Auxin/Cytokinin Antagonistic Control of the Shoot/Root Growth Ratio and Its Relevance for Adaptation to Drought and Nutrient Deficiency Stresses

Jasmina Kurepa, Jan A. Smalle

Research output: Contribution to journalReview articlepeer-review

26 Scopus citations


The hormones auxin and cytokinin regulate numerous aspects of plant development and often act as an antagonistic hormone pair. One of the more striking examples of the auxin/cytokinin antagonism involves regulation of the shoot/root growth ratio in which cytokinin promotes shoot and inhibits root growth, whereas auxin does the opposite. Control of the shoot/root growth ratio is essential for the survival of terrestrial plants because it allows growth adaptations to water and mineral nutrient availability in the soil. Because a decrease in shoot growth combined with an increase in root growth leads to survival under drought stress and nutrient limiting conditions, it was not surprising to find that auxin promotes, while cytokinin reduces, drought stress tolerance and nutrient uptake. Recent data show that drought stress and nutrient availability also alter the cytokinin and auxin signaling and biosynthesis pathways and that this stress-induced regulation affects cytokinin and auxin in the opposite manner. These antagonistic effects of cytokinin and auxin suggested that each hormone directly and negatively regulates biosynthesis or signaling of the other. However, a growing body of evidence supports unidirectional regulation, with auxin emerging as the primary regulatory component. This master regulatory role of auxin may not come as a surprise when viewed from an evolutionary perspective.

Original languageEnglish
Article number1933
JournalInternational Journal of Molecular Sciences
Issue number4
StatePublished - Feb 1 2022

Bibliographical note

Funding Information:
Funding: The work was supported by The Kentucky Tobacco Research and Development Center, and by NIFA HATCH project (1009329).

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.


  • Auxin signaling
  • Auxin/cytokinin signaling crosstalk
  • Cytokinin signaling
  • Drought stress
  • Hormone antagonism
  • Nutrient deficiency
  • Shoot/root growth ratio

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Spectroscopy
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry


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