Chapter 38 Presentation

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  • Figure 38.1 Why is this wasp trying to mate with this flower?
  • For the Discovery Video Plant Pollination, go to Animation and Video Files.
  • Figure 38.2 An overview of angiosperm reproduction
  • Figure 38.2 An overview of angiosperm reproduction
  • Figure 38.2 An overview of angiosperm reproduction
  • Figure 38.3 The development of male and female gametophytes in angiosperms
  • Figure 38.3a The development of male and female gametophytes in angiosperms
  • Figure 38.3b The development of male and female gametophytes in angiosperms
  • Figure 38.4 Flower pollination
  • Figure 38.4 Flower pollination
  • Figure 38.4 Flower pollination
  • Figure 38.4 Flower pollination
  • Figure 38.4 Flower pollination
  • Figure 38.4 Flower pollination
  • Figure 38.5 Growth of the pollen tube and double fertilization
  • Figure 38.5 Growth of the pollen tube and double fertilization
  • Figure 38.5 Growth of the pollen tube and double fertilization
  • Figure 38.5 Growth of the pollen tube and double fertilization
  • Figure 38.6 Do GABA gradients play a role in directing pollen tubes to the eggs in Arabidopsis ?
  • Figure 38.7 The development of a eudicot plant embryo
  • Figure 38.8 Seed structure
  • Figure 38.8a Seed structure
  • Figure 38.8b Seed structure
  • Figure 38.8c Seed structure
  • Figure 38.9 Two common types of seed germination
  • Figure 38.9a Two common types of seed germination
  • Figure 38.9b Two common types of seed germination
  • Figure 38.10 Developmental origin of fruits
  • Figure 38.10a Developmental origin of fruits
  • Figure 38.10b Developmental origin of fruits
  • Figure 38.10c Developmental origin of fruits
  • Figure 38.10d Developmental origin of fruits
  • Figure 38.11 Fruit and seed dispersal
  • Figure 38.11 Fruit and seed dispersal
  • Figure 38.11 Fruit and seed dispersal
  • Figure 38.12 Asexual reproduction in aspen trees
  • Figure 38.13 Some floral adaptations that prevent self-fertilization
  • Figure 38.13a Some floral adaptations that prevent self-fertilization
  • Figure 38.13b Some floral adaptations that prevent self-fertilization
  • Figure 38.14 Test-tube cloning of carrots
  • Figure 38.15 Protoplasts
  • Figure 38.16 Maize: a product of artificial selection For the Discovery Video Colored Cotton, go to Animation and Video Files.
  • Figure 38.17 Genetically modified papaya
  • Figure 38.18 “Golden Rice” and prevention of blindness associated with vitamin A deficiency
  • Chapter 38 Presentation

    1. 1. Chapter 38 Angiosperm Reproduction and Biotechnology
    2. 2. Overview: Flowers of Deceit <ul><li>Angiosperm flowers can attract pollinators using visual cues and volatile chemicals </li></ul><ul><li>Many angiosperms reproduce sexually and asexually </li></ul><ul><li>Symbiotic relationships are common between plants and other species </li></ul><ul><li>Since the beginning of agriculture, plant breeders have genetically manipulated traits of wild angiosperm species by artificial selection </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    3. 3. Fig. 38-1
    4. 4. Concept 38.1: Flowers, double fertilization, and fruits are unique features of the angiosperm life cycle <ul><li>Diploid (2 n ) sporophytes produce spores by meiosis; these grow into haploid ( n ) gametophytes </li></ul><ul><li>Gametophytes produce haploid ( n ) gametes by mitosis; fertilization of gametes produces a sporophyte </li></ul>Video: Flower Blooming (time lapse) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    5. 5. <ul><li>In angiosperms, the sporophyte is the dominant generation, the large plant that we see </li></ul><ul><li>The gametophytes are reduced in size and depend on the sporophyte for nutrients </li></ul><ul><li>The angiosperm life cycle is characterized by “three Fs”: f lowers, double f ertilization, and f ruits </li></ul>Video: Flower Plant Life Cycle (time lapse) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    6. 6. Fig. 38-2 Stamen Anther Filament Stigma Carpel Style Ovary Anther Pollen tube Germinated pollen grain ( n ) (male gametophyte) Ovary Ovule Embryo sac ( n ) (female gametophyte) Egg ( n ) Sperm ( n ) Zygote (2 n ) Seed Seed Embryo (2 n ) (sporophyte) Simple fruit Germinating seed Mature sporophyte plant (2 n ) (b) Simplified angiosperm life cycle Key Receptacle Sepal Petal (a) Structure of an idealized flower Haploid ( n ) Diploid (2 n ) FERTILIZATION
