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B3.0 > Leaf Development And Evolution II: Polarity, Boundaries And Axes > Flashcards

Leaf Development And Evolution II: Polarity, Boundaries And Axes Flashcards

1
Q

Phyllotactic patterns in angiosperms

A

1) alternate
2) opposite
3) whorled
4) spiral

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2
Q

Spiral phyllotaxy in seed plants under SEM

A
  • dome = S.A.
  • protrusions = leaves
  • pattern is shrinking
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3
Q

Phytomers

A

1) leaf
2) axillary bud
3) internode
- iterative development
- specific arrangement

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4
Q

Monocot phytomer

A
  • leaf blade @ top
  • different order
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5
Q

S. kraussania

A
  • dichotomous branching: specifically patterned major and minor branches
  • ventral and dorsal leaf pairs w/ specific rhizophores
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6
Q

S. kraussania shoot patterning

A
  • how to generate 6/8 leaves?
  • 2 cells on A surface act as stem cells
  • meristem bifurcates
  • 4x growth axes; DV, LR, 2x diagonal
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7
Q

LR S. kraussania

A

How does meristem bifurcate?

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8
Q

Fern shoot development

A

1) tetrahedral shoot initial
2) frond initial
3) pinna initial

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9
Q

Older primordia specify leaf position

A
  • anatomically distinguishable from S.A. flanks
  • isolate I1 from apex by incision
  • I3 develops closer to I2 than usual
  • mechanical constraint? Biochemistry? Combinatorial?
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10
Q

abphyll

A

2x P3 leaves

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11
Q

NPA

A
  • auxin analog
  • binds to PATs and doesn’t detach
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12
Q

Leaf initiation under NPA

A
  • SAM becomes pin-shaped
  • no leaf initiation from flanks
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13
Q

pin1

A
  • SAM becomes pin-shaped
  • no leaf initiation from flanks
  • auxin: rescue
  • lanolin control
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14
Q

Auxin:

A
  • IAAH, IAA- (protonation states)
  • cell wall/apoplast (5.5): IAAH
  • diffuses through lipid bilayer to enter cytoplasm
  • cytoplasm (7): IAA-
  • stuck!
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15
Q

PIN polarity creates

A

Auxin I1 maxima

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16
Q

PIN polarity aligns w

A
  • microtubule orientation
  • stress, for support
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17
Q

Ablating stressed cells with a laser

A

PIN moves away

18
Q

Leaf axes

A

1) proximo-distal
2) medio-lateral

19
Q

What determines axes in a leaf?

A
  • when a leaf is developing, axes info comes from the shoot
  • once a leaf is specified, it is all there
20
Q

Explant P1

A
  • develops as a leaf
21
Q

Explant I1 and I2

A

Develop as shoots

22
Q

Remove all leaves

A

I1 develops as leaf

23
Q

Features of adaxial-abaxial leaf axis

A
  • stomata (abaxial abundance)
  • xylem (adaxial)
  • phloem (abaxial)
  • adaxial faces towards meristem
  • abaxial faces away
24
Q

PHABULOSA and KANADI

A

2x important TFs for adaxial-abaxial specification

25
Q

recessive kanadi triple KO: kan1-2, 2-3, 3-1

A
  • adaxialised
26
Q

recessive phabulosa triple KO: rev-9, phb-6, phv-5

A
  • abaxialised
  • ## phloem encircles xylem
27
Q

REVOLUTA, PHABULOSA, PHAVOLUTA

A

Class III HD-ZIP family

28
Q

dominant phabulosa

A

Adaxialised?

29
Q

PHB primordial expression by in situ hybridisation

A
  • detect gene transcript thru colourimetric reaction
  • P2: ubiquitous
  • P6: adaxialised
30
Q

PHB regulation

A
  • PHB mRNA: adaxial
  • miRNA165/166: abaxial
  • dominant phb mRNA: ubiquitous because miRNA can no longer bind
31
Q

KANADI

A

induce GARP TFs

32
Q

KANADI expression

A
  • transverse and longitudinal sections of v young leaves
  • abaxialisation
33
Q

stm1

A
  • no SAM
  • KNOX LOF
34
Q

cuc1, cuc2

A
  • no SAM
  • fused cotyledons
  • NAC domain TFs
35
Q

STM and CUC2 expression

A
  • STM repressed in cuc1, cuc2
  • CUC2 similar expression to wt in stm
36
Q

STM and CUC feedback regulatory loop

A
  • STM defines meristematic region
  • STM prevents CUC localisation
  • CUC defines borders of meristematic region
  • need both in a functioning meristem
37
Q

wox

A
  • narrow leaf phenotype
  • lamina don’t expand @ base
38
Q

wox3

A
  • thin blade
  • does not establish marginal region
  • no KNOX in SAM
39
Q

How is the margin defined?

A

Suppression of KNOX accumulation

40
Q

WOX

A
  • WUS-like
  • expands leaf
  • defines middle of adaxial-abaxial axis
41
Q

WOX mechanism

A
  • promotes auxin biosynthesis @ leaf margins ; growth agonist
  • increased expression at base; higher growth rate
  • decreased expression at tip; higher differ mention

B3.0 (23 decks)

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