SHORT-ROOT
SHORT
ROOT and SCARECROW Promote Root Stem
Cell Activityy byy Suppressing
pp
g Stress Signaling
g
g
Hongchang Cui
Department of Biological Science
Science, Florida State University
University,
Tallahassee FL 32306 Email: hcui@bio
Tallahassee,
[email protected]
fsu edu
Observations
Introduction
 U
Unlike
lik animals,
i l plants
l t maintain
i t i ttwo
populations of stem cells after
embryogenesis − one at the shoot tip
tip,
the other at the root tip
p − and
continuous activity of these stem cells
contributes
t ib t to
t th
the iindeterminate
d t
i t
growth of plants
 Stem cell activity is inhibited by stress.
Plants are immotile and
and, to survive an
ever-changing
g g environment,, theyy must
keep a balance between growth and
stress
t
responses
 SCR and SHR are essential for root growth
WT
shr
ABA
(M)
scr
WT
shr
scr
-
+
 shr
h and
d scr mutants
t t are hypersensitive
h
iti to
t
ABA, a stress-associated plant hormone
 The ABA-insensitive aba2 mutant alleviates
the short root defects of shr and scr
40±2
15±2
44±2
 SCARECROW (SCR) and
d SHORTSHORT
ROOT (SHR) are important regulators
of stem cell renewal in root
root, but how
they
h y maintain
i i stem cellll activity
i i y iis
unknown
 We
W ffound
d th
thatt SCR and
d SHR repress
stress response, and the short-root
short root
defects of scr and shr mutants were
alleviated byy mutations in g
genes that
are involved in stress response and
signaling
i
li
34±4
12±2
scr
scr aba2
aba2
R ot le
Roo
eng
gth (m
mm)
R
Results
lt
44±3
scr
scr aba2
aba2
 The scr aba2 and shr aba2 mutants have a
greater number of stem cells
aba2
scr aba2
scr
F t
Future
directions
di ti
 To elucidate the molecular mechanism
b which
by
hi h SCR promotes
t roott stem
t
cellll
activity under stresses
 To identify additional factors that
coordinate
di t roott growth
th and
d stress
t
responses
44±2
aba2
44±3
40±2
shr aba2
34±4
15±2
shr
12±2