    7. 7. Fig. 38-2a Stamen Anther Filament Stigma Carpel Style Ovary Receptacle Sepal Petal (a) Structure of an idealized flower
    8. 8. Fig. 38-2b Anther Pollen tube Germinated pollen grain ( n ) (male gametophyte) Ovary Ovule Embryo sac ( n ) (female gametophyte) Egg ( n ) Sperm ( n ) Zygote (2 n ) Seed Seed Embryo (2 n ) (sporophyte) Simple fruit Germinating seed Mature sporophyte plant (2 n ) (b) Simplified angiosperm life cycle Key Haploid ( n ) Diploid (2 n ) FERTILIZATION
    9. 9. Flower Structure and Function <ul><li>Flowers are the reproductive shoots of the angiosperm sporophyte; they attach to a part of the stem called the receptacle </li></ul><ul><li>Flowers consist of four floral organs: sepals , petals , stamens , and carpels </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    10. 10. <ul><li>A stamen consists of a filament topped by an anther with pollen sacs that produce pollen </li></ul><ul><li>A carpel has a long style with a stigma on which pollen may land </li></ul><ul><li>At the base of the style is an ovary containing one or more ovules </li></ul><ul><li>A single carpel or group of fused carpels is called a pistil </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    11. 11. <ul><li>Complete flowers contain all four floral organs </li></ul><ul><li>Incomplete flowers lack one or more floral organs, for example stamens or carpels </li></ul><ul><li>Clusters of flowers are called inflorescences </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    12. 12. Development of Male Gametophytes in Pollen Grains <ul><li>Pollen develops from microspores within the microsporangia, or pollen sacs, of anthers </li></ul><ul><li>If pollination succeeds, a pollen grain produces a pollen tube that grows down into the ovary and discharges sperm near the embryo sac </li></ul><ul><li>The pollen grain consists of the two-celled male gametophyte and the spore wall </li></ul>Video: Bat Pollinating Agave Plant Video: Bee Pollinating Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    13. 13. Fig. 38-3 (a) Development of a male gametophyte (in pollen grain) Microsporangium (pollen sac) Microsporocyte (2 n ) 4 microspores ( n ) Each of 4 microspores ( n ) Male gametophyte Generative cell ( n ) Ovule (b) Development of a female gametophyte (embryo sac) Megasporangium (2 n ) Megasporocyte (2 n ) Integuments (2 n ) Micropyle MEIOSIS Surviving megaspore ( n ) 3 antipodal cells ( n ) 2 polar nuclei ( n ) 1 egg ( n ) 2 synergids ( n ) Female gametophyte (embryo sac) Ovule Embryo sac Integuments (2 n ) Ragweed pollen grain Nucleus of tube cell ( n ) MITOSIS 100 µm 20 µm 75 µm
    14. 14. Fig. 38-3a (a) Development of a male gametophyte (in pollen grain) Microsporangium (pollen sac) Microsporocyte (2 n ) 4 microspores ( n ) Each of 4 microspores ( n ) Male gametophyte Generative cell ( n ) MEIOSIS Ragweed pollen grain Nucleus of tube cell ( n ) MITOSIS 20 µm 75 µm
    15. 15. Development of Female Gametophytes (Embryo Sacs) <ul><li>Within an ovule, megaspores are produced by meiosis and develop into embryo sacs, the female gametophytes </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    16. 16. Fig. 38-3b Ovule (b) Development of a female gametophyte (embryo sac) Megasporangium (2 n ) Megasporocyte (2 n ) Integuments (2 n ) Micropyle MEIOSIS Surviving megaspore ( n ) 3 antipodal cells ( n ) 2 polar nuclei ( n ) 1 egg ( n ) 2 synergids ( n ) Female gametophyte (embryo sac) Ovule Embryo sac Integuments (2 n ) MITOSIS 100 µm
    17. 17. Pollination <ul><li>In angiosperms, pollination is the transfer of pollen from an anther to a stigma </li></ul><ul><li>Pollination can be by wind, water, bee, moth and butterfly, fly, bird, bat, or water </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    18. 18. Fig. 38-4a Abiotic Pollination by Wind Hazel staminate flowers (stamens only) Hazel carpellate flower (carpels only)
    19. 19. Fig. 38-4b Pollination by Bees Common dandelion under normal light Common dandelion under ultraviolet light
    20. 20. Fig. 38-4c Pollination by Moths and Butterflies Moth on yucca flower Anther Stigma
    21. 21. Fig. 38-4d Pollination by Flies Blowfly on carrion flower Fly egg
    22. 22. Fig. 38-4e Hummingbird drinking nectar of poro flower Pollination by Birds
