Reproduction in Plants Chapter 28. Reproduction in Plants 2Outline Reproductive Strategies ...
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Transcript of Reproduction in Plants Chapter 28. Reproduction in Plants 2Outline Reproductive Strategies ...
Reproduction in Plants
Chapter 28
2Reproduction iReproduction in Plantsn Plants
OutlineOutline
Reproductive StrategiesReproductive StrategiesAlternation of generationsAlternation of generationsAdaptation to a land environmentAdaptation to a land environmentFlowersFlowersPollinationPollination FertilizationFertilization
Seed DevelopmentSeed DevelopmentFruitFruitSeed GerminationSeed GerminationAsexual ReproductionAsexual ReproductionTissue CultureTissue Culture
3Reproduction iReproduction in Plantsn Plants
Reproductive StrategiesReproductive StrategiesAll plants have a two-stage, alternating All plants have a two-stage, alternating life cyclelife cycle
Sporophyte produces haploid spores by Sporophyte produces haploid spores by meiosismeiosis
Spores divide mitotically to become Spores divide mitotically to become haploid gametophyteshaploid gametophytes
Gametophytes produce gametesGametophytes produce gametes
Gametes fuse to produce zygoteGametes fuse to produce zygote
Zygote divides mitotically to become Zygote divides mitotically to become diploid sporophytediploid sporophyte
4Alternation of Generations
in Flowering Plants
5Reproduction iReproduction in Plantsn Plants
Reproductive StrategiesReproductive Strategies
Flower produces two types of sporesFlower produces two types of spores
Microspore - Male gametophyteMicrospore - Male gametophyte
Undergoes mitosisUndergoes mitosis
Becomes pollen grainBecomes pollen grain
Megaspore - Female gametophyteMegaspore - Female gametophyte
Undergoes mitosisUndergoes mitosis
Becomes embryo sac within an ovary, Becomes embryo sac within an ovary, within an ovulewithin an ovule
Ovule becomes seedOvule becomes seed
6Reproduction iReproduction in Plantsn Plants
FlowersFlowers
Flower develops in response to Flower develops in response to environmental signals such as day environmental signals such as day lengthlength
In monocots, flower parts occur in In monocots, flower parts occur in threes and multiples of threethrees and multiples of three
In eudicots, flower parts occur in fours In eudicots, flower parts occur in fours or fives and multiples of four or fiveor fives and multiples of four or five
7Anatomy of a Flower
8Monocot vs. Eudicot Flowers
9Reproduction iReproduction in Plantsn Plants
FlowersFlowers
Leaf-like sepals protect the budLeaf-like sepals protect the bud
Open flower has whorl of petalsOpen flower has whorl of petals
Four whorls of modified leaves Four whorls of modified leaves attached to a receptacle at the end of attached to a receptacle at the end of a flower stalka flower stalk
Receptacle with a single flower is a Receptacle with a single flower is a pedunclepeduncle
Receptacle with several flowers is a Receptacle with several flowers is a pediclepedicle
10Reproduction iReproduction in Plantsn Plants
FlowersFlowers
Leaf-like sepals protect the budLeaf-like sepals protect the bud
Open flower has whorl of petalsOpen flower has whorl of petals
Four whorls of modified leaves Four whorls of modified leaves attached to a receptacle at the end of attached to a receptacle at the end of a flower stalka flower stalk
Receptacle with a single flower is a Receptacle with a single flower is a pedunclepeduncle
Receptacle with several flowers is a Receptacle with several flowers is a pediclepedicle
11Reproduction iReproduction in Plantsn Plants
FlowersFlowers
Stamens are male portion of flowerStamens are male portion of flower
Anther - Saclike containerAnther - Saclike container
Filament - Slender stalkFilament - Slender stalk
Carpel is female portion of flowerCarpel is female portion of flowerStigma - Enlarged sticky knobStigma - Enlarged sticky knobStyle - Slender stalkStyle - Slender stalkOvary - Enlarged base enclosing Ovary - Enlarged base enclosing ovulesovules
12Reproduction iReproduction in Plantsn Plants
FlowersFlowersComplete vs. incomplete flowers:Complete vs. incomplete flowers:
Complete flowers have sepals, petals, Complete flowers have sepals, petals, stamens, and a carpelstamens, and a carpel
Incomplete flowers missing one or more of Incomplete flowers missing one or more of aboveabove
Bisexual vs. unisexual flowers:Bisexual vs. unisexual flowers:Bisexual flowers have both stamens and Bisexual flowers have both stamens and carpelcarpel
Unisexual flowers have one but not the Unisexual flowers have one but not the otherother
Monoecious vs. dioecious plantsMonoecious vs. dioecious plantsMonoecious plants have staminate flowers Monoecious plants have staminate flowers and carpellate flowers on the same plantand carpellate flowers on the same plant
