title: Direct involvement of hydrogen peroxide in curvature of wheat coleoptile in blue-light-treated and dark-grown coleoptiles.
abstract: Blue-light-induced photomorphogenesis is the sum total of a sequence of phenomena involving absorption of light by specific receptors, generation of a signal, processing transmembrane transport of signal, and the activation of a cascade of reactions in the cell interior. Though four blue-light receptors cryptochrome1, cryptochrome2, phototropin1, and phototropin2 have been identified, the signal transduction events associated with blue-light receptor activation are not understood. In this report, we demonstrate the generation and spatiotemporal distribution of H(2)O(2) in wheat coleoptile in response to blue light. Interception of the free-radical generation pathways dithiothreitol and propyl gallate rendered wheat coleoptile tips phototropically non-responsive. Unilateral application of H(2)O(2) onto the sub-apical region of a growing coleoptile brought about curvature in dark. Blue light also caused lipid peroxidation and augmented membrane rigidity of coleoptile cell membranes. We conclude that H(2)O(2) can act as a translocating second messenger that could bring about coleoptile curvature, and the signaling events may trigger Ca(2+) signaling cascades, changes in gene expression, and protein modifications.
authors.affiliation: Molecular Reproduction Unit, School of Life Sciences, Devi Ahilya University, Vigyan Bhawan, Khandwa Road, Indore 452 017, M.P., India.
authors.forename: Kumar
authors.initials: K
authors.lastname: Chandrakuntal
authors.forename: Pradeep G
authors.initials: PG
authors.lastname: Kumar
authors.forename: Malini
authors.initials: M
authors.lastname: Laloraya
authors.forename: Manmohan M
authors.initials: MM
authors.lastname: Laloraya
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D018548:Cotyledon / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D003624:Darkness; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008027:Light; D016877:Oxidants / Q000494:pharmacology*; D018524:Phototropism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014908:Triticum / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects
chemical_list: D016877:Oxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide