A molecular pathway for CO2 response in stomata


A molecular pathway for CO2 response in Arabidopsis guard cells.

by Tian W., Hou C., Ren Z., Pan Y., Jia J., Zhang H., Bai F., Zhang P., Zhu H., He Y., Luo S., Li L., Luan S. (2015)

in Nat. Commun. 6:6057. – doi: 10.1038/ncomms7057 –

PubMed Abstract | CrossRef Full Text | Google Scholar – 


(a–e) Expression of RHC1::GUS in leaves (a), flowers (b), vascular systems (c), stem (d) and guard cells (e). Scale bars, 500 μm (a,b), 100 μm (c,d), 5 μm (e). (f) Subcellular localization of RHC1 in Arabidopsis mesophyll protoplasts. 35S::RHC1–GFP, 35S::SLAC1–GFP and 35S::GFP were transiently expressed in Arabidopsis mesophyll protoplasts, respectively. SLAC1–GFP fusion was used as a control for plasma membrane localization and GFP alone was used as a control for cytosol and nuclear localization. Scale bars, 5 μm. (g) Time courses of stomatal conductance in response to changes in CO2 concentration in wild-type (WT), rhc1 mutants and a complementation line (comp). Stomatal conductance was measured using a gas-exchange system. The leaves were stabilized in 400 p.p.m. CO2 before changing to 800 p.p.m. CO2. Values of stomatal conductance at 400 p.p.m. CO2 were normalized to 1. (n=5 leaves for rhc1, n=4 for WT and n=3 for the complemented line.) Data are presented as means±s.e.m. (h) High [CO2]-induced stomatal closing is impaired in rhc1 mutant leaf epidermis. Leaf epidermis were treated with 800 p.p.m. CO2 for 30 min (n=3 experiments, 60 stomata per condition, genotype blind analyses; *P<0.001, pairwise Student’s t-test). (i) Stomata in rhc1 leaves close in response to abscisic acid (ABA). Leaf epidermis were treated with 0, 1, 10 and 50 μM ABA for 30 min (n=3 experiments, 60 stomata per condition). (j) Stomata in rhc1 leaves close in response to CaCl2. Leaf epidermis were treated with 0, 2 and 10 mM CaCl2 for 120 min (n=3 experiments, 60 stomata per condition). Data in h–j are presented as means±s.e.m.


Increasing carbon dioxide (CO2) levels in the atmosphere have caused global metabolic changes in diverse plant species. CO2 is not only a carbon donor for photosynthesis but also an environmental signal that regulates stomatal movements and thereby controls plant–water relationships and carbon metabolism. However, the mechanism underlying CO2 sensing in stomatal guard cells remains unclear.

Here we report characterization of Arabidopsis RESISTANT TO HIGH CO2(RHC1), a MATE-type transporter that links elevated CO2 concentration to repression of HT1, a protein kinase that negatively regulates CO2-induced stomatal closing.

We also show that HT1 phosphorylates and inactivates OST1, a kinase which is essential for the activation of the SLAC1 anion channel and stomatal closing.

Combining genetic, biochemical and electrophysiological evidence, we reconstituted the molecular relay from CO2 to SLAC1 activation, thus establishing a core pathway for CO2 signalling in plant guard cells.


Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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