TY  - JOUR
A1  - Huang, Shouguang
A1  - Waadt, Rainer
A1  - Nuhkat, Maris
A1  - Kollist, Hannes
A1  - Hedrich, Rainer
A1  - Roelfsema, M. Rob G.
T1  - Calcium signals in guard cells enhance the efficiency by which abscisic acid triggers stomatal closure
JF  - New Phytologist
N2  - During drought, abscisic acid (ABA) induces closure of stomata via a signaling pathway that involves the calcium (Ca2+)-independent protein kinase OST1, as well as Ca2+-dependent protein kinases. However, the interconnection between OST1 and Ca2+ signaling in ABA-induced stomatal closure has not been fully resolved.

ABA-induced Ca2+ signals were monitored in intact Arabidopsis leaves, which express the ratiometric Ca2+ reporter R-GECO1-mTurquoise and the Ca2+-dependent activation of S-type anion channels was recorded with intracellular double-barreled microelectrodes.

ABA triggered Ca2+ signals that occurred during the initiation period, as well as in the acceleration phase of stomatal closure. However, a subset of stomata closed in the absence of Ca2+ signals. On average, stomata closed faster if Ca2+ signals were elicited during the ABA response. Loss of OST1 prevented ABA-induced stomatal closure and repressed Ca2+ signals, whereas elevation of the cytosolic Ca2+ concentration caused a rapid activation of SLAC1 and SLAH3 anion channels.

Our data show that the majority of Ca2+ signals are evoked during the acceleration phase of stomatal closure, which is initiated by OST1. These Ca2+ signals are likely to activate Ca2+-dependent protein kinases, which enhance the activity of S-type anion channels and boost stomatal closure.
KW  - abscisic acid (ABA)
KW  - Ca2+- indicator
KW  - cytosolic Ca2+ signals
KW  - OST1 protein kinase
KW  - R-GECO1-mTurquoise
KW  - SLAC1 and SLAH3 anion channels
KW  - stomata
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322716
VL  - 224
ER  - 
TY  - JOUR
A1  - Liu, Yi
A1  - Maierhofer, Tobias
A1  - Rybak, Katarzyna
A1  - Sklenar, Jan
A1  - Breakspear, Andy
A1  - Johnston, Matthew G.
A1  - Fliegmann, Judith
A1  - Huang, Shouguang
A1  - Roelfsema, M. Rob G.
A1  - Felix, Georg
A1  - Faulkner, Christine
A1  - Menke, Frank L.H.
A1  - Geiger, Dietmar
A1  - Hedrich, Rainer
A1  - Robatzek, Silke
T1  - Anion channel SLAH3 is a regulatory target of chitin receptor-associated kinase PBL27 in microbial stomatal closure
JF  - eLife
N2  - In plants, antimicrobial immune responses involve the cellular release of anions and are responsible for the closure of stomatal pores. Detection of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) induces currents mediated via slow-type (S-type) anion channels by a yet not understood mechanism. Here, we show that stomatal closure to fungal chitin is conferred by the major PRRs for chitin recognition, LYK5 and CERK1, the receptor-like cytoplasmic kinase PBL27, and the SLAH3 anion channel. PBL27 has the capacity to phosphorylate SLAH3, of which S127 and S189 are required to activate SLAH3. Full activation of the channel entails CERK1, depending on PBL27. Importantly, both S127 and S189 residues of SLAH3 are required for chitin-induced stomatal closure and anti-fungal immunity at the whole leaf level. Our results demonstrate a short signal transduction module from MAMP recognition to anion channel activation, and independent of ABA-induced SLAH3 activation.
KW  - plants
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-202631
VL  - 8
ER  -