CHAPTER 38
Download
1 / 50

CHAPTER 38 PLANT REPRODUCTION - PowerPoint PPT Presentation


  • 103 Views
  • Uploaded on

CHAPTER 38 PLANT REPRODUCTION. Angiosperm Reproduction & Biotechnology. Floral Organs. Sepals and petals are nonreproductive organs. Sepals : enclose and protect the floral bud before it opens; usually green and more leaf-like in appearance.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' CHAPTER 38 PLANT REPRODUCTION' - marlo


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

CHAPTER 38 PLANT REPRODUCTION

Angiosperm Reproduction & Biotechnology



Sepals and petals are nonreproductive organs.

Sepals: enclose and protect the floral bud before it opens; usually green and more leaf-like in appearance.

In many angiosperms, the petals are brightly colored to attract pollinators.


Stamens: male reproductive organs

  • Stalk: the filament

  • Anther: pollen sacs.

    • The pollen sacs produce pollen.


Carpels: female reproductive organs

Ovary- base of the carpel

Ovules

Egg cell

Embryo Sac (female gametophyte), i.e., seed

Stigma- platform for pollen grain

Style- slender neck, connects ovary and stigma


The stamens and carpels of flowers contain sporangia, within which the spores and then gametophytes develop.

The male gametophytes are sperm-producing structures called pollen grains, which form within the pollen sacs of anthers.

The female gametophytes are egg-producing structures called embryo sacs, which form within the ovules in ovaries.


Pollination begins the process by which the male and female gametophytes are brought together so that their gametes can unite.

Pollination- when pollen released from anthers lands on a stigma.

Each pollen grain produces a pollen tube, which grows down into the ovary via the style and discharges sperm into the embryo sac, fertilizing the egg.

The zygote gives rise to an embryo.

The ovule develops into a seed and the entire ovary develops into a fruit containing one or more seeds.

Fruits disperse seeds away from the source plant where the seed germinates.


Function of flowers
Function of Flowers gametophytes are brought together so that their gametes can unite.


Classification of flowers

Complete Versus Incomplete Flowers gametophytes are brought together so that their gametes can unite.

Complete: possess sepals, petals, stamens, and carpels

Incomplete: lack one or more of these components

Perfect Versus Imperfect Flowers

Perfect: possess both stamens and carpels

Imperfect: possess either stamens (staminate) or carpels (carpelate), but not both

Classification of Flowers


Complete flower
Complete Flower gametophytes are brought together so that their gametes can unite.


Monoecious versus dioecious

Monoecious: gametophytes are brought together so that their gametes can unite. both staminate and carpellate flowers are found together on the same plant (e.g., corn).

Dioecious: staminate flowers occur on separate plants from those that carry carpellate flowers (e.g., date palms).

Monoecious Versus Dioecious


Monoecious
Monoecious gametophytes are brought together so that their gametes can unite.


Dioecious
Dioecious gametophytes are brought together so that their gametes can unite.


Angiosperm life cycle
Angiosperm Life Cycle gametophytes are brought together so that their gametes can unite.



The male gametophyte begins its development within the sporangia (pollen sacs) of the anther.

Within the sporangia are microsporocytes, each of which will from four haploid microspores through meiosis.

Each microspore can eventually give rise to a haploid male gametophyte.


A microspore divides once by mitosis and produces a sporangia (pollen sacs) of the anther.generative cell and a tube cell.

The generative cell forms sperm.

The tube cell, enclosing the generative cell, produces the pollen tube, which delivers sperm to the egg.


Pollen tubes
Pollen Tubes sporangia (pollen sacs) of the anther.


Pollen grains
Pollen Grains sporangia (pollen sacs) of the anther.

  • This is a pollen grain, an immature male gametophyte.


Barriers to self fertilization
Barriers to Self-Fertilization sporangia (pollen sacs) of the anther.

  • Stamens and carpels may mature at different times.

  • Self-incompatibility- plant rejects its own pollen

  • Plant design prevents an animal pollinator from transferring pollen from the anthers to the stigma of the same flower.


The genetic basis for the inhibition of self fertilization
The Genetic Basis for the Inhibition of Self-Fertilization sporangia (pollen sacs) of the anther.

  • S-genes: self-incompatibility gene

  • If a pollen grain and the carpel’s stigma have matching alleles at the S-locus, then the pollen grain fails to initiate or complete the formation of a pollen tube.


Pollen tube formation and double fertilization
Pollen Tube Formation and Double Fertilization sporangia (pollen sacs) of the anther.


Seed development
Seed Development sporangia (pollen sacs) of the anther.