Dioecious plants have all staminate or all Dioecious plants have all staminate or all carpellate flowerscarpellate flowers
13Corn Plants are Monoecious
14Life Cycle of Flowering Plants
15Reproduction iReproduction in Plantsn Plants
From Spores to FertilizationFrom Spores to Fertilization
Male GametophytesMale Gametophytes
Microspores are produced in anthersMicrospores are produced in anthers
Each anther has four pollen sacs, Each anther has four pollen sacs, each with many microsporocyteseach with many microsporocytes
Undergoes meiosis to produce Undergoes meiosis to produce microsporesmicrospores
Mitosis produces pollen grainsMitosis produces pollen grains
16Reproduction iReproduction in Plantsn Plants
PollinationPollination
Pollination is the transfer of pollen Pollination is the transfer of pollen from an anther to the stigma of a from an anther to the stigma of a carpelcarpel
Self-pollination occurs if the pollen is Self-pollination occurs if the pollen is from the same plantfrom the same plant
Cross-pollination occurs if the pollen is Cross-pollination occurs if the pollen is from a different plantfrom a different plant
17Pollination
18Reproduction iReproduction in Plantsn PlantsProduction of Female Production of Female
GametophyteGametophyte
Ovary contains one or more ovulesOvary contains one or more ovules
Ovule has mass of parenchyma cellsOvule has mass of parenchyma cells
One cell enlarges to become One cell enlarges to become megasporocytemegasporocyte
Undergoes meiois and becomes four Undergoes meiois and becomes four haploid megasporeshaploid megaspores
Functional megaspore divides Functional megaspore divides mitotically until there are eight nuclei of mitotically until there are eight nuclei of a female gametophytea female gametophyte
19Reproduction iReproduction in Plantsn Plants
FertilizationFertilization
When pollen grain lands on stigma, it When pollen grain lands on stigma, it germinates forming a pollen tubegerminates forming a pollen tube
Passes between the stigma and style Passes between the stigma and style to reach the micropyle of the ovuleto reach the micropyle of the ovule
Double fertilization occursDouble fertilization occurs
One sperm nucleus unites with the egg One sperm nucleus unites with the egg nucleus, producing a zygotenucleus, producing a zygote
Other sperm nucleus unites with the Other sperm nucleus unites with the polar nuclei, forming a 3n endosperm polar nuclei, forming a 3n endosperm cellcell
20Reproduction iReproduction in Plantsn Plants
Seed DevelopmentSeed Development
Development of eudicot embryoDevelopment of eudicot embryo
After double fertilization, endosperm After double fertilization, endosperm nucleus begins to divide nucleus begins to divide asymmetricallyasymmetrically
Small cell is destined to become the Small cell is destined to become the embryoembryo
Larger cell divides repeatedly to Larger cell divides repeatedly to become a suspensorbecome a suspensor
21Development of a Eudicot Embryo
22Monocot vs. Eudicot
23Reproduction iReproduction in Plantsn Plants
Development of Eudicot EmbryoDevelopment of Eudicot EmbryoDuring globular stage, prembryo is ball of During globular stage, prembryo is ball of cellscells
Outermost cells will become dermal tissueOutermost cells will become dermal tissue
Embryo is heart shaped when cotyledons Embryo is heart shaped when cotyledons appearappear
Epicotyl is portion between cotyledons Epicotyl is portion between cotyledons contributing to shoot developmentcontributing to shoot development
Hypocotyl is portion below that contributes Hypocotyl is portion below that contributes to stem developmentto stem development
Radicle contributes to root developmentRadicle contributes to root development
24Reproduction iReproduction in Plantsn Plants
Fruit Types and Seed DispersalFruit Types and Seed Dispersal
Simple FruitsSimple Fruits
Simple fruits are derived from single Simple fruits are derived from single or several united carpelsor several united carpels
Legumes are fruits that split along two Legumes are fruits that split along two sides when maturesides when mature
Dehiscent - Split openDehiscent - Split open
Indehiscent - Fail to split openIndehiscent - Fail to split open
25Pea Flower and Pea Pod
26Reproduction iReproduction in Plantsn Plants
Simple FruitsSimple Fruits
FleshyFleshy
DrupeDrupe
BerryBerry
PomePome
DryDry
FollicleFollicle
LegumeLegume
CapsuleCapsule
AcheneAchene
NutNut
GrainGrain
27Reproduction iReproduction in Plantsn Plants
Simple FruitsSimple FruitsDispersalDispersal
Many seeds are dispersed by windMany seeds are dispersed by wind
Woolly hairs, plumes, wingsWoolly hairs, plumes, wings
Fleshy fruits - Attract animals and Fleshy fruits - Attract animals and provide them with foodprovide them with food
