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