Asexual reproduction algae

Coenobium

1) biflagellate zoospores form after meiotic division

2) release zoospores through vesicle

3) expand free vesicle

4)arrange into daughter coenobia

Phycoma

Pyramimonadales aplanospores

resistant, cyst-like structures

eg: Halosphaera: spring/early summer accumulates in waters creating green oily blooms

Charophyceae

fragmentation + bulbils

specialised nodules in rhizoidal region

survive unfavourable conditions

zoospores with polysaccharide scales

Coleochaetophyceae

Mitosis-Cytokinesis

unicellular Zygnematophyceae

unicellular chlorophyta

Fragmentation of thallus

filamentous Zygnematophyceae

Charophyceae

Zygnema fibre fragmentation

good adaptation for spreading, for example, by wind after the puddle dries up

Cymopolia when thallus disturbed (2)

Dasycladales

asexual reproduction

thallus can arise from fragments or gametangia that were not released before segment calcifies

Penicillus vegetative propagation

Bryopsidales

via stolons

Trentepohlia hook shaped cells

Asexual zoospores are produced inside structures called zoosporangia. These sporangia are attached to the main filament via a highly modified, crooked, or hook-shaped stalk cell

unique hook shape plays a key role in dispersal. When environmental moisture is present, the hook-shaped suffultory cell mechanically responds and straightens out. This action lifts and pushes the sporangium away from the main algal body, allowing it to snap or break off smoothly (abscission) to promote windborne or waterborne dispersal

Ulothrix asexual production (4)

haplontic

dividing entire protoplast into tetraflagellate zoospores

emerge and attach to the substrate with apical part

forms attachment disc and grow into filament

Ulvales gametes when no compatible partner found

attach and give rise to gametophyte again

Ulva/Enteromorpha asexual reproduction

occurs mainly by fragmentation of thallus

Kirchneriella reproduction (4)

Chlorophyceae

autospores,

which are formed in fours in the mother cell wall

(two are formed first and then divide once more).

Pediastrum asexual reproduction (6)

formation of new daughter coenobia.

cytoplasm division occurs, during which a precisely defined number of zoospores are formed, which are released into the environment in the mucus sac.

The zoospores swarm for a while in it and organize themselves into a new daughter coenobia.

Finally, they shed their flagella and change their morphology.

The whole process takes only a few minutes.

The coenobia then just grows, but does not change its number of cells

Hydrodictyon reticulatum asexual reproduction (7) CHlorophyceae

A new daughter coenobium can arise in each cell of the cenobia.

By dividing the cytoplasm, a large number of zoospores with a predefined number are created, which are arranged in a new future coenobium.

Then they shed their flagella, change their morphology and, after rupturing the mother cell, are released into the environment.

The coenobium is initially small, but gradually grows to the size of the mother coenobium.

The second method of asexual reproduction consists in the release of a zoospore from the coenobium cell and the formation of a primary hypnozygote.

From it, a zoospore then emerges again, which creates a secondary hypnozygote in the shape of polyhedron.

In it, the cytoplasm is grooved and a package of zoospores is formed, which are then organized into a new coenobium after being released from the hypnozygote

Microspora asexual reproduction Chlorophyceae

 by fragmentation or by biflagellated zoospores, which are released by the breakdown of filaments. Akinetes are formed by the thickening of the cell wall layers.

Chlamydomonas asexual reproduction

occurs by longitudinal cell division

Chlorella reproduction (4)

autosporulation

contents of cell divide into 2,4, or sometimes 8 protoplasts

liberated by rupture of parent cell wall, each autospore becomes new individual

daughter cell may remain attached to parent cell wall, forming colony of cells

Trebouxia asexual reproduction

4-32 autospores or zoospores

Asterochloris autosporogenesis

much larger quantity of planospores/zoospores (64 or 128)