Cytokinin inhibits lateral root initiation but stimulates lateral root elongation in rice (Oryza sativa)

Bakul Rani Debi, Shin Taketa, Masahiko Ichii

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63 Citations (Scopus)

Abstract

Research in lateral root (LR) development mainly focuses on the role of auxin. This article reports the effect of cytokinins (kinetin and trans-zeatin) on LR formation in rice (Oryza sativa L.). Our results showed that cytokinin has an inhibitory effect on LR initiation and stimulatory effect on LR elongation. Both KIN and ZEA at a concentration of 1 μM and above completely inhibited lateral root primordium (LRP) formation. The inhibitory effect of cytokinin on LR initiation required a continuous presence of KIN or ZEA in the growth solution. Cytokinin did not show any inhibitory effect on LR emergence from the seminal root once LRPs had been formed. The LRPs that developed in cytokinin-free solution can emerge normally in the solution containing inhibitory concentration (1 μM) of KIN and ZEA. The KIN and ZEA treatment dramatically stimulated LR elongation at all the concentrations tested. Maximum LR elongation was observed at a concentration of 0.01 μM KIN and 0.001 μM ZEA. The epidermal cell length increased significantly in LRs of cytokinin treated seedlings compared to those of untreated control. This result indicates that the stimulation of LR elongation by cytokinin is due to increased cell length. Exogenously applied auxin counteracted the effect of cytokinin on LR initiation and LR elongation, suggesting that cytokinin acts on LR elongation through an auxin dependent pathway.

Original languageEnglish
Pages (from-to)507-515
Number of pages9
JournalJournal of Plant Physiology
Volume162
Issue number5
DOIs
Publication statusPublished - May 13 2005
Externally publishedYes

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Keywords

  • Cytokinin
  • Inhibition
  • Lateral root
  • Rice
  • Stimulation

ASJC Scopus subject areas

  • Physiology
  • Agronomy and Crop Science
  • Plant Science

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