physiologia plantarum lectureipnc.ucdavis.edu/powerpoints/r307_0827_1020_briat.pdf · fe + 3...
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Physiologia Plan
Mechanisms of iron hand their r
Dr. Jean‐FraDr. Jean FraCNRS‐INRA Mon
ntarum lecture:
homeostasis in plants pregulations
ancois Briatancois Briatntpellier, France
Jean-François BRIAT
http://www.montpellier.inra.fr/ip p
Mechanisms of iron hand their rand their r
ibip/index.htmp
homeostasis in plants regulations regulations
IPNC Sacramento27 A 200927 August 2009
Iron is an essentia
26 +2Fe +3
Transition metal Fe2
Fe34th element on earthFe 355.85
Fe3
-Low iron availaibility in 1/3 of the cultivate-Diet for 2/3 of the world population is base
Abunda
p pless than 10% of the recommended daily ir
3 billi h b i i d fi i
As a co
3 billion human beings are iron deficientand retardation of mental and psych
Iron entrance in the fIron entrance in the fa major public
http:
al element for life
2+
3+
Ferrous iron, reduced
F i i idis d3+ Ferric iron, oxidised
d soils (calcaraceous)ed on plant food (100 g of cereal flour contain
ant… but
p gon supply)
(i d ibili f i f i
onsequence
t (increased susceptibility for infections homotor development and of growth)
food chain is linked to food chain is linked to health problem//www.who.int/nutrition/topics/ida/en/index.html
Plant Iron Deficiency
Fe3+ Fe2+
H 7
Fe(OH)3 insoluble
pH > 7
3
I b d t i il BUT l il bl f-Iron abundant in soils, BUT poorly available foplants (10-10M soluble/ 10-8M required)
- Iron fertilization expensive and poorly effici- Iron fertilization expensive and poorly effici
- Phenotype of iron deficient plants
Gro
HePhenotype of iron deficient plants
Dec
He
or
ientient
owth decrease and lower yields
avy metals (Zn Mn Cd ) accumulation
creased chlorophyll content
avy metals (Zn, Mn, Cd…) accumulation
Iron Deficiency Alters and Fun
Chloroplasts = plant leaf specific o+ photosynthesis : CO2 ass
and Fun
+ photosynthesis : CO2 assmolecules
+ N and S assimilation ---
These reactions depend upon iron pr(electron transfert chain, nitrite and
+ Fe
Chloroplast Structure nctions
organelles containing chlorophyllsimilation > C skeleton of organic
nctions
similation ---> C skeleton of organic
>Amino Acid and Vitamin synthesis
roteins d sulfite reductases…etc)
- Fe
Iron within the chloroplast
stroma
D2 D1
FLHN
CP47CP43
IJK WMXLhcbiLhcbiLhcbi
PQ
PQ
PQ
IV-cyt b6 GMQA
S E
H+
PC
CP47CP43
OTPR
QRieske
cyt f2 H2O
4H+ + O2
H+LHC
PC
cyt b6fPSIILumen
2 Fe 6 Fe
photosynthetic apparatus
ADP + Pi ATP
II I
FNR
NADP++H+ NADPH
Fd
L
L IKMH G
CE D
JA1 A1’ IIIIII IIIIIIIV
A B
PC 3 H+
NF
LHC
f PSI ATPsynthétasey
14 Fe(from FA Wollman)
Iron is essenti
Fenton Reaction Fe2+ + O Fe3+ + O •-
Fe2+ + H2O2 Fe3+ + HO• + HO-
Fe2 + O2 Fe3 + O2
(Superoxide ion )
(Hydroxyl radical)
Humans :Humans :Hemachromatosis
Plants:Rice « bronzing »
al …but toxic
Oxidative Stress
Molecular principle to coeukaryoy
Uptake : Iron
Storage : FIron excess
U
Iron deficiency
ontrol iron homeostasis in tic cells
n transporters
erritin
Uptake : Iron transporters
Storage : Ferritin
Two different iron uptgraminaceous and non-grai h diff i l iwith a differential sensit
calcarac
N
Picture from V. Rohmeld
take strategies between aminaceous plants correlate i i i il ibili i tivity to iron availaibility in
ceous soils
SOIL ROOTS
H+ HP
FRO2Fe3+
F 2
H+ H+ATPase
2R 1
NON-GRAMINACEOUS
Fe2+ Fe2+IRT1
Phytosiderophores
3
PS PS
GRAMINACEOUS
Fe3+-PSYS1Fe3+-PS
Arabidopsis (non graminaceous
ZIP9
IRT3ZIP6
IRT3ZIP4 ZIP2
ZIP12
ZIP11
ZIP5
ZIP1
Ei ht IRT1ZIP8
IRT2
ZIP3
ZIP5 - Eight pre- WT trans- E103 (red- D100 (blu- D136 (grIRT2
ZIP10ZIP7(g
- H96, H19activity- C109, Y2
(f
s) IRT1 from the ZIP family
di t d t m mb d m i (I VIII)edicted trans-membrane domains (I-VIII)sports Fe, Zn, Cd and Mnd) -->Ala = transports Fe, Cd, Mn but not Znue) -->Ala = transports Zn, Cd but not Fe and Mneen) -->Ala = transports Zn and reduced level of Cd) p97, S198, H224 and E228 (grey) -->Ala = no transport
295, D300 and E305 (yellow) -->Ala = no change with WT
from Rogers et al �[2000] PNAS 97 : 12356-12360)
Localisation of IRT1
pIRT1::GUS fusions expressed at the rooperiphery in the epidermal cell layer in re
+ Fe - Fe
periphery in the epidermal cell layer in reto iron deficiency
IRT1 RNA d t t d i th t IRT1 mRNA detected in the root periphery by in situ hybridization
expression territories
C Dp35S::GFP
C D
ot esponse
p35S:: IRT1-GFPesponse
B
IRT1-GFP fusion localized IRT1-GFP fusion localized at the plasma membrane
IRT1 is involved
WT irt1-1
R LRL+ - + + +- - -Fe :
121.368.840 040.028.4
16.8
WT iIRT1-KO mutant is chlorotic and altin its development.
Vert et al (2002) The Plant Cell 14 : 1223-1233
d in iron uptake
30DW
10
20
e 55
Fe/m
g D
1 1
0
10
pmol
e
+Fe -Fe +Fe -Feirt 1-1 tered
WT Irt1-/-
55Fe feeding for 48 hours i di h i 1 / i indicates that irt1 - / - is deficient in iron uptake
ConcluConclu
IRT1 is the Major Transporter in Dicots to
ConcluConclu
Transporter in Dicots toSoil in case o
Vert et al (2002) The P( )Varotto et al (2002)
Henriques et al (2002) Pl
IRT2 shares the same but its function is nobut its function is noVert et al (2001) The
Vert et al (2009) PlVert et al (2009) Pl
usionusion
Essential Root Iron o Take Up Iron from the
usionusion
o Take Up Iron from the of Deficiency
Plant Cell 14 : 1223-1233 Plant J 31 : 589-599ant Mol Biol 50 :587-597
territories than IRT1, ot redundant to IRT1ot redundant to IRT1e Plant J, 26 : 181-189lanta 229:1171-1179 lanta 229 1171 1179
Maize (grami
WT
YS1 f
ys1
YS1 f
Interv
DeficiDeficiuptake106 :
Ac transposon tagging of ys1 byMassachussets at Ahmerst)
2.8 kb ys1 cDNA cloned from ostarved plants
naceous) YS1
WT
ys1
for Yellow Stripe 1 (Beadle, 1929)for Yellow Stripe 1 (Beadle, 1929)
veinal leaf yellowing
ient in Fe(III)-mugineic acid root ient in Fe(III)-mugineic acid root e (von Wiren et al., 1994, Plant Physiol 71-77)
y Elsbeth Walker (University of
our root library originated from iron-
Maize YS1 and 8 YS-are ver
NHER GLE
Arabidopsis YSL are highly conserved
NH2E
Arabidopsis YSL are highly conservedmaize YS1 :
- 70 to 80 % similarities- 12 putative transmembrane do12 putative transmembrane do- E residues enrichment at the
terminal extremity- REGLE-like motif conservation
NH2-terminal extremity - both belongs to the Oligo Pept
Transporter (OPT) family
-Like from Arabidopsisry similar
COOH
d with
COOH
d with
omains YSL1
ZmYS1YSL2 YSL3
omainsNH2-
n at the YSL6YSL8
YSL4
tide
YSL6
YSL7YSL5
Curie et al (2001) Nature 409 : 346-349
ConcluConclu-YS1 is the major graminaceous Fuptake transporter
YS1 i l bl t t t F-YS1 is also able to transport Feheterologous systems (yeast ans
EightArabidopsis thaliana genes- EightArabidopsis thaliana genesmaize Ys1, raising the questions plants, and of the nature of the (Iron-Nicotianamine?)(Iron Nicotianamine?)