    23. 23. Fig. 38-4f Long-nosed bat feeding on cactus flower at night Pollination by Bats
    24. 24. Double Fertilization <ul><li>After landing on a receptive stigma, a pollen grain produces a pollen tube that extends between the cells of the style toward the ovary </li></ul><ul><li>Double fertilization results from the discharge of two sperm from the pollen tube into the embryo sac </li></ul><ul><li>One sperm fertilizes the egg, and the other combines with the polar nuclei, giving rise to the triploid (3 n ) food-storing endosperm </li></ul>Animation: Plant Fertilization Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    25. 25. Fig. 38-5 Stigma Pollen tube 2 sperm Style Ovary Ovule Micropyle Ovule Polar nuclei Egg Synergid 2 sperm Endosperm nucleus (3 n ) (2 polar nuclei plus sperm) Zygote (2 n ) (egg plus sperm) Egg Pollen grain Polar nuclei
    26. 26. Fig. 38-5a Stigma Pollen tube 2 sperm Style Ovary Ovule Micropyle Egg Pollen grain Polar nuclei
    27. 27. Fig. 38-5b Ovule Polar nuclei Egg Synergid 2 sperm
    28. 28. Fig. 38-5c Endosperm nucleus (3 n ) (2 polar nuclei plus sperm) Zygote (2 n ) (egg plus sperm)
    29. 29. Fig. 38-6 Wild-type Arabidopsis Micropyle Ovule Pollen tube growing toward micropyle Seed stalk Many pollen tubes outside seed stalk Seed stalk 20 µm Ovule pop2 mutant Arabidopsis EXPERIMENT
    30. 30. Seed Development, Form, and Function <ul><li>After double fertilization, each ovule develops into a seed </li></ul><ul><li>The ovary develops into a fruit enclosing the seed(s) </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    31. 31. Endosperm Development <ul><li>Endosperm development usually precedes embryo development </li></ul><ul><li>In most monocots and some eudicots, endosperm stores nutrients that can be used by the seedling </li></ul><ul><li>In other eudicots, the food reserves of the endosperm are exported to the cotyledons </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    32. 32. Embryo Development <ul><li>The first mitotic division of the zygote is transverse, splitting the fertilized egg into a basal cell and a terminal cell </li></ul>Animation: Seed Development Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    33. 33. Fig. 38-7 Ovule Endosperm nucleus Integuments Zygote Zygote Terminal cell Basal cell Basal cell Proembryo Suspensor Cotyledons Shoot apex Root apex Seed coat Endosperm Suspensor
    34. 34. Structure of the Mature Seed <ul><li>The embryo and its food supply are enclosed by a hard, protective seed coat </li></ul><ul><li>The seed enters a state of dormancy </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    35. 35. <ul><li>In some eudicots, such as the common garden bean, the embryo consists of the embryonic axis attached to two thick cotyledons (seed leaves) </li></ul><ul><li>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 </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    36. 36. Fig. 38-8 Epicotyl Hypocotyl Cotyledons Radicle Seed coat Seed coat Endosperm (a) Common garden bean, a eudicot with thick cotyledons Cotyledons Epicotyl Hypocotyl Radicle (b) Castor bean, a eudicot with thin cotyledons (c) Maize, a monocot Scutellum (cotyledon) Pericarp fused with seed coat Endosperm Epicotyl Hypocotyl Coleoptile Radicle Coleorhiza
    37. 37. Fig. 38-8a Epicotyl Hypocotyl Cotyledons Radicle Seed coat (a) Common garden bean, a eudicot with thick cotyledons
    38. 38. <ul><li>The seeds of some eudicots, such as castor beans, have thin cotyledons </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    39. 39. Fig. 38-8b Seed coat Endosperm Cotyledons Epicotyl Hypocotyl Radicle (b) Castor bean, a eudicot with thin cotyledons
    40. 40. <ul><li>A monocot embryo has one cotyledon </li></ul><ul><li>Grasses, such as maize and wheat, have a special cotyledon called a scutellum </li></ul><ul><li>Two sheathes enclose the embryo of a grass seed: a coleoptile covering the young shoot and a coleorhiza covering the young root </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    41. 41. Fig. 38-8c (c) Maize, a monocot Scutellum (cotyledon) Pericarp fused with seed coat Endosperm Epicotyl Hypocotyl Coleoptile Radicle Coleorhiza
