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Induction of myrosinase gene expression and myrosinase activity in radish hypocotyls by phototropic stimulation.
Yamada, Kosumi; Hasegawa, Tsuyoshi; Minami, Eiichi; Shibuya, Naoto; Kosemura, Seiji; Yamamura, Shosuke; Hasegawa, Koji.
Affiliation
  • Yamada K; Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan. kosumi@sakura.cc.tsukuba.ac.jp
J Plant Physiol ; 160(3): 255-9, 2003 Mar.
Article in En | MEDLINE | ID: mdl-12749082
ABSTRACT
The role of myrosinase (beta-thioglucoside glucohydrolase, EC 3.2.3.1) 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.
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Collection: 01-internacional Database: MEDLINE Main subject: Phototropism / Hypocotyl / Raphanus / Glycoside Hydrolases Language: En Journal: J Plant Physiol Journal subject: BOTANICA Year: 2003 Document type: Article Affiliation country:
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Collection: 01-internacional Database: MEDLINE Main subject: Phototropism / Hypocotyl / Raphanus / Glycoside Hydrolases Language: En Journal: J Plant Physiol Journal subject: BOTANICA Year: 2003 Document type: Article Affiliation country: