains other floral parts in addition to ovaries © 2011 Pearson Education, Inc.

62. Fruit dispersal mechanisms include –Water –Wind –Animals © 2011 Pearson Education, Inc.

63. Dispersal by Wind Dandelion “seeds” (actually one-seeded fruits) Winged fruit of a maple Dandelion fruit Tumbleweed Dispersal by Water Winged seed of the tropical Asian climbing gourd Alsomitra macrocarpa Coconut seed embryo, endosperm, and endocarp inside buoyant husk Figure 38.11a

64. Figure 38.11b Dispersal by Animals Fruit of puncture vine (Tribulus terrestris) Squirrel hoarding seeds or fruits underground Ant carrying seed with nutritious “food body” to its nest Seeds dispersed in black bear feces

65. Concept 38.2: Flowering plants reproduce sexually, asexually, or both Many angiosperm species reproduce both asexually and sexually Sexual reproduction results in offspring that are genetically different from their parents Asexual reproduction results in a clone of genetically identical organisms © 2011 Pearson Education, Inc.

66. Mechanisms of Asexual Reproduction Fragmentation, separation of a parent plant into parts that develop into whole plants, is a very common type of asexual reproduction In some species, a parent plant’s root system gives rise to adventitious shoots that become separate shoot systems © 2011 Pearson Education, Inc.

67. Figure 38.12

68. Apomixis is the asexual production of seeds from a diploid cell © 2011 Pearson Education, Inc.

69. Advantages and Disadvantages of Asexual Versus Sexual Reproduction Asexual reproduction is also called vegetative reproduction Asexual reproduction can be beneficial to a successful plant in a stable environment However, a clone of plants is vulnerable to local extinction if there is an environmental change © 2011 Pearson Education, Inc.

70. Sexual reproduction generates genetic variation that makes evolutionary adaptation possible However, only a fraction of seedlings survive Some flowers can self-fertilize to ensure that every ovule will develop into a seed Many species have evolved mechanisms to prevent selfing © 2011 Pearson Education, Inc.

71. Mechanisms That Prevent Self-Fertilization Many angiosperms have mechanisms that make it difficult or impossible for a flower to self-fertilize Dioecious species have staminate and carpellate flowers on separate plants © 2011 Pearson Education, Inc.

72. Figure 38.13 Staminate flowers (left) and carpellate flowers (right) of a dioecious species (a) (b) Thrum and pin flowers Thrum flower Pin flower Stamens Styles

73. The most common is self-incompatibility, a plant’s ability to reject its own pollen Researchers are unraveling the molecular mechanisms involved in self-incompatibility Some plants reject pollen that has an S-gene matching an allele in the stigma cells Recognition of self pollen triggers a signal transduction pathway leading to a block in growth of a pollen tube © 2011 Pearson Education, Inc.

74. Vegetative Propagation and Agriculture Humans have devised methods for asexual propagation of angiosperms Most methods are based on the ability of plants to form adventitious roots or shoots © 2011 Pearson Education, Inc.

75. Clones from Cuttings Many kinds of plants are asexually reproduced from plant fragments called cuttings A callus is a mass of dividing undifferentiated cells that forms where a stem is cut and produces adventitious roots Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2011 Pearson Education, Inc.

76. Grafting A twig or bud can be grafted onto a plant of a closely related species or variety The stock provides the root system The scion is grafted onto the stock © 2011 Pearson Education, Inc.

77. Test-Tube Cloning and Related Techniques Plant biologists have adopted in vitro methods to create and clone novel plant varieties A callus of undifferentiated cells can sprout shoots and roots in response to plant hormones © 2011 Pearson Education, Inc.

78. Figure 38.14 Developing root (a) (b) (c)

79. Transgenic plants are genetically modified (GM) to express a gene from another organism Protoplast fusion is used to create hybrid plants by fusing protoplasts, plant cells with their cell walls removed © 2011 Pearson Education, Inc.

80. Figure 38.15 50  m

81. Figure 38.UN01 Endosperm nucleus (3n) (2 polar nuclei plus sperm) Zygote (2n) (egg plus sperm)

82. Figure 38.UN02