    42. 42. Seed Dormancy: An Adaptation for Tough Times <ul><li>Seed dormancy increases the chances that germination will occur at a time and place most advantageous to the seedling </li></ul><ul><li>The breaking of seed dormancy often requires environmental cues, such as temperature or lighting changes </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    43. 43. Seed Germination and Seedling Development <ul><li>Germination depends on imbibition , the uptake of water due to low water potential of the dry seed </li></ul><ul><li>The radicle (embryonic root) emerges first </li></ul><ul><li>Next, the shoot tip breaks through the soil surface </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    44. 44. <ul><li>In many eudicots, a hook forms in the hypocotyl, and growth pushes the hook above ground </li></ul><ul><li>The hook straightens and pulls the cotyledons and shoot tip up </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    45. 45. Fig. 38-9 (a) Common garden bean Seed coat Radicle Hypocotyl Hypocotyl Cotyledon Cotyledon Cotyledon Hypocotyl Epicotyl Foliage leaves (b) Maize Radicle Foliage leaves Coleoptile Coleoptile
    46. 46. Fig. 38-9a (a) Common garden bean Seed coat Radicle Hypocotyl Cotyledon Cotyledon Hypocotyl Epicotyl Foliage leaves Cotyledon Hypocotyl
    47. 47. <ul><li>In maize and other grasses, which are monocots, the coleoptile pushes up through the soil </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    48. 48. Fig. 38-9b (b) Maize Radicle Foliage leaves Coleoptile Coleoptile
    49. 49. Fruit Form and Function <ul><li>A fruit develops from the ovary </li></ul><ul><li>It protects the enclosed seeds and aids in seed dispersal by wind or animals </li></ul><ul><li>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 </li></ul>Animation: Fruit Development Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    50. 50. <ul><li>Fruits are also classified by their development: </li></ul><ul><ul><li>Simple , a single or several fused carpels </li></ul></ul><ul><ul><li>Aggregate, a single flower with multiple separate carpels </li></ul></ul><ul><ul><li>Multiple, a group of flowers called an inflorescence </li></ul></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    51. 51. Fig. 38-10 Flower Stamen Carpels Ovary Stigma Pea flower Ovule Seed Carpel (fruitlet) Raspberry flower Stigma Ovary Stamen Stamen Pineapple inflorescence Apple flower Stigma Stamen Ovule Each segment develops from the carpel of one flower Pea fruit Raspberry fruit Pineapple fruit Apple fruit (a) Simple fruit (b) Aggregate fruit (c) Multiple fruit (d) Accessory fruit Sepal Petal Style Ovary (in receptacle) Sepals Seed Receptacle Remains of stamens and styles
    52. 52. Fig. 38-10a Ovary Stigma Pea flower Ovule Seed Stamen Pea fruit (a) Simple fruit
    53. 53. Fig. 38-10b Stamen Carpels Carpel (fruitlet) Raspberry flower Stigma Ovary Stamen Raspberry fruit (b) Aggregate fruit
    54. 54. Fig. 38-10c Flower Pineapple inflorescence Each segment develops from the carpel of one flower Pineapple fruit (c) Multiple fruit
    55. 55. <ul><li>An accessory fruit contains other floral parts in addition to ovaries </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    56. 56. Fig. 38-10d Apple flower Stigma Stamen Ovule Apple fruit (d) Accessory fruit Sepal Petal Style Ovary (in receptacle) Sepals Seed Receptacle Remains of stamens and styles
    57. 57. <ul><li>Fruit dispersal mechanisms include: </li></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Wind </li></ul></ul><ul><ul><li>Animals </li></ul></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    58. 58. Fig. 38-11a Coconut Dispersal by Water
    59. 59. Fig. 38-11b Tumbleweed Dispersal by Wind Winged fruit of maple Dandelion “parachute” Winged seed of Asian climbing gourd
    60. 60. Fig. 38-11c Dispersal by Animals Seeds carried to ant nest Seeds buried in caches Seeds in feces Barbed fruit
    61. 61. Concept 38.2: Plants reproduce sexually, asexually, or both <ul><li>Many angiosperm species reproduce both asexually and sexually </li></ul><ul><li>Sexual reproduction results in offspring that are genetically different from their parents </li></ul><ul><li>Asexual reproduction results in a clone of genetically identical organisms </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    62. 62. Mechanisms of Asexual Reproduction <ul><li>Fragmentation , separation of a parent plant into parts that develop into whole plants, is a very common type of asexual reproduction </li></ul><ul><li>In some species, a parent plant’s root system gives rise to adventitious shoots that become separate shoot systems </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    63. 63. Fig. 38-12
