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A tandem amino acid residue motif in guard cell SLAC1 anion channel of grasses allows for the control of stomatal aperture by nitrate.
Curr. Biol. 28, 1370-U145 (2018)
The latest major group of plants to evolve were the grasses. These became important in the mid-Paleogene about 40 million years ago. During evolution, leaf CO2uptake and transpirational water loss were optimized by the acquisition of grass-specific stomatal complexes. In contrast to the kidney-shaped guard cells (GCs) typical of the dicots such as Arabidopsis, in the grasses and agronomically important cereals, the GCs are dumbbell shaped and are associated with morphologically distinct subsidiary cells (SCs). We studied the molecular basis of GC action in the major cereal crop barley. Upon feeding ABA to xylem sap of an intact barley leaf, stomata closed in a nitrate-dependent manner. This process was initiated by activation of GC SLAC-type anion channel currents. HvSLAC1 expressed in Xenopus oocytes gave rise to S-type anion currents that increased several-fold upon stimulation with >3 mM nitrate. We identified a tandem amino acid residue motif that within the SLAC1 channels differs fundamentally between monocots and dicots. When the motif of nitrate-insensitive dicot Arabidopsis SLAC1 was replaced by the monocot signature, AtSLAC1 converted into a grass-type like nitrate-sensitive channel. Our work reveals a fundamental difference between monocot and dicot GCs and prompts questions into the selective pressures during evolution that resulted in fundamental changes in the regulation of SLAC1 function. Schäfer et al. report that guard cells of the cereal crop barley require nitrate for ABA-induced stomatal closure—a feature accomplished by the guard cell anion channel HvSLAC1. Nitrate-dependent gating of HvSLAC1 and other monocot SLAC1-type anion channels evolved from a TMD3 tandem motif after the split between monocots and dicots.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
Aba-signaling ; Barley ; Guard Cells ; Hordeum Volgare ; Nitrate Activated Anion Channel ; S-type Anion Channel ; Slac1 ; Stomata
Language
english
Publication Year
2018
HGF-reported in Year
2018
ISSN (print) / ISBN
0960-9822
e-ISSN
1879-0445
Journal
Current Biology
Quellenangaben
Volume: 28,
Issue: 9,
Pages: 1370-U145
Publisher
Elsevier
Reviewing status
Peer reviewed
POF-Topic(s)
30202 - Environmental Health
Research field(s)
Environmental Sciences
PSP Element(s)
G-503500-002
WOS ID
WOS:000432442300021
Scopus ID
85045892867
PubMed ID
29706511
Erfassungsdatum
2018-06-08