Curie et al (20
Electrophysiology of YS1 = protosymporter
Schaff et al (2004
usionsusionsFe(III)-phytosiderophores
(II) NA h d i e(II)-NA when expressed in Xenopus oocytes)
s (ysl 1 8) are homologous to s (ysl 1-8) are homologous to of their role in non graminaceous substrate they could transport
001) Nature 409 : 346-349
on coupled phytosiderophore
4) J Biol Chem 279 : 9091-9096
bHLH trancription regulation of iron upt
factor networks for take transport systems
Colangelo and Guerinot (2004) Plant Cell 16: 3400-3412
Jakoby et al. (2004) FEBS Lett 577 : 528-534
Yuan et al (2005) Cell Research 15 : 613-621
O t l (2007) Pl t J l 51 Ogo et al (2007) Plant Journal 51: 366-377
Ogo et al (2008) J Biol Chem. 283 Ogo t a ( ) J o h m. : 13407-13417.
Kobayashi et al (2007) PNAS 104: 19150 19155
From Lemanceau et al (2009) Plant Soil 321: 513-535
19150-19155
Iron circulation withinth l tthe plant
Fe(III)-citrate and Fe(II) NA are two major chelates for iron distribution throughout the plant via xylem (blue) and phloem (pink) saps
Frd3 (MATE type) involved in citrate loading of xylem
YS1IRT1
Fe(II)-NA is transported by YSLs
IRT1Nicotianamine (NA)
structure
YSL transportersBriat et al (2007) Curr Op Plant Biol 10 : 276-282Curie et al (2009) Ann Bot 103 : 1-11
Overview of sub-cellular
Vacuole iron influxer (VIT1) and effluxerVacuole iron influxer (VIT1) and effluxer(Naramp3 / Nramp4) have been identifi
Tranporters for mitochondria and Chloroplasts iron uptake are still uncharacterized
Both mitochondria and chloroplastsare able to synthesize heme and Fe-Sl
B i t t l (2007) C O Pl t Bi l 10 276
clusters
Briat et al (2007) Curr Op Plant Biol 10 : 276-
iron utilisation in plant cells
YSL4rs YSL4YSL6 ?
rsed
282-282
Arabidopsis thaliana ferri
. Ferritins are located in plastids
. 4 genes in Arabidopsis AtFer1 to -4Gaymard et al., 1996 Biochem. J. Petit et al., 2001 Biochem. J. 359
AtFer1
shoots0h 3h 6h 12h+ Iron
AtFer1AtFer2AtFer3AtFer4
AtFeregu
AtFer1 = most expres
AtFer425 S
response to iron excess homeostasis r
tins
318, 67-739, 575-582
Fer1, -3 and -4 transcriptional ulation in response to iron excess
ssed ferritin gene in model to study iron
regulation
WORKING MODEL Arnaud etBriat et al
IDT
REPRA- Low iron
B- High iron
ID
AtFer1 promoter5’
FeB H gh ron
PlastidNOS activity
enzymeym
NO
7mproteasome d d t
PPdependent
degradation REPRESSOR
Ub
IDRS
AtFer1 promoter5’
UbTF
t al (2006) J Biol Chem 281 : 23579-23588(2009) Ann Bot (in press)
AtFer1DRSTF
ESSOR
AtFer1DRS 3’
mGpppGAUG
PolyAAtFer1 mRNA
P2A
AtFer1 3’
Ferritin gene exArabidopp
A bid i AtF 2 d iArabidopsis AtFer2 expressed speci
Arabidopsis AtFer1-3-4 expresseroots floral stalk) in flowers anroots, floral stalk), in flowers, an
pression in various opsis organsp g
ifi ll i t difically in mature seeds
ed in vegetative organs (leaves, nd in germinating seeds
Petit et al., 2001 Biochem. J. 359, 575-582
nd in germinating seeds.
