Plant Reproduction II

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Plant Reproduction II

• Roses are red,
• Violets are blue,
• Some poems rhyme.
• But this one doesn't.
• - anonymous

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Business

• Quiz Wednesday,
• Essay Questions due Weds. Midnight, 2 pt Extra
  Credit.

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The Tree(s) of LifeKwakwakawakw

• Western Red cedar
• (Thuja plicata)
• and -
• Alaska cedar/ Yellow cedar
• (Chamaecyparis nootkatensis)

Thuja plicata
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The Tree(s) of LifeKwakwakawakw

• Western Red cedar
• (Thuja plicata)
• and -
• Alaska cedar/ Yellow cedar
• (Chamaecyparis nootkatensis)

Chamaecyparis nootkatensis
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• "In a small clearing in the forest, a young
  woman is in labour.  Two women companions urge
  her to pull hard on the cedar bark rope tied to a
  nearby tree.  The baby, born onto a newly made
  cedar bark mat, cries its arrival into the
  Northwest Coast world.  Its cradle of firmly
  woven cedar root, with a mattress and a covering
  of soft-shredded cedar bark, is ready. The young
  woman's husband and his uncle are on the water in
  a canoe carved from a single red cedar log and
  are using paddles made from lengths of yellow
  cedar. Wearing a cedar bark hat, cape and skirt
  to protect her from the rain and cold, the baby's
  grandmother collects berries.  She loads them
  into a basket of cedar root and adjusts the broad
  cedar tumpline across her forehead and returns
  home.
• The embers in the centre of the cedar house
  leap into flame as the grandmother's niece adds
  more wood.  Smoke billows past the cedar rack
  above, where small fish are hung to cure. The
  young girl takes red-hot rocks from the fire with
  long tongs, dips them into a small cedar box of
  water to rinse off the ashes, then places the
  rocks into a cedar wood cooking box to boil
  water.  The young girl then coils two fresh
  diapers from soft-shredded cedar bark and goes to
  tend a crying baby, while the child's father
  prepares long, slender cedar withes to lash a
  stone hammer to. With the hammer finished he uses
  it to pound wedges into a cedar log to split off
  a plank for a tackle box to fit in bow of his
  canoe."

Hilary Stewart's Cedar tree of life to the
Northwest Coast Indians (1984)
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• Look at me friend! I come to ask for your
  dress For you have pity on us For there is
  nothing for which you cannot be used...For you
  are really willing to give us your dress, I come
  to beg you for this, Long-life maker For I am
  going to make a basket for camus-roots out of you.

Kwakwakawakw prayer
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Secondary Growth
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(No Transcript)
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Today

• Spore formation,
• Gamete formation,
• Pollination,
• Fertilization,
• Germination.

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Spore Formation Study Fig 40.8
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Pollen Development(male gametophyte)
Fig 40.8
meiosis
mitosis
microspores ...meiosis yields four haploid
cells,
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Pollen Cells
Lily
Sperm
Tube Cell forms the pollen tube, Generative
cell forms two sperm (mitosis),
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Pollen
Horse Chestnut
Lily
Lily Close-up
Ragweed

• Outer wall is formed primarily of sporopollenin,
• and proteins (mating signals?),
• Form adapted for specific pollinators,
• Species specific, durable.

• Well represented in the fossil, prehistoric and
  historic record,
• Used for environmental and ecological studies,
• Used for forensic work.

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(No Transcript)
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Embryo Sac Development( female gametophore)
Fig 40.14
meiosis
mitosis
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Embryo Sac Development( female gametophyte)
megasporocytes
ovules
embryo sac
integument
megaspore
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Pollination

• the transfer of pollen from an anther to a
  stigma,
• does not imply fertilization,
• Vector,
• the means of transfer.

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Pollinationvectors
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Pollinationvectors
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Pollination / Speciation

• Differences in alpine skypilot populations are
  due to differential selection by pollinators.

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Anthers / Dehiscence
Pollen Sacs
Dehiscence pollen sacs break, pollen is
released.
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Self-Fertilization

• acceptable in some species,
• prohibited in others,
• dioecious plants,
• moneocious plants with timing differences,
• structural (i.e pin and thrum),

• S alleles (genetic compatibility).

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Self Incompatibility
Box 40.2

• Alleles alternate versions of a gene,
• diploid organism have two copies of every gene
  (one from mom, one from dad),
• in a population, many alleles may be present.

• S genes self-compatibility genes,
• genes whose products block fertilization by
  like individuals,
• S-locus the genomic location of the S genes.

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Self Incompatibilitymodes

• Gametophytic (pollen)
• blocking process occurs within the pollen,
• i.e. incompatible (self) pollen allows the import
  of RNA degrading enzymes,

• Sporophytic (stigma),
• carpel tissue blocks pollen function,

E (effector) protein blocks pollen function.
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Pollen Germination

• Metabolic rates are low in pollen grains,
• Germination,
• tube cell tip growth under proper stimuli,
• Tubes of cytoplasm form and lengthen allowing the
  movement of sperm nuclei.

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Pollen Tube
http//www.bio.umass.edu/hepler/Images_movie_2.htm
Guided by stigmatic signals, not by environmental
cues.
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Pollen Tube Growth Double Fertilization
Fig 40.14
Generative cell divides ...to become two sperm
nuclei in the pollen tube,
Pollen germinates pollen tube begins to grow
down style,
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Lilium
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Embryo Sac Development( female gametophore)
embryo vasculature forms and primary meristems
are established.
daughter cells divide into a mass of cells
(proembryo), and a string of single cells
(suspensor),
Fig 40.15
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See Fig 40.16
Embryo Development storage

• Endosperm nuclei (3n) divide forming rich
  nutritious material,
• cytokinesis follows and partitions the nuclei
  between membranes,
• most dicots absorb the nutrient of the endosperm
  into their cotyledons before germination,

• most monocots (and some dicots) use endosperm
  after the seed germinates,

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Fruit maternal
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Today

• Spore formation,
• Gamete formation,
• Pollination,
• Fertilization,
• Germination.

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Dormant Seeds

• Dormancy slow metabolic rate and suspension of
  growth and development,
• seed coat dormancy (seed coat impermeable to O2
  and H2O),
• release by scarification (fire, abrasion,
  digestive tracts, etc.),
• internal dormancy (physiological),
• the most common internal dormancy is a
  requirement for cold,
• release by stratification (cold treatment).

Know these terms.
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Seed Germinationphase changes

• Dormant to metabolically active,
• etiolated growth (dark growth),
• respond to gravity,
• light,
• temperature,
• touch,
• De-etiolation (dark to light habit),
• vegetative growth program.

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Home Stretch

• Responses to internal and external signals are
  studied (to a large extent) by studying the
  genetics and physiology of...

Germination (phase change) Etiolated
Growth De-etiolation (phase change)
Signal Transduction Hormones Photomorphogenesis Gr
avitropism others...