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B3.0 > Improving Submergence + Waterlogging Tolerance > Flashcards

Improving Submergence + Waterlogging Tolerance Flashcards

1
Q

Natural strategies to improve submergence

A

Happen @ different developmental stages
-> germination
-> stems
-> leaves

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2
Q

Anaerobic germination

A
  1. Wheat
  2. Barley
  3. Maize
  4. Oat
  5. Rice
  6. E. crus-galli (rice weed)
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3
Q

Anaerobic germination mechanism

A
  • rapid coleoptile extension + emergence; “snorkel”
  • oxygen stimulus permits shoot and root emittance
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4
Q

Normal condition for germination

A
  • embryo induces alpha-amylases in aleurone layer via GAs
  • high sugar levels inhibit amylase expression
  • manages starch consumption (speed, availability)
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5
Q

Anoxia condition for germination

A
  • rice: GA-independent α-amylase induction
  • different α-amylase used
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6
Q

Submergence-induced heterophylly

A
  • alternative leaf morphology
  • no epidermal stomata: Raninculus trichophyllus
  • inhibited leaflet expansion: Potamogetol perfoliatus
  • Callitriche protrusions
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7
Q

What causes heterophylly?

A
  • light quality: Rorippa aquatica
  • temperature: Hygrophila afformis
  • humidity
  • all of these are controlled by hormones
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8
Q

Leaf gas films

A
  • an hydrophobic surface generates a GES around/above the leaf
  • adaptive to non-continuous flooding
  • ^ underwater photosynthesis
  • volume around lead where photosynthesis & respiration can still occur
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9
Q

What makes a leaf impermeable?

A
  • study different accessions for hydrophobicity
  • Kinmaze: maintains LGFs one day post-submergence
  • drp7: does not
  • different wax cuticle compositions
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10
Q

Hypoxia avoidance

A
  • rapid elongation for emersion
  • deep water rice: rapid internode elongation on submergence
  • several ms
  • limited exploitability in agriculture
  • consumes reserves (< yield)
  • induces lodging
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11
Q

aerenchyma

A
  • “snorkel”
  • root and shoot tissues can develop hollow cavities to enhance gas transfer from aerial -> submerged tissues
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12
Q

Barriers to ROL

A
  • progressive oxygen impermeabilisation accompanies aerenchyma formation
  • enhances SAM delivery
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13
Q

ROL

A

radial oxygen loss

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14
Q

Without Suberin

A
  • cell wall is porous (3.5-5.2nm)
  • H2O, salts, gases interchange
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15
Q

Suberin lamellae

A
  • highly hydrophobic (oxygen impermeable)
  • lignin-like aromatic elements connect suberins to lignin
  • accumulate under submergence
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16
Q

Adventitious roots

A
  • from the stem
  • sustain aeration, nutrient acquisition, growth
17
Q

Sub1 locus

A
  • 0.06cM
  • 120kb
  • 8 genes
  • submergence tolerance
18
Q

Sub1 trait segregation

A
  • rice = diploid
  • Oryza sativa indica FR13A: flood tolerant (3x ERFVIIs: Sub1a, Sub1b, Sub1c)
  • cross with O. sativa japonica M-202: flood-intolerant donor
  • F1 = flood tolerant
  • self pollination
  • F2 = (in)tolerant ; even distribution of molecular markers across different chromosomes
19
Q

Sub

A

Submergence-induced

20
Q

Sub1a

A
  • FR13A: yes
  • Nipponbare (intolerant): no
  • to prove: KI, KO
21
Q

How does Sub1a induce tolerance

A
  • Sub1a donor (IR4D931-26): restricted growth
  • O. sativa japonica Liaogeng (intolerant) + constitutive expression = sufficient
22
Q

Restricted growth =

A

Decreased submergence elongation

23
Q

Sub1a induces DELLA

A

Energy-saving, quiescence

24
Q

Submergence pathway

A

Sub1a activates SLR1/SLR2 (DELLA), blocks GA (shoot elongation, CHO consumption)

25
Q

GWAS

A
  • identifying useful genetic loci
  • barley accession germination times after short term submergence differs
  • > 200 accessions associated with specific SNP round Laccase gene
26
Q

Laccase

A

Lignin polymerisation

27
Q

Is the LAC gene responsible for less germination post-submergence?

A
  • not in exonic regions
  • differential expression @ developmental stage 4 in tolerant and sensitive
  • deletions in promoter region
28
Q

Expressing LAC

A
  • ^ seed coat lignification (stain w lignin bind)
  • < O2 diffusion -> embryo
  • < germination capacity, no seed scarification
29
Q

Manipulate O2 sensitivity to ^ hypoxia tolerance in crops?

A
  • e.g. Arabidopsis PCO4
  • enzyme engineering / gene editing
  • variant testing in vitro/ in vivo
  • crop translation
30
Q

Enzyme engineering approaches

A

1) structure-guided varietal design
2) random mutagenesis
3) directed evolution

31
Q

Anaerobic germination in cereals?

A
  • rewire existing α-amylases for hypoxia induction
  • barley, wheat
32
Q

Rice anaerobic germination?

A
  • GAMYB TFs increase sugar to meet demand
  • can we subjugate to O2 sensing pathway as a chimera?
33
Q

Rice anaerobic germination?

A
  • GAMYB TFs increase sugar to meet demand
  • can we subjugate to O2 sensing pathway as a chimera?

B3.0 (23 decks)

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