title: Mesophyll photosynthesis and guard cell metabolism impacts on stomatal behaviour.
abstract: Stomata control gaseous fluxes between the internal leaf air spaces and the external atmosphere. Guard cells determine stomatal aperture and must operate to ensure an appropriate balance between CO2 uptake for photosynthesis (A) and water loss, and ultimately plant water use efficiency (WUE). A strong correlation between A and stomatal conductance (gs ) is well documented and often observed, but the underlying mechanisms, possible signals and metabolites that promote this relationship are currently unknown. In this review we evaluate the current literature on mesophyll-driven signals that may coordinate stomatal behaviour with mesophyll carbon assimilation. We explore a possible role of various metabolites including sucrose and malate (from several potential sources; including guard cell photosynthesis) and new evidence that improvements in WUE have been made by manipulating sucrose metabolism within the guard cells. Finally we discuss the new tools and techniques available for potentially manipulating cell-specific metabolism, including guard and mesophyll cells, in order to elucidate mesophyll-derived signals that coordinate mesophyll CO2 demands with stomatal behaviour, in order to provide a mechanistic understanding of these processes as this may identify potential targets for manipulations in order to improve plant WUE and crop yield.
authors: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors: Tracy
authors: T
authors: Lawson
authors: School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
authors: Andrew J
authors: AJ
authors: Simkin
authors: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet-Dagan, 50250, Israel.
authors: Gilor
authors: G
authors: Kelly
authors: Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet-Dagan, 50250, Israel.
authors: David
authors: D
authors: Granot
mesh_terms: D020346:Aquaporins / Q000378:metabolism; D058503:Mesophyll Cells / Q000502:physiology*; D064587:Osmoregulation; D010788:Photosynthesis; D054046:Plant Stomata / Q000166:cytology* / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D020346:Aquaporins
keywords: communication; guard cells; malate; mesophyll; mesophyll guard cell interactions; photosynthesis; stomata; sucrose