Light/Dark Responsiveness of Kinetin-Inducible Secondary Metabolites and Stress Proteins in Rice Leaf

  • Cho, Kyoung-Won (Environmental Biology Division, National Institute for Environmental Studies(NIES)) ;
  • Kim, Dea-Wook (National Institute of Crop Science, Rural Development Administration) ;
  • Jung, Young-Ho (Department of Molecular Biology, College of Natural Science, Sejong University) ;
  • Shibato, Junko (Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology) ;
  • Tamogami, Shigeru (Laboratory of Growth Regulation Chemistry, Department of Biological Production, Akita Prefectural University) ;
  • Yonekura, Masami (Food Function Laboratory, School of Agriculture, Ibaraki University) ;
  • Jwa, Nam-Soo (Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology) ;
  • Kubo, Akihiro (Environmental Biology Division, National Institute for Environmental Studies(NIES)) ;
  • Agrawal, Ganesh Kumar (Research Laboratory for Agricultural Biotechnology and Biochemistry) ;
  • Rakwal, Randeep (Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology)
  • Published : 2007.06.30

Abstract

Kinetin(KN) is an inducer of rice(Oryza sativa L.) defense/stress responses, as evidenced by the induction of inducible secondary metabolite and defense/stress protein markers in leaf. We show a novel light-dependent effect of KN-triggered defense stress responses in rice leaf. Leaf segments treated with KN(100 ${\mu}M$) show hypersensitive-like necrotic lesion formation only under continuous light illumination. Potent accumulation of two phytoalexins, sakuranetin and momilactone A(MoA) by KN that peaks at 48 h after treatment under continuous light is completely suppressed by incubation under continuous dark. Using two-dimensional gel electrophoresis we identified KN-induced changes in ribulose-1, 5-bisphosphate carboxylase/oxygenase, energy- and pathogenesis-related proteins(OsPR class 5 and 10 members) by N-terminal amino acid sequencing and mass spectrometry. These changes were light-inducible and could not be observed in the dark(and control). Present results provide a new dimension(light modulation/regulation) to our finding that KN has a potential role in the rice plant self-defense mechanism.