Trumpet leaves and microRNA

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Trumpet leaves and microRNA
Catherine Kidner CSHL
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(No Transcript)
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Patterning events happen very early in leaf
development
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Processes in leaf development
Down regulation of meristem-specific genes
Establishment of axis
Growth and cell differentiation
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Stages of leaf development
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Arabidopsis thaliana
flower
silque (fruit)
lateral shoot
cauline leaf
5 Chromosomes 125 Mega bases of DNA First plant
genome sequenced (2001)
rosette leaf
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Patterning events happen very early in leaf
development
Trichome (hair)
Interlocking epidermis
Leaf blade expanding
Petiole
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Genes involved in leaf development
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Mutations in ARGONAUTE1 Cause Developmental
Defects
Relative size
Stem cell defects Organ identity defects Organ
polarity defects
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Mapping Mutations in Arabidopsis
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Populations of Arabidopsis
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Two lab strains
Landsberg
Columbia
Most classical mutants Easiest to transform
originally Compact, so easy to work with
Most new insertion lines Easiest to transform
now Full genome sequence
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CAPs markers exploit the variation between the
two strains
Ler
Col-0
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CAPS mapping
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Wild type siblings
ago-12 phenotype
L/L
L/L
L/L
C/L
C/L
C/C
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The Role of ARGONAUTE
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The ARGONAUTE family
RG-rich
PAZ
PIWI
RG-rich
PIWI
PAZ
Piwi family
AGO family
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An Allelic Series of ARGONAUTE1 Mutants
Strong
Medium
Weak
ago1-12
ago1-11
ago1-9
ago1-10
RG-rich
PAZ
PIWI
RG-rich
PAZ
PIWI
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RNA interference
Centromere function
dsRNA
siRNA
Science 2002
Development
PTGS
Viral defense
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miRNA and the Role of AGO1
AGO1
CAF
RISC
22nt miRNA
miRNA precursor
AGO1
AGO1
aaaaaaa
mRNA
aaaaaaa
mRNA degradation
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AGO1 and Development
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Genes regulated by AGO1
Total RNA
One Step RT-PCR
ER
No Change
AS1
No Change
Down in ago
AG
Down in ago
AP1
Up in ago
CLF
Down in ago
FIL
KAN1
No Change
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AGO1 is required for stem cell function
Strong alleles of AGO1 lack shoot apical meristems
Weak alleles of STM enhance weak alleles of AGO1
ago1-10
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AGO1 is required for organ identity via UFO and
LFY
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ago1-12
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ago1 has Adaxialised Organs
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miRNA Regulation is Required for Stem Cells and
Polarity
Strong caf alleles are embryo lethal
caf-1 (weak)
ago1-11 (weak)
caf/caf, ago1-11/ago1-11
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The HD-ZIP III gene PHABULOSA is Associated with
Adaxial Cell Fate
Phab1-D/
WT
McConnell et al., 1999, 2001
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HD-ZIP III Genes are Targets of miRNA
homeo- domain
START lipid-sterol binding domain
leucine zipper

At REVOLUTA 3 GGCCTGGTCCGAAGTAGG 5 At
PHABULOSA 3 GGCCTGGTCCGAAGTAGG 5 At
PHAVOLUTA 3 GGCCTGGTCCGAAGTAGG
5 At miRNA165 5 CCGGACCAGGCTTCATCC
3 At miRNA166 5 CCGGACCAGGCTTCATCC 3
Reinhard et al., Llave et al., Parks et al., 2002
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HD-ZIP III transcripts accumulate in PAZ mutants
10ng
30ng
60ng
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miR165 is Expressed Abaxially in Leaf Primordia
miR165
PHB/PHV
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miR165 is Over and Ectopically Expressed in ago1
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AGO1
CAF
22nt miRNA
miRNA precursor
AGO1
AGO1
aaaaaaa
mRNA
aaaaaaa
Adaxialised
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A Model for Leaf Development
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CSHL Plant Group