Biology Sylvia S. Mader Michael Windelspecht Chapter 27 Flowering Plants: Reproduction Lecture Outline See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1

Reproduction in Plants Biology, 9th ed, Sylvia Mader Chapter 28 Slide #2 Outline Reproduction in Plants 27.1 Sexual Reproductive Strategies 27.2 Seed Development 27.3 Fruit Types and Dispersal 27.4 Asexual Reproductive Strategies 2

27.1 Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 27.1 Sexual Reproductive Strategies Reproduction in Plants Plants have a two-stage, alternating life cycle Sporophyte produces haploid spores by meiosis Spores divide mitotically to become haploid gametophytes Gametophytes produce gametes Gametes fuse to produce a diploid zygote Zygote divides mitotically to become the diploid sporophyte

Sexual Reproduction in Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 28 Slide #4 Sexual Reproduction in Flowering Plants Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anther 2 ovule ovary microspore megaspore 4

Sexual Reproduction in Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 28 Slide #5 Sexual Reproduction in Flowering Plants Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anther 7 seed 2 ovule ovary zygote 6 FERTILIZATION MEIOSIS 3 microspore egg megaspore sperm 4 5 mitosis Male gametophyte (pollen graIn) Female gametophyte (embryo sac) 5

Sexual Reproduction in Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 28 Slide #6 Sexual Reproduction in Flowering Plants Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 mitosis anther 1 7 sporophyte seed 2 ovule zygote diploid(2n) ovary 6 FERTILIZATION MEIOSIS haploid(n) 3 microspore egg megaspore sperm 4 5 mitosis Male gametophyte (pollen graIn) Female gametophyte (embryo sac) 6

Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 Sexual Reproductive Strategies Reproduction in Plants A flower produces two types of spores Microspore - Male gametophyte Undergoes mitosis Becomes pollen grain Megaspore - Female gametophyte Becomes the female gametophyte, an embryo sac within an ovule within an ovary Ovule becomes a seed Ovary becomes a fruit

Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 Sexual Reproductive Strategies Reproduction in Plants Flowers Flowering occurs in response to environmental signals such as day length In monocots, flower parts occur in threes and multiples of three In eudicots, flower parts occur in fours or fives and multiples of four or five

Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 Sexual Reproductive Strategies Reproduction in Plants A typical flower has four whorls of modified leaves attached to a receptacle at the end of a flower stalk called a peduncle Sepals protect the bud Petals attract pollinators Stamens are male portion of flower Anther - Saclike container Filament - Slender stalk Carpel is the female portion of flower Stigma - Enlarged sticky knob Style - Slender stalk Ovary - Enlarged base enclosing ovules

Biology, 9th ed, Sylvia Mader Chapter 28 Anatomy of a Flower Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. stamen carpel anther stigma filament style ovary petal ovule receptacle sepal peduncle

Monocot vs. Eudicot Flowers Biology, 9th ed, Sylvia Mader Monocot vs. Eudicot Flowers Chapter 28 Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. p3 p2 carpel stamen p4 petal p1 p5 b. Festive azalea, Rhododendron sp. b: © Pat Pendarvis

Life Cycle of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 28 Life Cycle of Flowering Plants Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anther ovule ovary Sporophyte

Life Cycle of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 28 Slide #13 Life Cycle of Flowering Plants Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anther Development of the male gametophyte: Development of the female gametophyte: In pollen sacs of the anther, a microspore mother cell undergoes meiosis to produce 4 microspores each. In an ovule within an ovary, a megaspore mother cell undergoes meiosis to produce 4 megaspores. anther ovule ovary Ovule Pollen sac ovary microspore mother cell megaspore mother cell Sporophyte MEIOSIS MEIOSIS ovule wall Microspores Megaspores megaspore 3 megaspores disintegrate integument micropyle 13

Life Cycle of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 28 Slide #14 Life Cycle of Flowering Plants Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anther Development of the male gametophyte: Development of the female gametophyte: In pollen sacs of the anther, a microspore mother cell undergoes meiosis to produce 4 microspores each In an ovule within an ovary, a megaspore mother cell undergoes meiosis to produce 4 megaspores anther ovule Pollen sac ovary Ovule ovary microspore megaspore Sporophyte mother cell mother cell MEIOSIS MEIOSIS ovule wall tube cell Microspores generative cell Megaspores mitosis Microspores develop into male gametophytes (pollen grains). megaspore Pollen grain (male gametophyte) ovule 3 megaspores disintegrate wall One megaspore becomes the embryo sac (female gametophyte). integument antipodals mitosis micropyle polar nuclei egg cell synergids Embryo sac (mature female gametophyte) 14 (Top): Courtesy Graham Kent; (Bottom): © Ed Reschke