Peaches, cherries, tomatoesPeaches, cherries, tomatoes
Accessory fruit - Bulk of fruit is not Accessory fruit - Bulk of fruit is not from ovary, but from receptaclefrom ovary, but from receptacle
ApplesApples
28Structure and Function of Fruits
29Reproduction iReproduction in Plantsn Plants
Compound FruitsCompound Fruits
Compound fruits develop from several Compound fruits develop from several individual ovariesindividual ovaries
Aggregate FruitsAggregate Fruits
Ovaries are from a single flowerOvaries are from a single flower
BlackberryBlackberry
Multiple Fruits Multiple Fruits
Ovaries are from separate flowers Ovaries are from separate flowers clustered togetherclustered together
30Reproduction iReproduction in Plantsn Plants
Seed GerminationSeed Germination
When seed germination occurs, the When seed germination occurs, the embryo resumes growth and embryo resumes growth and metabolic activitymetabolic activity
Length of time seeds retain their Length of time seeds retain their viability is quite variableviability is quite variable
Some seeds do not germinate until Some seeds do not germinate until they have been through a dormant they have been through a dormant periodperiod
Temperate zones - Cold WeatherTemperate zones - Cold Weather
Deserts - RainDeserts - Rain
31Reproduction iReproduction in Plantsn Plants
Seed GerminationSeed Germination
Environmental requirements for seed Environmental requirements for seed germinationgermination
Availability of oxygen for metabolic needsAvailability of oxygen for metabolic needs
Adequate temperature for enzyme activityAdequate temperature for enzyme activity
Adequate moisture for hydration of cellsAdequate moisture for hydration of cells
Light (in some cases)Light (in some cases)
Respiration and metabolism continue Respiration and metabolism continue throughout dormancy, but at a reduced throughout dormancy, but at a reduced levellevel
32Seed Structure and Germination
in the Common Garden Bean
33Corn Kernel Structure and Germination
34Reproduction iReproduction in Plantsn Plants
Asexual Reproduction in PlantsAsexual Reproduction in Plants
Plants contain nondifferentiated Plants contain nondifferentiated meristem tissuemeristem tissue
Allows them to reproduce asexually by Allows them to reproduce asexually by vegetative propagationvegetative propagation
Plant hormone auxin:Plant hormone auxin:
Can be used to cause roots to developCan be used to cause roots to develop
Expands the list of plants that can be Expands the list of plants that can be propagated from cuttingspropagated from cuttings
35Asexual Reproduction in Plants
36Reproduction iReproduction in Plantsn Plants
Tissue Culture of PlantsTissue Culture of PlantsTissue culture is the growth of a tissue in Tissue culture is the growth of a tissue in an artificial liquid or solid culture an artificial liquid or solid culture mediummediumPlant cells are totipotentPlant cells are totipotent
Meristem cultureMeristem cultureAuxins and cytokinins allow many new Auxins and cytokinins allow many new shoots to develop from a single shoot tipshoots to develop from a single shoot tipVirus-free clonal plantsVirus-free clonal plants
Suspension CultureSuspension CultureRapidly growing calluses are cut into small Rapidly growing calluses are cut into small pieces and shaken into a liquid nutrient pieces and shaken into a liquid nutrient mediummediumSingle cells or small clumps break off and Single cells or small clumps break off and form a suspensionform a suspension
37Tissue Culture in Plants
38Reproduction iReproduction in Plantsn Plants
Genetic EngineeringGenetic EngineeringTraditionally, hybridization was used to Traditionally, hybridization was used to
produce plants with desirable traitsproduce plants with desirable traits
Crossing different varieties of plantsCrossing different varieties of plants
Transgenic plants can now be produced Transgenic plants can now be produced by placing foreign genes into a plantby placing foreign genes into a plant
Agricultural plants with improved Agricultural plants with improved traitstraits
Pest or insecticide resistantPest or insecticide resistant
Commercial ProductsCommercial Products
Human hormones, antibodiesHuman hormones, antibodies
39Maize
40Genetically Engineered Plants
41Reproduction iReproduction in Plantsn Plants
ReviewReview
Reproductive StrategiesReproductive StrategiesAlternation of generationsAlternation of generationsAdaptation to a land environmentAdaptation to a land environmentFlowersFlowersPollinationPollination FertilizationFertilization
Seed DevelopmentSeed DevelopmentFruitFruitSeed GerminationSeed GerminationAsexual ReproductionAsexual ReproductionTissue CultureTissue Culture
Reproduction in Plants
Ending Slide Chapter 28