What do we learn cfunction in planta usifunction in planta, usi
approach in A
Ravet et al., 2009 Pla
- Ferritin function in seeds- Ferritin function in leaves- Lack of ferritins and flowe- Role of ferritins in iron me
concerning ferritin ing a reverse genetic ing a reverse genetic Arabidopsis ?
ant. J. 57 : 400-412
er developmentediated oxidative stress
What do we learn cfunction in planta usifunction in planta, usi
approach in A
Ravet et al., 2009 Pla
- Ferritin function in seeds- Ferritin function in leaves- Lack of ferritins and flowe- Role of ferritins in iron me
concerning ferritin ing a reverse genetic ing a reverse genetic Arabidopsis ?
ant. J. 57 : 400-412
er developmentediated oxidative stress
T-DNA insertiAtFer2 F
fer2
Seed Col fer2
LB LBT-DNA
Seed Ferritins
Coomassie
T-DNA insertion in the AtFer2 gene l d t m t t d l ki f itileads to mutant seeds lacking ferritin
Iron content is unchanged in ferritin
Seed ferritins are not a ma(Iron ferritin = 5%
on mutant in the Ferritin Gene
Col fer20 12 24
Time (h) after seed imbibition 0 12 240 12 24
Ferritins
Coomassie
after seed imbibition 0 12 24
7575
Fe c
onte
ntµg
.g-1
DW
)
25
50
0
25
50
75
F (µ
0
1 2
0
Col fer2 ns
nless fer2 seeds
ajor iron store in Arabidopsis% of total seed iron)
Role of Fer2 seed against oxg
80
100
on(%
)
40
60
erm
inat
i
Colf 2
0
20
0 2 4 6 8 10
G fer2fer2 x 35S::AtFer1
0 2 4 6 8 10
Methylviologene (µM)
S d f i i i i Seed ferritins participate to prduring the ger
ferritin in protectionxidative stress
Germination of Germination of ferritinless fer2 seeds is more sensitive to methylviologen treatment
12
methylviologen treatment than wild type Col seeds
12
i i id i rotection against oxidative stressrmination process
Iron storage subcellular
VofofS
Nfovaet
Sst20
Hobetest
compartmentation in seeds
VIT1 is necessary for iron loading f vacuoles in seeds (Kim et al 2006 f vacuoles in seeds (Kim et al 2006 cience 314:1295-1298)
NRAMP3and NRAMP4 are required or Fe remobilization from acuoles during germination (Lanquar t al 2005 EMBO J 24 :4041-4051
Seed ferritin FER2 not a major torage form in plastids (Ravet et al, g p009 Plant. J. 57:400-412)
owever, is there any crosstalk tween vacuoles and plastids to tablish seed iron homesotasis?
Vacuoles / Plastids croIron Ho
2 2
Iron Hom
p3-4
#2
mp3
-4#
1
:NRa
mp3
#1
:NRa
mp3
#2
:NRa
mp4
#1
:NRa
mp4
#2
Col
nram
WS
nram
35S:
35S:
35S:
35S:FERRITI
Coomassblue stain
Seed ferritin Fer2 pronramp3nramp4 KO mut
(Ra
osstalk to establish Seedomeostasisomeostasis
:Vit
1#10
:vit
1#17
Col
vit1
35S:
:
35S:
:
NS
siening
otein abundance decreased in tants and in VIT1 overexpressors
avet et al, 2009 Molecular Plant, in press)
Vacuoles / Plastids croIron HoIron Ho
2,5
1,5
2
RNA
leve
lL) N
A le
vel
0,5
1
AtFe
r2m
R(R
TL
tFer
2m
RN
0
A
1 2 3 4 5 6 7 8 9
Col nramp3-4#21 2 3 4 5 6 7 8 9
At
Seed ferritin Fer2 tranramp3nramp4 KO mut
Post-transcriptional regulation of
(Ra
Post-transcriptional regulation ofa functional iron storag
osstalk to establish Seedomeostasis omeostasis
NA
leve
lL)
10000
150003
2 10000
150003
2
tFer
2m
RN(R
TL
0
50001
0 0
50001
0
AtWS nramp3-4
#1
0
1 2
0
Col nramp3-4#2
0
1 2
0
anscript abundance unaffected tants
f ferritin AtFer2 in seeds requires
avet et al, 2009 Molecular Plant, in press)
f ferritin AtFer2 in seeds requiresge vacuolar compartment
What do we learn cfunction in planta usifunction in planta, usi
approach in A
Ravet et al., 2009 Pla
- Ferritin function in seeds- Ferritin function in leaves- Lack of ferritins and flowe- Role of ferritins in iron me
concerning ferritin ing a reverse genetic ing a reverse genetic Arabidopsis ?