Life Cycle of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 28 Slide #15 Life Cycle of Flowering Plants Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. anther Development of the male gametophyte: Development of the female gametophyte: In pollen sacs of the anther , a microspore mother cell undergoes meiosis to produce 4 microspores each In an ovule within an ovary, a megaspore mother cell undergoes meiosis to Produce 4 megaspores. Mature Seed seed coat anther The ovule develops into a seed containing the embryonic sporophyte and endosperm. mitosis ovule Pollen sac ovary Ovule ovary embryo endosperm (3n) microspore mother cell megaspore mother cell Sporophyte Seed diploid (2n) DOUBLE FERTILIZATION MEIOSIS MEIOSIS haploid (n) ovule wall Pollination tube cell Microspores During double fertilization, one sperm from the Male gametophyte Will fertilize the egg; another Sperm will join with polar nuclei to produce the 3n endosperm. Development of the sporophyte: generative cell Megaspores Pollination occurs; a pollen grain germinates and produces a pollen Microspores develop into male gametophytes (pollen grains). mitosis megaspore pollen tube ovule Pollen grain (male gametophyte) wall 3 megaspores disintegrate sperm antipodals One megaspore becomes the embryo sac (female gametophyte). mitosis integument Mature male gametophyte polar nuclei micropyle polar nuclei tube cell nucleus egg cell synergids egg sperm Embryo sac (mature female gametophyte) (Top): Courtesy Graham Kent; (Bottom): © Ed Reschke 15

Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 Sexual Reproductive Strategies Reproduction in Plants Male Gametophytes Microspores are produced in anthers Each anther has four pollen sacs, each with many microspore mother cells Microspore mother cells undergo meiosis to produce microspores Microspores undergo mitosis to produce pollen grains

Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 Sexual Reproductive Strategies Reproduction in Plants The ovary contains one or more ovules An ovule has a central mass of parenchyma cells covered by integuments One parenchyma cell enlarges to become a megaspore mother cell The megaspore mother cell undergoes meiosis to produce four haploid megaspores, three of which are nonfunctional The functional megaspore divides mitotically until there are eight nuclei in the female gametophyte The female gametophyte (embryo sac) contains One egg cell associated with two synergid cells One central cell with two polar nuclei Three antipodal cells

Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 Sexual Reproductive Strategies Reproduction in Plants Pollination The transfer of pollen from an anther to the stigma of a carpel Self-pollination occurs if the pollen is from the same plant Cross-pollination occurs if the pollen is from a different plant

Sexual Reproductive Strategies Biology, 9th ed, Sylvia Mader Chapter 28 Sexual Reproductive Strategies Reproduction in Plants Fertilization When a pollen grain lands on the stigma, it germinates, forming a pollen tube The pollen tube passes between the stigma and style to reach the micropyle of the ovule Double fertilization occurs One sperm nucleus unites with the egg nucleus, producing a 2n zygote The other sperm nucleus unites with the polar nuclei, forming a 3n endosperm nucleus, which develops into the endosperm A mature seed contains the embryo, stored food, and the seed coat

Plants and Their Pollinators Biology, 9th ed, Sylvia Mader Chapter 28 Plants and Their Pollinators Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b. Ba: © Anthony Mercieca/Photo Researchers, Inc.; Bb: © Merlin D. Tuttle/Bat Conservation International;

Biology, 9th ed, Sylvia Mader Chapter 28 27.2 Seed Development Reproduction in Plants Development: Programmed series of stages from a simple to a more complex form Development of a eudicot embryo After double fertilization, the zygote divides repeatedly to form a proembryo and a suspensor During the globular stage, the proembryo is a ball of cells The outermost cells will become dermal tissue

Biology, 9th ed, Sylvia Mader Chapter 28 Seed Development Reproduction in Plants Heart and Torpedo Stages The embryo is heart shaped when cotyledons appear The embryo enlarges, elongates, and takes on a torpedo shape

Biology, 9th ed, Sylvia Mader Chapter 28 Seed Development Reproduction in Plants Mature Embryo The epicotyl is the portion between cotyledons contributing to shoot development The hypocotyl is the portion below that contributes to stem development The radicle is the embryonic root

Development of an Eudicot Embryo Biology, 9th ed, Sylvia Mader Chapter 28 Development of an Eudicot Embryo Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arabidopsis thaliana endosperm endosperm nucleus embryo suspensor zygote basal cell 1 Zygote stage: Double fertilization results in zygote (true green) and endosperm. 2 Proembryo stage: Embryo (green) is multicellular and the suspensor (purple) is functional. zygote (Proembryo): Courtesy Dr. Chun-Ming Liu; (Torpedo): © Biology Media/Photo Researchers, Inc.; (Mature embryo): © Jack Bostrack/Visuals Unlimited

