Stomatal Pore Density

Abstract

As atmospheric CO 2 concentration increases, the density of stomatal pores on the leaf surface decreases to prevent loss of water during transpiration. An analysis of mutants by Gray et al. reveals that a gene in the plant Arabidposis thaliana called high carbon dioxide ( HIC ) may be responsible for regulating stomatal development in response to CO 2 . HIC , expressed exclusively in guard cells that flank stomatal pores, encodes a putative 3-keto acyl coenzyme A synthase, an enzyme involved in synthesizing long-chain fatty acids that comprise components of the extracellular matrix found at the surface of guard cells. When HIC expression is disrupted, plants can no longer respond to increases in CO 2 . The authors propose that absence of the HIC -encoded enzyme could alter the composition of the extracellular matrix and thus affect diffusion of CO 2 -regulated morphogens that regulate stomatal development. Gray, J.E., Holroyd, G.H., Van der Lee, F.M., Bahrami, A.R., Sijmons, P.C., Woodward, F.I., Schuch, W., and Hetherington, A.M. (2000) The HIC signalling pathway links CO 2 perception to stomatal development. Nature 408 : 713-716. [Online Journal]