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Guard-cell-targeted overexpression of Arabidopsis Hexokinase 1 can improve water use efficiency in field-grown tobacco plants.

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Acevedo-Siaca, Liana G  ORCID logo
Głowacka, Katarzyna 
Salesse-Smith, Coralie E  ORCID logo


Water deficit currently acts as one of the largest limiting factors for agricultural productivity worldwide. Additionally, limitation by water scarcity is projected to continue in the future with the further onset of effects of global climate change. As a result, it is critical to develop or breed for crops that have increased water use efficiency and that are more capable of coping with water scarce conditions. However, increased intrinsic water use efficiency (iWUE) typically brings a trade-off with CO2 assimilation as all gas exchange is mediated by stomata, through which CO2 enters the leaf while water vapor exits. Previously, promising results were shown using guard-cell-targeted overexpression of hexokinase to increase iWUE without incurring a penalty in photosynthetic rates or biomass production. Here, two homozygous transgenic tobacco (Nicotiana tabacum) lines expressing Arabidopsis Hexokinase 1 (AtHXK1) constitutively (35SHXK2 and 35SHXK5) and a line that had guard-cell-targeted overexpression of AtHXK1 (GCHXK2) were evaluated relative to wild type for traits related to photosynthesis and yield. In this study, iWUE was significantly higher in GCHXK2 compared with wild type without negatively impacting CO2 assimilation, although results were dependent upon leaf age and proximity of precipitation event to gas exchange measurement.



CO2 assimilation, hexokinase, photosynthesis, water use efficiency, Arabidopsis, Carbon Dioxide, Hexokinase, Photosynthesis, Plant Breeding, Plant Leaves, Nicotiana

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J Exp Bot

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Oxford University Press (OUP)
Bill & Melinda Gates Foundation (088649-17776)
Bill & Melinda Gates Foundation (via University Of Illinois) (088649-17776)
This work was supported by the project Realizing Increased Photosynthetic Efficiency (RIPE), that is funded by the Bill & Melinda Gates Foundation, Foundation for Food and Agriculture Research (FFAR), and the UK Foreign Commonwealth and Development Office under grant number OPP1172157.