Development of an Eudicot Embryo (continued) Biology, 9th ed, Sylvia Mader Chapter 28 Slide #25 Development of an Eudicot Embryo (continued) Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. A. thaliana A. thaliana Capsella Capsella hypocotyl (root axis) epicotyl (shoot apical meristem) shoot apical meristem bending cotyledons endosperm cotyledons appearing seed coat endosperm root apical meristem radicle (root apical meristem) cotyledons 3 Globular stage: Embryo is globe shaped. 4 Heart stage: Embryo is heart shaped. 5 Torpedo stage: Embryo is torpedo shaped; the cotyledons are obvious. 6 Mature embryo stage: The epicotyl will be the shoot system; the hypocotyl will be the root system. (Proembryo): Courtesy Dr. Chun-Ming Liu; (Torpedo): © Biology Media/Photo Researchers, Inc.; (Mature embryo): © Jack Bostrack/Visuals Unlimited 25

Biology, 9th ed, Sylvia Mader Chapter 28 Monocot vs. Eudicot Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. seed coat plumule pericarp hypocotyl endosperm coleoptile radicle cotyledon embryo embryo cotyledon plumule radicle coleorhiza a. b. a: © Dwight Kuhn; b: Courtesy Ray F. Evert/University of Wisconsin Madison

27.3 Fruit Types and Seed Dispersal Biology, 9th ed, Sylvia Mader Chapter 28 27.3 Fruit Types and Seed Dispersal Reproduction in Plants A fruit is a mature ovary Simple Fruits Simple fruits are derived from single ovary with one or several chambers Compound fruits develop from several groups of ovaries Aggregate Fruits Ovaries are from a single flower one receptacle Blackberry Multiple Fruits Ovaries are from separate flowers clustered together Pineapple

Fruit Types and Seed Dispersal Biology, 9th ed, Sylvia Mader Chapter 28 Slide #28 Fruit Types and Seed Dispersal Reproduction in Plants Fruit Development The ovary wall thickens to become the pericarp, which can have three layers The exocarp forms the outermost skin The mesocarp is the fleshy tissue between the exocarp and the endocarp The endocarp is the boundary around the seeds 28

Fruit Types and Seed Dispersal Biology, 9th ed, Sylvia Mader Chapter 28 Fruit Types and Seed Dispersal Reproduction in Plants Fruit Types In dry fruits, the pericarp is paper, leathery, or woody when the fruit is mature Dehiscent - the fruit splits open when ripe Legumes Indehiscent - the fruit does not split open when ripe Grains

Fruit Types and Seed Dispersal Biology, 9th ed, Sylvia Mader Chapter 28 Fruit Types and Seed Dispersal Reproduction in Plants Dispersal of Fruits Many dry fruits are dispersed by wind Woolly hairs, plumes, wings Many fruits attract animals and provide them with food Peaches, cherries, tomatoes

Fruit Dispersal by Animals Biology, 9th ed, Sylvia Mader Chapter 28 Fruit Dispersal by Animals Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b. a: © Marie Read/Animals Animals/Earth Scenes; b: © Scott Camazine/Photo Researchers, Inc.

Fruit Types and Seed Dispersal Biology, 9th ed, Sylvia Mader Chapter 28 Fruit Types and Seed Dispersal Reproduction in Plants Seed Germination When seed germination occurs, the embryo resumes growth and metabolic activity Length of time seeds retain their viability is quite variable Some seeds do not germinate until they have been through a dormant period Temperate zones - Cold Weather

Fruit Types and Seed Dispersal Biology, 9th ed, Sylvia Mader Chapter 28 Fruit Types and Seed Dispersal Reproduction in Plants Environmental requirements for seed germination Availability of oxygen for metabolic needs Adequate temperature for enzyme activity Adequate moisture for hydration of cells

Eudicot and Monocot Seed Structure and Germination Biology, 9th ed, Sylvia Mader Chapter 28 Eudicot and Monocot Seed Structure and Germination Reproduction in Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. cotyledons (two) pericarp plumule endosperm hypocotyl cotyledon (one) radicle coleoptile plumule seed coat radicle cotyledon coleorhiza Seed structure Corn kernel true leaf first true leaves (primary leaves) epicotyl withered cotyledons first leaf seed coat cotyledons (two) hypocotyl coleoptile prop root coleoptile radicle hypocotyl secondary root adventitious root primary root primary root primary root coleorhiza Bean germination and growth Corn germination and growth a. a: © Ed Reschke; b: © James Mauseth b.