Induction of myrosinase gene expression and myrosinase activity in radish hypocotyls by phototropic stimulation

Kosumi Yamada, Tsuyoshi Hasegawa, Eiichi Minami, Naoto Shibuya, Seiji Kosemura, Shosuke Yamamura, Koji Hasegawa

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


The role of myrosinase (β-thioglucoside glucohydrolase, EC in the phototropic response in radish hypocotyls was investigated. Unilateral illumination with blue light abruptly up-regulated the activity of myrosinase, which releases bioactive 4-methylthio-3-butenyl isothiocyanate (MTBI) from inactive 4-methylthio-3-butenyl glucosinolate (MTBG), in the illuminated halves of radish hypocotyls 10 min after onset of phototropic stimulation, peaking after 30 min and decreasing thereafter. The myrosinase activity in the shaded halves also increased, but was significantly lower than that in the illuminated halves. Furthermore, whether blue light illumination induces myrosinase gene expression was studied. Northern blotting analysis indicated that myrosinase mRNA levels were increased markedly in unilaterally illuminated hypocotyls, reaching maximum signal intensity within 10 min after onset of blue illumination, declining nearly to the control level thereafter. These results suggested that phototropic stimulation promotes myrosinase gene expression and myrosinase activity in the illuminated side, resulting in the conversion of inactive MTBG to active MTBI and simultaneously producing more active raphanusanins, causing a phototropic response.

Original languageEnglish
Pages (from-to)255-259
Number of pages5
JournalJournal of Plant Physiology
Issue number3
Publication statusPublished - 2003 Mar 1
Externally publishedYes


  • 3-(Methylthio) methylene-2-pyrrolidinethione
  • 4-Methylthio-3-butenyl isothiocyanate
  • Glucosinolate
  • Growth inhibitor
  • Myrosinase
  • Phototropism
  • Radish hypocotyl
  • Raphanusanin

ASJC Scopus subject areas

  • Physiology
  • Agronomy and Crop Science
  • Plant Science


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