    64. 64. <ul><li>Apomixis is the asexual production of seeds from a diploid cell </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    65. 65. Advantages and Disadvantages of Asexual Versus Sexual Reproduction <ul><li>Asexual reproduction is also called vegetative reproduction </li></ul><ul><li>Asexual reproduction can be beneficial to a successful plant in a stable environment </li></ul><ul><li>However, a clone of plants is vulnerable to local extinction if there is an environmental change </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    66. 66. <ul><li>Sexual reproduction generates genetic variation that makes evolutionary adaptation possible </li></ul><ul><li>However, only a fraction of seedlings survive </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    67. 67. Mechanisms That Prevent Self-Fertilization <ul><li>Many angiosperms have mechanisms that make it difficult or impossible for a flower to self-fertilize </li></ul><ul><li>Dioecious species have staminate and carpellate flowers on separate plants </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    68. 68. Fig. 38-13 (a) Sagittaria latifolia staminate flower (left) and carpellate flower (right) (b) Oxalis alpina flowers Thrum flower Pin flower Stamens Styles Styles Stamens
    69. 69. Fig. 38-13a Sagittaria latifolia staminate flower (left) and carpellate flower (right) (a)
    70. 70. <ul><li>Others have stamens and carpels that mature at different times or are arranged to prevent selfing </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    71. 71. Fig. 38-13b (b) Oxalis alpina flowers Thrum flower Pin flower Stamens Styles Styles Stamens
    72. 72. <ul><li>The most common is self-incompatibility , a plant’s ability to reject its own pollen </li></ul><ul><li>Researchers are unraveling the molecular mechanisms involved in self-incompatibility </li></ul><ul><li>Some plants reject pollen that has an S -gene matching an allele in the stigma cells </li></ul><ul><li>Recognition of self pollen triggers a signal transduction pathway leading to a block in growth of a pollen tube </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    73. 73. Vegetative Propagation and Agriculture <ul><li>Humans have devised methods for asexual propagation of angiosperms </li></ul><ul><li>Most methods are based on the ability of plants to form adventitious roots or shoots </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    74. 74. Clones from Cuttings <ul><li>Many kinds of plants are asexually reproduced from plant fragments called cuttings </li></ul><ul><li>A callus is a mass of dividing undifferentiated cells that forms where a stem is cut and produces adventitious roots </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    75. 75. Grafting <ul><li>A twig or bud can be grafted onto a plant of a closely related species or variety </li></ul><ul><li>The stock provides the root system </li></ul><ul><li>The scion is grafted onto the stock </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    76. 76. Test-Tube Cloning and Related Techniques <ul><li>Plant biologists have adopted in vitro methods to create and clone novel plant varieties </li></ul><ul><li>Transgenic plants are genetically modified (GM) to express a gene from another organism </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    77. 77. Fig. 38-14 (b) Differentiation into plant (a) Undifferentiated carrot cells
    78. 78. <ul><li>Protoplast fusion is used to create hybrid plants by fusing protoplasts, plant cells with their cell walls removed </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    79. 79. Fig. 38-15 50 µm
    80. 80. Concept 38.3: Humans modify crops by breeding and genetic engineering <ul><li>Humans have intervened in the reproduction and genetic makeup of plants for thousands of years </li></ul><ul><li>Hybridization is common in nature and has been used by breeders to introduce new genes </li></ul><ul><li>Maize, a product of artificial selection, is a staple in many developing countries </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    81. 81. Fig. 38-16
