aba increases [ca 2+ ] cyto influx through plasma membrane or release from internal compartments
Post on 14-Jan-2016
24 Views
Preview:
DESCRIPTION
TRANSCRIPT
ABA increases [Ca2+]cyto
influx through plasma membrane or release from internal compartments
Verapamil: an inhibitor of extracellular Ca2+ channels
TMB-8: an an inhibitor of intracellular Ca2+ channels
J. Exp. Bot. (1995) 46: 973-979
Microinjected Ca2+(cyto) sensitive dye- fura-2
Non-invasive method:
transgenetic plants expressing the gene for the calcium indicator protein
yellow cameleon
ABA-induced calcium oscillation in guard cells of Arabidopsis
Web Topic 23.9A Ca2+ binding fusion protein: Ca2+ indicator yellow cameleon
Composed 4 domains: enhanced cyan fluorescence protein (ECFP)
enhanced yellow fluorescence protein (EYFP)
calmodulin (CaM)
CaM-binding protein (M13)
The 535/480 emission ratio [Ca2+]cyto
* p. 606
Reactive oxygen species (ROS), inositol 1,4,5-triphosphate (IP3),
cyclic ADP-ribose (cADPR), self-amplifying
activate channel
* ABA nitric oxide cADPR stomatal closure
* p. 607R
Auxin-induced stomatal opening [Ca2+]cyto
the location and periodicity of calcium oscillations rather than the
overall concentration of cytosolic calcium, determine the cellular response.
Phalaenopsis: citric acid/ malate
¤ ABA inhibits the plasma membrane H+-ATPase
also contribute membrane depolarization indirectly
ABA inhibition proton pump is via increase [ca2+]cyto and alkalizatio
n of the cytosol (pH 7.677.94, p. 607R)
p. 452
¤ p. 603
ABA activate slow and rapid (06) anion channels in guard cells
large amounts of Cl- and malate2- to escape from the cell
depolarization (more positive) / calcium factor
open voltage-gated K+ efflux channels
( long-term membrane depolarization)
Anion channel inhibitors:
5-nitro-2,3-phenylpropylaminobenzoid (NPPB) – slow type
block ABA-induced stomatal closing
4,4’-diisothiocyanatostilbene-2,2’-disulfonic acid (DIDS) – rapid type
have no (02) effect on ABA-induced stomatal closing
¤ ABA prevents light-induced stomatal opening
– inhibit the inward K+ channel
¤ stomatal closing of guard cells under stress
prevent opening:
inhibit inward K+ channels and plasma membrane H+ pumps
promote closing:
activate outward anion channels, then active K+ efflux channels
ABA signaling involves both Ca2+ dep- and independent pathway
“network robustness”
Daily changes in stomatal aperture, and in sucrose and K+ content
Red light: only sucrose accumulation
Stomatal opening is associated primarily with K+ uptake, and
closing is associated with a decrease in sucrose content, why?
Plant cell (04) 16: 1143-1162 The ascorbic acid redox state controls guard cell signaling and stomatal movement
top related