Rethinking Guard Cell Metabolism.
Stomata control gaseous fluxes between the internal leaf air spaces and the external atmosphere and, therefore, play a pivotal role in regulating CO2uptake for photosynthesis as well as water loss through transpiration. Guard cells, which flank the stomata, undergo adjustments in volume, resulting in changes in pore aperture. Stomatal opening is mediated by the complex regulation of ion transport and solute biosynthesis. Ion transport is exceptionally well understood, whereas our knowledge of guard cell metabolism remains limited, despite several decades of research. In this review, we evaluate the current literature on metabolism in guard cells, particularly the roles of starch, sucrose, and malate. We explore the possible origins of sucrose, including guard cell photosynthesis, and discuss new evidence that points to multiple processes and plasticity in guard cell metabolism that enable these cells to function effectively to maintain optimal stomatal aperture. We also discuss the new tools, techniques, and approaches available for further exploring and potentially manipulating guard cell metabolism to improve plant water use and productivity.
Department of Plant and Microbial Biology, University of Zürich, 8008 Zurich, Switzerland (D.S.); and dsantelia@botinst.uzh.ch.|School of Biological Science, University of Essex, Colchester CO4 3SQ, United Kingdom (T.L.) dsantelia@botinst.uzh.ch.
Diana
0000-0001-9686-1216
D
Santelia
Department of Plant and Microbial Biology, University of Zürich, 8008 Zurich, Switzerland (D.S.); and.|School of Biological Science, University of Essex, Colchester CO4 3SQ, United Kingdom (T.L.).
Tracy
0000-0002-4073-7221
T
Lawson
D002244:Carbon / Q000378:metabolism; D002264:Carboxylic Acids / Q000378:metabolism; D010788:Photosynthesis; D054046:Plant Stomata / Q000166:cytology* / Q000378:metabolism*; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
D002264:Carboxylic Acids; D013395:Sucrose; D002244:Carbon; D013213:Starch