    82. 82. Plant Breeding <ul><li>Mutations can arise spontaneously or can be induced by breeders </li></ul><ul><li>Plants with beneficial mutations are used in breeding experiments </li></ul><ul><li>Desirable traits can be introduced from different species or genera </li></ul><ul><li>The grain triticale is derived from a successful cross between wheat and rye </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    83. 83. Plant Biotechnology and Genetic Engineering <ul><li>Plant biotechnology has two meanings: </li></ul><ul><ul><li>In a general sense, it refers to innovations in the use of plants to make useful products </li></ul></ul><ul><ul><li>In a specific sense, it refers to use of GM organisms in agriculture and industry </li></ul></ul><ul><li>Modern plant biotechnology is not limited to transfer of genes between closely related species or varieties of the same species </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    84. 84. Reducing World Hunger and Malnutrition <ul><li>Genetically modified plants may increase the quality and quantity of food worldwide </li></ul><ul><li>Transgenic crops have been developed that: </li></ul><ul><ul><li>Produce proteins to defend them against insect pests </li></ul></ul><ul><ul><li>Tolerate herbicides </li></ul></ul><ul><ul><li>Resist specific diseases </li></ul></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    85. 85. Fig. 38-17
    86. 86. <ul><li>Nutritional quality of plants is being improved </li></ul><ul><li>“ Golden Rice” is a transgenic variety being developed to address vitamin A deficiencies among the world’s poor </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    87. 87. Fig. 38-18 Genetically modified rice Ordinary rice
    88. 88. <ul><li>Biofuels are made by the fermentation and distillation of plant materials such as cellulose </li></ul><ul><li>Biofuels can be produced by rapidly growing crops </li></ul>Reducing Fossil Fuel Dependency Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    89. 89. The Debate over Plant Biotechnology <ul><li>Some biologists are concerned about risks of releasing GM organisms into the environment </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    90. 90. Issues of Human Health <ul><li>One concern is that genetic engineering may transfer allergens from a gene source to a plant used for food </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    91. 91. Possible Effects on Nontarget Organisms <ul><li>Many ecologists are concerned that the growing of GM crops might have unforeseen effects on nontarget organisms </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    92. 92. Addressing the Problem of Transgene Escape <ul><li>Perhaps the most serious concern is the possibility of introduced genes escaping into related weeds through crop-to-weed hybridization </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    93. 93. <ul><li>Efforts are underway to prevent this by introducing: </li></ul><ul><ul><li>Male sterility </li></ul></ul><ul><ul><li>Apomixis </li></ul></ul><ul><ul><li>Transgenes into chloroplast DNA (not transferred by pollen) </li></ul></ul><ul><ul><li>Strict self-pollination </li></ul></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    94. 94. Fig. 38-UN1 Endosperm nucleus (3 n ) (2 polar nuclei plus sperm) Zygote (2 n ) (egg plus sperm)
    95. 95. Fig. 38-UN2
    96. 96. You should now be able to: <ul><li>Describe how the plant life cycle is modified in angiosperms </li></ul><ul><li>Identify and describe the function of a sepal, petal, stamen (filament and anther), carpel (style, ovary, ovule, and stigma), seed coat, hypocotyl, radicle, epicotyl, endosperm, cotyledon </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    97. 97. You should now be able to: <ul><li>Distinguish between complete and incomplete flowers; bisexual and unisexual flowers; microspores and megaspores; simple, aggregate, multiple, and accessory fruit </li></ul><ul><li>Describe the process of double fertilization </li></ul><ul><li>Describe the fate and function of the ovule, ovary, and endosperm after fertilization </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
    98. 98. <ul><li>Explain the advantages and disadvantages of reproducing sexually and asexually </li></ul><ul><li>Name and describe several natural and artificial mechanisms of asexual reproduction </li></ul><ul><li>Discuss the risks of transgenic crops and describe four strategies that may prevent transgene escape </li></ul>Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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