Cytokinin activity increases stomatal density and transpiration rate in tomato

Mika Farber, Ziv Attia, David Weiss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


Previous studies on cytokinin (CK) and drought have suggested that the hormone has positive and negative effects on plant adaptation to restrictive conditions. This study examined the effect of CK on transpiration, stomatal activity, and response to drought in tomato (Solanum lycopersicum) plants. Transgenic tomato plants overexpressing the Arabidopsis thaliana CK-degrading enzyme CK oxidase/dehydrogenase 3 (CKX3) maintained higher leaf water status under drought conditions due to reduced whole-plant transpiration. The reduced transpiration could be attributed to smaller leaf area and reduced stomatal density. CKX3-overexpressing plants contained fewer and larger pavement cells and fewer stomata per leaf area than wild-type plants. In addition, wild-type leaves treated with CK exhibited enhanced transpiration and had more pavement cells and increased numbers of stomata per leaf area than untreated leaves. Manipulation of CK levels did not affect stomatal movement or abscisic acid-induced stomatal closure. Moreover, we found no correlation between stomatal aperture and the activity of the CK-induced promoter Two-Component Signaling Sensor (TCS) in guard cells. Previous studies have shown that drought reduces CK levels, and we propose this to be a mechanism of adaptation to water deficiency: the reduced CK levels suppress growth and reduce stomatal density, both of which reduce transpiration, thereby increasing tolerance to prolonged drought conditions.

Original languageAmerican English
Pages (from-to)6351-6362
Number of pages12
JournalJournal of Experimental Botany
Issue number22
StatePublished - Dec 2016

Bibliographical note

Publisher Copyright:
© The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.


  • Cytokinin
  • Drought
  • Stomata
  • Stomatal density
  • Tomato
  • Transpiration


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