ant. J. 57 : 400-412
er developmentediated oxidative stress
T-DNA insertiAtFer1-3 and
fer1
fer4 T-DN
AtF 4Col
LB RBT-DNA fer4
genesand f
T DNAtFer4
EF1�
T-DNAtFermutan
Obtention of the triple fercrossing using single fer1,
on mutant in the -4 Ferritin Genes
fer3
AtFer3
Col fer3- + - + FeLB
T-DNA
EF1�
NA insertion in AtFer1 and AtFer4s leads to knock-out null single fer1fer4 mutants
NA insertion in promoter region of NA insertion in promoter region of er3 leads to knock-down single fer3nt
er1-3-4 mutants by succesive fer3 and fer4 mutants give
Ferritin protein subuvarious fevarious fe
2
- +
Col
- +
fer
2
+ +
28kDa26.5kDa
Confirmation that Fer2 protein is
Fer1 is the major ferritin proteisubunit whereas Fer3/4 are subusubunit, whereas Fer3/4 are subu
No ferritin subunits are detected
unit content in leaves oferritin mutantserritin mutants
3-4
+ - + - +
fer
1
fer
1-3
Fe
Ferritins
+ + + Fe
Coomassie
absent in leaves
in in leaves present as a 28 kDa units of 26 5 kDaunits of 26.5 kDa
in leaves of the fer1-3-4 triple mutant
Arabidopsis rosette biomassand in the fer1-3-4 triple m
C l fer1 3 4F
and in the fer1 3 4 triple m
-
Col fer1-3-4Fe
(
+
D M
ttNo biomass difference between Col (No biomass difference between Col (mutant devoided of leaf ferritin whe
Irrigating Col with a Fe-EDDHA solu
Irrigating fer1-3-4 with a Fe-EDDH
s in wild type Arabidopsismutant lacking leaf ferritinsmutant lacking leaf ferritins
er(m
g.
-1)
400
600
800
fer1-3-4/H2O
800
600
400
Col/FeCol/H2O
35S::AtFer1-fer1-3-4 /Fe
Dry
Mat
tepl
ant-
0
200
400
20 25 30 35 40 45 5020 30 40 50
400
200
0
fer1-3-4/Fe
Time after sowing(days)
(wild type plants) and the fer1-3-4
20 30 40 50
(wild type plants) and the fer1 3 4en irrigated with tap water
ution increases its biomass
HA solution decreases its biomass
Analysis of variouthe fer1 3 4 mutant phthe fer1-3-4 mutant phCol fer1-3-4
F ein
PsaD
- + Fe- +
300
400
500
hyll
/ pr
ote
300
400
500
PsbA
b6f
100
200
300
io C
hlor
oph
100
200
300
PsbA
Fdx
0Rati
0
NFU2 Amounand phhlCoomassie chloro
fer1-3
us components of hotosynthetic apparatushotosynthetic apparatus
Col
0
0
0
Colfer1-3-4
0
0
0
1 2 3 4 5 6 7- +Fe
nts of plastidial electron transfert chain hotosynthesis related polypeptides, and h ll h d i h phyll content are unchanged in the
3-4 mutant.
