altering light perception during tomato fruit ripening significantly affects antioxidant...
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Altering light perception during tomato fruit ripening significantly affects antioxidant accumulation
LW+UV
LW HW
D FR R B
Chloroplasts “compartment size”: organelle population signalling, and the uncovering of chloroplast “master
switches”.
A tomato mutant with enhanced antioxidants (hp2) - shows enhanced plastid development, and - is defective in a repressors of photomorphogenesis (LsDET1)
hp2j
WT
A cell’s plastid complement is dramatically affected by loss of LsDET1
hp2j
WT
Absolute plastid area, inner mesocarp
0
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50000
0 100000 200000 300000
Cell area
Pla
stid
are
a
hp2
WT
Absolute plastid area, outer mesocarp
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0 100000 200000Cell area
Pla
stid
are
a
WT
hp2
Loss of LsDET1 leads to at least a doubling in plastid complement
Relative plastid compartment
8.35
25.52
0
5
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15
20
25
30
WT Com hp2j ComGenotype
Pla
stid
co
mp
art
me
nt (
%)
Fruit-specific silencing of LsDET1 also leads to increased cellular plastid compartment
wild type2A11p:DET1
i
TFM7p:DET1iP119p:DET1
i
0
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T56 2A11 TFM7 P119
Pla
stom
e/n
ucl
ear
genom
e r
ati
o
(Unpublished data by E. Enfissi)
(Plants of Davuluri et al. 2005,
Nature Biotech. 7: 890-895)
The increase can also be measured as plastome/genome ratio
Importantly, increased plastid compartment can be achieved by combinations of increases in plastid size and number
0
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0 20000 40000 60000
Num
ber
of
plas
tids
per
cell
Tot
al p
last
id a
rea
per
cell
(μm
2)
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9000
0 20000 40000 60000
TFM7T56 (WT)TFM7T56 (WT)
Ave
rage
pla
stid
siz
e (μ
m2)
0
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T56 TFM7
Ave
rage
pla
stid
siz
e (μ
m2)
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T56 TFM7
Exoca
rp
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0 40000 80000 120000
0
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9000
0 40000 80000 120000
Num
ber
of
pla
stid
s p
er
cell
Avera
ge p
last
id s
ize (
μm
2)
Tota
l p
last
id a
rea p
er
cell
(μm
2)
0
2
4
6
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10
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14
16
T56 TFM7
0
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0 40000 80000 120000 160000
0
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0 40000 80000 120000 160000
Cell area (μm2) Cell area (μm2)
Num
ber
of
pla
stid
s p
er
cell
Avera
ge p
last
id s
ize
(μm
2)
Tota
l p
last
id a
rea p
er
cell
(μm
2)
Genotype
0
2
4
6
8
10
12
14
16
T56 TFM7
Oute
r meso
carp
Inner m
eso
carp
Plastid “growth” matters
Tight control of the total cellular plastid complement has long been known in cereal leaves
Since plastid growth results from the expression of nuclear genes, this implies “plastid compartment size” retrograde signalling
(Ellis and Leech 1985,Planta 165: 120-125)
(Pyke and Leech 1987,Planta 170: 416-420)
3dD +1dL +2dL
+3dL+4dL +5dL
Chloroplast biogenesis can be followed as part of a whole transcriptome analysis of leaf initiation in the light (distinguishing the shoot apex and the cotyledons)
Plastid division
0.0
0.5
1.0
1.5
2.0
Mer
0
Mer
1
Mer
2
Mer
6
Mer
24
Mer
48
Mer
72
Cot
0
Cot
1
Cot
6
Rel
ativ
e ex
pre
ssio
n
ARC5
FtsZ
Indeed light upregulates specifically in the shoot apex components of the plastid division process, but this is unlikely to be the driving force in chloroplast accumulation. Many other
processes occur.
Combined examination of biochemically-unrelated chloroplast biogenesis genes reveals the existence of “modules” of
corregulated genes.
TIC 110