title: Increasing water-use efficiency directly through genetic manipulation of stomatal density.
abstract: Improvement in crop water-use efficiency (WUE) is a critical priority for regions facing increased drought or diminished groundwater resources. Despite new tools for the manipulation of stomatal development, the engineering of plants with high WUE remains a challenge. We used Arabidopsis epidermal patterning factor (EPF) mutants exhibiting altered stomatal density to test whether WUE could be improved directly by manipulation of the genes controlling stomatal density. Specifically, we tested whether constitutive overexpression of EPF2 reduced stomatal density and maximum stomatal conductance (gw(max) ) sufficiently to increase WUE. We found that a reduction in gw(max) via reduced stomatal density in EPF2-overexpressing plants (EPF2OE) increased both instantaneous and long-term WUE without altering significantly the photosynthetic capacity. Conversely, plants lacking both EPF1 and EPF2 expression (epf1epf2) exhibited higher stomatal density, higher gw(max) and lower instantaneous WUE, as well as lower (but not significantly so) long-term WUE. Targeted genetic modification of stomatal conductance, such as in EPF2OE, is a viable approach for the engineering of higher WUE in crops, particularly in future high-carbon-dioxide (CO2 ) atmospheres.
authors.affiliation: Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2006, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Franks
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: W Doheny-Adams
authors.affiliation: Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2006, Australia.
authors.forename: Zoe J
authors.initials: ZJ
authors.lastname: Britton-Harper
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK.
authors.forename: Julie E
authors.initials: JE
authors.lastname: Gray
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D009929:Organ Size; D010788:Photosynthesis; D054046:Plant Stomata / Q000033:anatomy & histology / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D014867:Water / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C542689:EPF2 protein, Arabidopsis; D014157:Transcription Factors; D014867:Water
keywords: Arabidopsis; carbon dioxide (CO2); crops; epidermal patterning factor (EPF); genetically modified water-use efficiency (WUE); stomata; δ13C