Photosynthesis activity
0,8
0,6
SII
0,2
0,4
0 200 400 600 800 1000
PS
0 200 400 600 800 1000PAR(µE.m-2.s-1)
Quantum yield of PSII (PSII) is ufer1-3-4 mutant under Fe or water
N Ph h d dNet Photosynthesis rate is decreade4 mutant when irrigated with 2 mM
in the fer1-3-4 mutant
20
esis
)
10
15
hoto
synt
hCO
2.m-2
.s-1
0
5
0 200 400 600 800 1000Rate
of
Ph(µ
mol
C
0 200 400 600 800 1000R
PAR(µE.m-2.s-1)
Col / H2OCol / H2Ofer1-3-4 / H2OCol / Fefer1-3-4 / Fe
unaffected in the r irrigation
d h f 1 3ed in the fer1-3-Fe-EDDHA
What do we learn cfunction in planta usifunction in planta, usi
approach in A
Ravet et al., 2009 Pla
- Ferritin function in seeds- Ferritin function in leaves- Lack of ferritins and flowe- Role of ferritins in iron me
concerning ferritin ing a reverse genetic ing a reverse genetic Arabidopsis ?
ant. J. 57 : 400-412
er developmentediated oxidative stress
Pleiotropic alterationsin the fer1
Col fer1-3-4
f
1000
g.pl
ant-
1 )500
750
d yi
eld(
mg
0
250Se
ed
Impaired flower and silique developm
Seed production decreases in the fe
p q p
during fruit formation -3-4 mutant m
Col fer1-3-435S::AtFer1 fer1-3-4
## #
*
*
#1
#4
#10
0 0 5 1 2
*
0 0.5 1 2 Fe (mM)
ment in Fe-irrigated fer1-3-4 mutant
fer1-3-4 mutant irrigated with iron
g
Reciprocal graftinfer1-3-4 bf
fer1-3-4Col fe
ng between Col and bolted plants p
fer1-3-4 flowers phenotype is
Coler1-3-4
ph notyp s independent of leaves.
Iron content in Col and
400 1000Colfer1-3-4
e co
nten
tµg
.g-1
DW
)
200
*
500
1000
Fe (µ
0 0+
stem
+-
Under water irrigation conditions F
Under iron irrigation conditions Fe
Under water irrigation conditions, Ffer1-3-4 plants in floral stem, and
Under iron irrigation conditions, Fe fer1-3-4, and increases in unfertilito Col
d fer1-3-4 floral stalks
Colfer1-3-4 *
*
++
unfertilizedflower
fertilizedflower
++- -
e content is unchanged between Col and
content decreases in floral stems of
e content is unchanged between Col and in unfertilized or fertilized flowers
content decreases in floral stems of zed or fertilized flowers, comparatively
Metal transporters expres
Fold change of the expression of varmetal transporter genes betweenmetal transporter genes betweeniron irrigated or water irrigated planare altered in fer1-3-4 comparative
Alteration of iron allocation betflowers in fer1-3-4 plants coul
of expression of various
ssion in Col and fer1-3-4
Gene AGI Col fer1-3-4 Col fer1-3-4NRamp1 At1g80830 -3,7 -1,5 -1,6 2,2NRamp2 At1g47240 -2,1 -2,5 -1,1 1,0NRamp3 At2g23150 20 2,0 4,4 -1,2NRamp4 At5g67330 1 5 -1 5 2 2 2 1
Stem Flowers
NRamp4 At5g67330 1,5 -1,5 2,2 2,1NRamp5 At4g18790 43 30 9,6 2,7NRamp6 At1g15960 2,0 6,0 37 6,2
YSL1 At4g24120 2,4 1,3 1,3 -2,3YSL2 At5g24380 -2,2 -4,9 -130 -281YSL3 At5g53550 1,6 8,9 3,9 4,0YSL4 At5g41000 7,5 1,8 2,7 -6,6YSL5 At3g17650 1 3 2 1 1 1 4 0
riousYSL5 At3g17650 -1,3 2,1 1,1 4,0YSL6 At3g27020 1,2 -1,2 1,5 1,2YSL7 At1g65730 8,1 1,1 2,7 -6,0YSL8 At1g48370 -1,3 -2,2 -1,7 -2,9IRT1 At4g19690 1,4 -40 2,1 -468IRT2 At4g19680 1,2 -104 1,5 -9,4ZIP1 At3g12750 -1,4 -2,0 1,9 1,3ZIP4 At1 10970 1 3 3 1 1 2 1 8
ntsely to Col
ZIP4 At1g10970 1,3 3,1 1,2 1,8ZIP5 At1g05300 13 3,6 -2,5 -1,4ZIP6 At2g30080 -1,4 -1,6 -2,2 -1,9ZIP9 At4g33020 7,6 6,9 2,0 1,3ZIP12 At5g62160 7,2 18 1,7 -2,1Pic1 At2g15290 1,6 1,8 6,7 14Vit1 At2g01770 -1,5 1,4 1,1 1,0
Induction � 20 20 > Repression � 2
20 > Induction � 2 Repression � 20
tween stems of floral stalks and ld be related to the deregulations metal transporter genes
What do we learn cfunction in planta usifunction in planta, usi
approach in A
Ravet et al., 2009 Pla
- Ferritin function in seeds- Ferritin function in leaves- Lack of ferritins and flowe- Role of ferritins in iron me
concerning ferritin ing a reverse genetic ing a reverse genetic Arabidopsis ?
