Expression of Arabidopsis hexokinase in citrus guard cells controls stomatal aperture and reduces transpiration

Nitsan Lugassi, Gilor Kelly, Lena Fidel, Yossi Yaniv, Ziv Attia, Asher Levi, Victor Alchanatis, Menachem Moshelion, Eran Raveh, Nir Carmi, David Granot*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Hexokinase (HXK) is a sugar-phosphorylating enzyme involved in sugar-sensing. It has recently been shown that HXK in guard cells mediates stomatal closure and coordinates photosynthesis with transpiration in the annual species tomato and Arabidopsis. To examine the role of HXK in the control of the stomatal movement of perennial plants, we generated citrus plants that express Arabidopsis HXK1 (AtHXK1) under KST1, a guard cell-specific promoter. The expression of KST1 in the guard cells of citrus plants has been verified using GFP as a reporter gene. The expression of AtHXK1 in the guard cells of citrus reduced stomatal conductance and transpiration with no negative effect on the rate of photosynthesis, leading to increased water-use efficiency. The effects of light intensity and humidity on stomatal behavior were examined in rooted leaves of the citrus plants. The optimal intensity of photosynthetically active radiation and lower humidity enhanced stomatal closure of AtHXK1 -expressing leaves, supporting the role of sugar in the regulation of citrus stomata. These results suggest that HXK coordinates photosynthesis and transpiration and stimulates stomatal closure not only in annual species, but also in perennial species.

Original languageAmerican English
Article number1114
JournalFrontiers in Plant Science
Volume6
Issue numberDEC
DOIs
StatePublished - 16 Dec 2015

Bibliographical note

Publisher Copyright:
© 2015 Lugassi, Kelly, Fidel, Yaniv, Attia, Levi, Alchanatis, Moshelion, Raveh, Carmi and Granot.

Keywords

  • Citrus rooted leaves
  • Hexokinase
  • Humidity
  • Light intensity
  • Stomata
  • Sugar
  • Transpiration
  • Water-use efficiency

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