Plant and FungiReproduction

Campbell 9th Ed

Chapter 38- PlantsChapter 31- Fungi

Outline

Formation of Angiosperm Gametes Pollination

– Self Pollination Fertilization Life Cycle of Plants Life Cycle of Fungi

Four main groups of plants Moss- No vascular tissue, no

seeds Fern- Vascular tissue but no seeds Gymnosperm- Vascular tissue and

seeds (ex: pine tree) Angiosperm- Flowering Plants-

Vascular Tissue, Seeds and Flowers

All this reflects evolution from ___ to ___

What’s weird about plant life cycles?

Alternation of generations

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2n

2n

Egg

MitosisSpore

2n

Sporophyte(2n)

Sporangia

Spore mothercell

Sporesn

nn

n

Gametophyte(n)

Gamete fusion

Sperm

Embryo

Zygote

Meiosis

Haploid

Diploid

What that looks like in a fern…

18

Typical Fern Lifecycle

Angiosperms

Pathways to Flower Production Genetically regulated flowering

pathways– light-dependent

short-day plants long-day plants day-neutral plants

– temperature-dependent vernalization - period of chilling

Structures- Shown on next slide Female Structures.

– single or fused carpels also referred to as simple or compound pistils

ovules produced in pistil’s swollen ovary– style - slender neck– stigma – pollen receptive structure

Male Structures– Stamen- male structures

Anther- pollen producing Filament – stalk

Angiosperm Flower

Alternation of generations in an angiosperm.

Formation of Angiosperm Gametes * All plant sexual life cycles are

characterized by an alternation of generations.– Diploid sporophyte gives rise to haploid

gametophyte generation. Male gametophytes - Pollen grains-

microspore Female gametophyte - Embryo sac-

megaspore

*This is to help you understand the next diagram, but not in the scope of testing.

Formation of Angiosperm Gametes

Pollen Formation– Microspore mother cells are microspore

producing cells Microspores make sperm (Megaspores are

female)– Each pollen sac contains specialized

chambers enclosing microspore mother cells.

Undergo meiosis to form four haploid microspores.

– Pollen grain shapes are specialized for specific flower species.

– Pollen of some plants causes hypersensitivity response in some people.

Formation of Angiosperm Gametes *

Embryo Sac– Megaspore mother cell found within each

ovule. Undergoes meiosis to produce four haploid

megaspores.– Usually only one survives and the other three are

absorbed by the ovule. Remaining megaspore undergoes mitosis and

produces eight haploid nuclei enclosed in an embryo sac.

– *This is to help you understand the next diagram, but not in the scope of testing.

Pollen Grain and Embryo Sac Formation

Fertilization

Double Fertilization results in two key developments:– Fertilization of the egg.– Formation of endosperm.

Pollen grains adhere to the stigma and grow a pollen tube that pierces the style.– Grows until it reaches the ovule in

the ovary.

Pollen Tube Formation and Fertilization

Alternation of Generations and Fitness By alternating, plants can

continue their life cycle even when there is no reproductive partner.

Spores resist adverse conditions such as drought, extreme heat, and extreme cold.

Moss and ferns rely on water for their swimming sperm

Alternation of generations in an angiosperm.

36

Typical Angiosperm Lifecycle

Diploid

Haploid

Seasonal Reproduction Plants in N. America can time

their reproduction to give them the best chance of reproductive success.

Some angiosperms are biennial. They take two years to go through one cycle. This may allow them to become hardier. (They can also change this timing in response to environment).

Diapause- becoming dormant in adverse conditions.

Fungi

The Body of a Fungus

Fungi exist mainly in the form of slender filaments (hyphae).– long chains of cells joined end-to-

end divided by cross-walls (septa) rarely form complete barrier cytoplasm freely streams in hyphae

– mycelium - mass of connected hyphae

grows through and penetrates substrate

What’s weird about fungi reproduction?

How Fungi Reproduce Differ from most animals and plants in

that each compartment of hypha can contain one, two or more nuclei– monokaryotic - each compartment has a

single nucleus– dikaryotic - two distinct nuclei within each

hyphae compartment

How Fungi Reproduce Fungi are capable of both sexual and

asexual reproduction.– Fungi reproduce sexually after two hyphae

of opposite mating type fuse. Some fungi have dikaryotic stage (1n + 1n)

before parental nuclei fuse to form diploid nucleus

Ascomycota

Sordaria- Remember this slide from the meiosis lab? You are looking at a

fungus, Sordaria The structures you see are

called asci (ascus- singular), they are the product of meiosis.

Count 50 asci. Tally the number that show crossover/ no-crossover.

Divide the crossover frequency by 2 to get map units (centimorgans).

Basidiomycota

Metabolic Pathways of Fungi Anaerobic fermentation provides

flavor for wine and cheese. Biochemical manufacturing of

organic substances– food– pharmaceuticals

Yeasts break down carbon-containing products.– bioremediation

Ecology of Fungi

Fungi and bacteria are the principal decomposers in the biosphere.– mineral cycling

Fungi are virtually the only organisms capable of breaking down lignin- (found in wood).

Fungi often act as disease-causing organisms for both plants and animals.– agricultural damage- corn rust (also

wheat rust, rye rust), potato blight– human health

Ecology of Fungi

Mutualistic associations– lichens - fungi and green algae

Mutual relationship Primary succession

– mycorrhizae - fungi and plant roots Mutual relationship- may be food protection Fungi on root may help plant absorb

water/ minerals

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