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BOT 306 > Lichens > Flashcards

Lichens Flashcards

1
Q

Which pathways are we certain that symbionts do NOT make contact with in lichens?

A

CSSP and MiSSP7

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2
Q

What is the narrative surrounding lichens?

A

A fungus co-occurs with one or more algae/cyanobacteria

The alga provides sugars for use by the fungus

The fungus provides a regulated environment that optimizes algal growth

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3
Q

What do real lichens look like?

A

Biophysical properties: dry = some brittle, some flexible; moist = specific torsion. elasticity, flexibility

Shape: flat, round

Water relations: ability to take up or get rid of water

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4
Q

Where are yeasts in lichen typically found?

A

In the polysaccharide layer that coats the lichen

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5
Q

Letharia lichens consistently contain which 3 fungi?

A

Hyphal ascomycete
Two basidiomycete yeasts

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6
Q

How have the overlooked fungi been missed?

A

Primer bias
Insufficient sequencing coverage

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7
Q

What is primer bias?

A

Primers are made with a priori knowledge
Can’t make a primer for something you cannot see or do not know exists

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8
Q

What are fungi cemented together by in lichens?

A

An extracellular polysaccharide layer

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9
Q

What is the EPS made of?

A

Ascomycetes: maybe galactomannans

Basidiomycetes: maybe GXM exo-polysaccharides

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10
Q

What are the visual points of reference for polysaccharides?

A

Lectin-based localization
Direct analysis of monosaccharide profiles

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11
Q

What are the GXM motifs?

A

Mannose
Glucuronic acid
Xylose
Fucose

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12
Q

Which fungi produce GXM?

A

Tremellaceae like snow fungus

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13
Q

What breaks down GXM in nature

A
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14
Q

Lichens have what?

A

Numerous high-frequency symbionts that easily escape detection

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15
Q

What is the most common lichen symbiont worldwide?

A

Acetobacteraceae tie with or surpass Trebouxiaceae algae as the most common

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16
Q

How many bacterial families are on par with algae in frequency?

A

4

17
Q

What is the frequency of Cystobasidiomycetes?

A

They are found in at least 1/3 of Tremellomycetes and 2/3 of lichen metagenomes

18
Q

Cyanobacteria sugar assimilation?

A

Glucose assimilates into mannitol and arabitol

19
Q

Trentepohlia sugar assimilation?

A

Erythritol assimilates into erythritol

20
Q

Trebouziophyceae sugar assimilation?

A

Ribitol assimilates into mannitol and arabitol

21
Q

What are some early lichen goods exchange observations?

A

Lichens lose considerable amounts of polyols during wetting-drying cycles
Much of the cellular carbon uptake in the fungus is kept in a soluble fraction
Most lichens do not grow much

22
Q

Why are lichens not great lab models?

A

They grow extremely slow

23
Q

What mutualism arose from gene loss?

A

Saprotrophs evolved into mycorrhiza

24
Q

Almost all orphan lineages of lichens descend from what?

A

A common ancestor

25
Q

The members of the orphan lineage clade have what?

A

Some of the smallest degradative CAZyme arsenals in Ascomycota

26
Q

Lichen fungal symbionts from the Dothideomycetes have what?

A

Some of the largest degradative CAZyme arsenals

27
Q

Does symbiosis with an alga predict CAZyme and transporter arsenal size?

A

No, there is a range

28
Q

When should lichen have a genomic signal for PCWDEs?

A

If lichen fungi are getting carbon from other sources, fungal symbionts from lichens with strong organic substrate preferences should have this

29
Q

Why are non-reducing sugars Janus carbohydrates?

A

They have two uses: growth/respiration and protection

30
Q

What is the support for nutritional symbiosis?

A

CO2 exchange and CHla content are correlated in whole lichens

Chla content and relative growth rate are correlated in whole lichens

31
Q

What do mycorrhizal genomes exhibit following glucose subsidy?

A

Loss of CAZymes

32
Q

What do lichen fungi exhibit a greater range of than ectomycorrhizae?

A

CAZyme arsenals

33
Q

CAZyme arsenal size varies with what?

A

The type of photobiont export

34
Q

What is the future direction for lichen research?

A

Does the duel function of polyols drive the evolution of slow growth?

If the polyol pool is needed for survival, there would be costs that use this pool for growth

BOT 306 (16 decks)

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