Editors' ChoicePlant biology

Plants Interpret Climate Change

Science Signaling  16 Sep 2014:
Vol. 7, Issue 343, pp. ec251
DOI: 10.1126/scisignal.2005900

Global climate change is associated with increasing atmospheric CO2. Plants adapt to increased CO2 by reducing the number and aperture of stomatal cells, which form pores that participate in gas exchange and release water. Engineer et al. found that Arabidopsis thaliana with mutations in the genes encoding the carbonic anhydrases CA1 and CA4 increased the number of stomata per epidermal cell (stomatal index) in the leaves in response to increased CO2 concentrations. When grown in the presence of high CO2 concentrations, wild-type, but not CA1 CA4 double-mutant, plants increased the expression of EPF2, which encodes a secreted propeptide hormone. Plants with mutations in EPF2 had an increased stomatal index when grown in high CO2. EPF2 is cleaved by subtilisin-like proteases, and the abundance of the mRNA for one such protease CRSP (CO2 RESPONSE SECRETED PROTEASE) was increased in wild-type plants grown in high CO2. Plants with mutant CRSP had an increased stomatal index. In vitro, CRSP cleaved a synthetic peptide derived from EPF2. Overexpression of EPF2 decreased stomatal density more in wild-type plants than in CRSP-mutant plants. Thus, CA1, CA4, EPF2, and CRSP form part of a pathway that senses CO2 concentrations to regulate stomatal development. Understanding this pathway may be critical for agricultural adaptations to climate change.

C. B. Engineer, M. Ghassemian, J. C. Anderson, S. C. Peck, H. Hu, J. I. Schroeder, Carbonic anhydrases, EPF2 and a novel protease mediate CO2 control of stomatal development. Nature 513, 246–250 (2014). [PubMed]