GIGANTEA mediated salt stress GIGANTEA-mediated salt stress signaling in plant g g p
(식물에서 자이겐티아에 의한 내염성 기작 조절)
Woe Yeon Kim
World Class University Program and Department of Applied life chemistry Department of Applied life chemistry,
Gyeongsang National University
GIGANTEA (GI)GIInput
- photomorphogenesis
GIGANTEA (GI)
OscillatorLHY TOC1
photomorphogenesis, - photoperiodic flowering regulation- circadian clock regulation
OscillatorLHYCCA1
TOC1g
- excess starch accumulation- alterations to sucrose metabolism
lt d iti it t GI
- altered sensitivity to Light, Cold, and Oxidative stress
CO
Output(photoperiodicfl in C d f 1173
FTflowering pathway)
~ Composed of 1173 a.a.
GIGANTEA controls the circadian clock and time of flowering through protein stabilizationtime of flowering through protein stabilization
Modified from Deng (2012) Trends in Plant Science
Salt stress inhibits plant growth and delays p g yflowering time in Arabidopsis plants.
Xua Li et al. (2007) Plant Growth Regul.
Floral transition in Arabidopsis
GI
TOC1
ZTL GI FKF1
CDF1
CO
LFY
Modified from Blázquez et al. (2001) EMBO reports
CO plays a key role in salt-induced late floweringp y y f g
Xua Li et al. (2007) Plant Growth Regul.
Does GI play a role in salt induced late flowering ?
300 mM25 mM
20
g tim
em
ber)
25 mM
10
Flow
erin
g(le
af n
um
WT GI-OXgi-1 WT GI-OXgi-10 WT GI-OXgi-1
GI is degraded upon salt stress
Transcript 0 12 24 (hr)
Protein 0 12 24 (hr)
3 ControlNaClMG132NaCl+MG132n
(fold
)
( )GITUBGI-HA
( )Control
NaCl2
NaCl+MG132
GI p
rote
in
MG132NaCl+MG132
0
1
Rel
ativ
e G
00 12 24
Time (hr)
R
GI mutant exhibits increased salt tolerance
WT GI-OX gi-1
0 mM
A
ed
B
4
5150mM NaCl
ht (g
)
0 mM
plan
ts T
reat
ew
o w
eeks
2
3
resh
wei
g150 mM
250 Mw
eeks
old
pith
sal
t for
tw0
1Fr
WT GI-OX gi-1
250 mMTh
ree w
Salt stress tolerance in Plants
[Ca 2+]ext
High [Na +]
SOS1
H +Sodium efflux
[Ca 2+]int
PM
Ion SOS3 SOS2
SOS1
Na +
Na +
[ ]int
homeostasisSalt stress signaling
H + H +
Ca 2+
V-ATPasePPase
MYC/MYB/AREB/DREB2A
NU
Compartmentation
NHX
VacuoleH +
N + 2
RD22, ADH, RD29a/bP5CS,BADH
Na +
Na +
ABI2
Ca 2+
SOS3SOS2
Osmolytes(Proline, betaine)?
K +
HKT1Na
Receptor
Modified from Cheong and Yun (2007) J. Plant Biol
betaine)
Does GI regulate general stress pathway ?
Salt stress tolerance in Plants
[Ca 2+]ext
High [Na +]
SOS1
H +Sodium efflux
[Ca 2+]int
PM
Ion SOS3 SOS2
SOS1
Na +
Na +
[ ]int
homeostasisSalt stress signaling
H + H +
Ca 2+
V-ATPasePPase
MYC/MYB/AREB/DREB2A
NU
Compartmentation
NHX
VacuoleH +
N + 2
RD22, ADH, RD29a/bP5CS,BADH
Na +
Na +
ABI2
Ca 2+
SOS3SOS2
Osmolytes(Proline, betaine)?
K +
HKT1Na
Receptor
Modified from Cheong and Yun (2007) J. Plant Biol
betaine)
SOS1 i l b N /H hSOS1 is a plasma membrane Na+/H+ exchanger
GI mutant plasma membrane vesicles exhibits high Na+/H+ antiporter activityNa /H antiporter activity
20gi-1
15
n-1
mg-
1 gi-1Col-0sos1-1
+NaCl
5
10
/Fm
axm
i
0
5∆F/
0 50 100 150 200 250NaCl (mM)
GI influences SOS1 stability
SOS1WB:
SOS1 Anti-SOS1
CBBCBB
SOS1Transcript
TUB
p
GI mutants exhibits increased salt tolerance
ore
ter
Bef
o
mM
Aft
150
mM
0
1
GIGANTEA controls the circadian clock and time of flowering through protein stabilizationtime of flowering through protein stabilization
Modified from Deng (2012) Trends in Plant Science
Sites for GI to regulate salt stress ?
Hi h [N +]High [Na +]
SOS1
Na +
H +
GI?Ca 2+ SOS3
SOS2GI?GI?
GI?
GI interaction with SOSs proteins
DIC YFP MERGE
GI-VN +VC-SOS2
GI-VN +VC-SOS2
GI-VN +VC
VN +VC SOS2
C I i it ti
VC-SOS2
Bimolecular FluorescenceCo-Immunoprecipitation assay Bimolecular Fluorescence Complementation (BiFC)
GI interacts SOS2 directly in vitro
Input S2 S3
35S- GISOS1
H +
GST
35S-
GI
Input
GST
-SO
S
GST
-SO
S
SOS3SOS2
GI?GI?Na +
35S- GI High [Na +]
Ca 2+
CBB
GST- SOS2
GST- SOS3H +
GSTSOS3
SOS1
Na +
High [N +]
Ca 2+SOS2
GI[Na +]
SOS1 is phosphorylated by SOS2 upon salt stress
SOS1:His
Quintero et al. (2002) PNAS 99: 9061-9066
GI inhibits SOS2 kinase activity
12)
68
1012
sity
(SO
S1)
246
ativ
e in
tens
0Rel
a
gi-1 salt tolerance and SOS1 stability is SOS2 dependentdependent
ore
Bef
oM
Afte
r m
M
0 m
M15
0 m
Sites for GI to regulate salt stress ?
Hi h [N +]High [Na +]
SOS1
Na +
H +
GI?Ca 2+ SOS3
SOS2
GI?
SOS2
GI
GI/SOS2 interaction is abolished by SOS3 and Salt
Hi h [N +]High [Na +]SOS1
SOS3
GISOS2SOS2
GI SOS3
100 mM NaCl / 24 h-NaCl
Working Model
High [Na +]
- SALT +SALTSalt tolerance g [ ]
SOS1
Na +
H +
SOS1 P
Ca 2+
SOS3 SOS2SOS3
GISOS3
SOS2
Inhibition
SOS2SOS3
GI GI