Release of sugars from the endosperm during germination sporangia (pollen sacs) of the anther.


embryo sporangia (pollen sacs) of the anther.

endosperm


Fate of the endosperm

Typical Monocot (e.g., corn) sporangia (pollen sacs) of the anther.

endosperm present in substantial quantities in mature seed.

cotyledon absorbs nutrients from endosperm during seed germination.

Typical Dicot (e.g, garden bean)

endosperm completely absorbed into cotyledons before seed maturation.

Other Dicots (e.g., castor bean)

endosperm only partially absorbed by cotyledons during seed maturation.

remainder of endosperm absorbed by cotyledons during germination.

Fate of the Endosperm


Seed structure
Seed Structure sporangia (pollen sacs) of the anther.


Relationship of the flower to the fruit
Relationship of the Flower to the Fruit sporangia (pollen sacs) of the anther.


The ovary develops into a fruit adapted for seed dispersal

As the seeds are developing from ovules, the ovary of the flower is developing into a fruit, which protects the enclosed seeds and aids in their dispersal by wind or animals.

Pollination triggers hormonal changes that cause the ovary to begin its transformation into a fruit.

If a flower has not been pollinated, fruit usually does not develop, and the entire flower withers and falls away.

The ovary develops into a fruit adapted for seed dispersal


Fruit Formation flower is developing into a fruit, which protects the enclosed seeds and aids in their dispersal by wind or animals.

The ovary wall becomes the pericarp, the thickened wall of the fruit

Other flower parts wither and are shed.

However, in some angiosperms, other floral parts contribute to what we call a fruit.

Development of a pea fruit (pod)


Functions of the fruit

Protection of the enclosed seed (e.g., pea pods). flower is developing into a fruit, which protects the enclosed seeds and aids in their dispersal by wind or animals.

Facilitating dispersal.

wings for wind dispersal (e.g., maple).

hocks and barbs for attachment to animal fur or avian feathers (e.g., cocklebur).

sweet, fleshy fruit encouraging ingestion and dispersal of seeds by animals (e.g., cherry).

Functions of the Fruit


Fig 38 10

Fig. 38-10 flower is developing into a fruit, which protects the enclosed seeds and aids in their dispersal by wind or animals.

Types of Fruits

Stigma

Style

Carpels

Petal

Stamen

Flower

Ovary

Stamen

Stamen

Sepal

Stigma

Ovary

(in receptacle)

Ovule

Ovule

Pea flower

Raspberry flower

Pineapple inflorescence

Apple flower

Each segment

develops

from the

carpel

of one

flower

Remains of

stamens and styles

Carpel

(fruitlet)

Sepals

Stigma

Seed

Ovary

Stamen

Seed

Receptacle

Pea fruit

Raspberry fruit

Pineapple fruit

Apple fruit

(a) Simple fruit

(b) Aggregate fruit

(c) Multiple fruit

(d) Accessory fruit


Seed dormancy

Function: allows seeds to germinate at the most optimal time.

Length of dormancy

Signals triggering the end of dormancy.

occurrence of water

period of cold temperature

fire

light

scarification

Seed Dormancy







Asexual propagation of plants in agriculture

Shoot or stem cuttings generate roots. Plants

Cloning from single leaves.

Potato eyes used to generate whole potato plants.

Plant tissue culture.

Grafting.

Asexual Propagation of Plants in Agriculture


Plant Tissue Culture: PlantsPlant biotechnologists have adopted in vitro methods to create and clone novel plants varieties.



Genetic engineering applications of plant tissue culture

Injecting foreign DNA into host cells Plants

Protoplast fusion

Genetic Engineering Applications of Plant Tissue Culture


A dna gun
A DNA Gun Plants


Protoplasts
Protoplasts Plants


Monoculture risks and benefits
Monoculture PlantsRisks and Benefits

Potato blight

Phytophthora infestans

Irish Potato Famine (1845)


Fig 38 18

Fig. 38-18 Plants

Genetically modified rice

Ordinary rice


Ringspot virus Plants

Papya


Make plants disease resistant Plants

Use less pesticides and herbicides

Create plants that are more nutritious

Improve crop yields

Drought resistance

Medicine

Bioengineering

Latest plant developments


Inadvertent consequences: allergies (nuts) Plants

Ethics: patents and ownership of genes

Herbicide tolerance- fear of producing a herbicide resistant weed that could get out of control

Loss of biodiversity

Food safety

Cutting choices for vegetarians

Cross pollination with human food crops

Bioengineering Plants

Risks



ad