ant. J. 57 : 400-412
er developmentediated oxidative stress
ROS imaging in Arabid pArabidop
GUS stainingRO i
Col fer1-3-4 Col fer1
gCol Fe
pAtFer1:GUS
- +ROS im
pAtFer3:GUS
pAtFer4:GUS
DCFDA ROSi i
Chlorop
GUS
imaging
Reactive Oxygen Species (3 4 flowers from water ir3-4 flowers from water irfrom iron irrigated plants,
Col and fer1-3-4psis fl ers psis flowers
i
r1-3-4 Col fer1-3-4
aging
ROS qu ntific ti n
200
200
(a.u
.) *Colfer1-3-4
quantification
hyll Overlay50
100
150
100
0ores
cenc
e
069
0
Flu
(ROS) overaccumulate in fer1-rrigated plants (and even more rrigated plants (and even more , not shown)
ROS detoxyfying enzyand fer1 3 4 Arabid pand fer1-3-4 Arabidop
A
y min
-1)
60*
Catalase
C lfer1-3-4
1500y min
-1)
pe
AT
acti
vity
.g-1pr
otei
n.
20
40 *
Col
1000
1500
PX a
ctiv
ity
.g-1pr
otei
n.
CA(µ
mol
e.
0
20
1 2 3 4 5leaf flower 0
500
1
AP
(µm
ole.
le
ROS detoxyfying enzyme fer1-3-4 leaves and flowe(and even more from iron
yme activities in Col psis leaves and fl ers opsis leaves and flowers
Glutathioned
Ascorbateid
min
-1)
reductaseeroxidase
*l
fer1-3-490
*fer1-3-4
R ac
tivi
ty-1pr
otei
n.m
*
Col
60
90
*
Col
GR(µ
mol
e.g-
2 3 4 5eaf flower 0
30
1 2 3 4 5leaf flower
activities are enhanced in ers from water irrigated plants g pirrigated plants, not shown)
Conclus
Fer2 is the only seed ferritin- limited function in iro- role for protecting grole for protecting g
oxidative stress
A f 1 3 4 t t h lA fer1-3-4 mutant has no le- its biomass is affect- its CO2 fixation is de
the thylakoid electron transf
fer1 3 4 mutant has pleiotrofer1-3-4 mutant has pleiotroirrigated with iron
- independently of the l d d ld - leading to seed yield
ions (I)
n in Arabidopsis with a :on storageerminating seedlings against erminating seedlings against
f f iti d tleaf ferritin and consequentlyed when irrigated with ironecreased, without alteration of fer chain
opic flower defects when opic flower defects when
lack of ferritins in leaves d decrease
Conclusi
Expression of various metal tfer1-3-4, consistent with anbetween stems of floral stalk
ROS scavenging mechanisms a- sufficient to avoid ox
irrigationirrigation- unsufficient under Fe
(decreased biomass, flower athese conditionsthese conditions
ons (II)
transporters is deregulated in n alteration of iron allocation k and flowers
are enhanced in fer1-3-4 plantsxidative damages under water
e excess, explaining phenotypes and siliques alterations) under
Iron nutrition and homeostasis is aIron nutrition and homeostasis is a
many molecular actors which are in
through complex regulatory pathwa
signaling, transcription factor netw
controls etc) controls …etc) ………………..
…. It is another story w
Than you foy u f
a very dynamic process involvinga very dynamic process involving
ntegrated at the whole plant level
ays (hormones, long distance
works, post-transcriptonal
which is starting to emerge ….
or your attention ! y u