title: Development of the Casparian strip is delayed by blue light in pea stems.
abstract: To understand the regulatory mechanisms involved in tissue development by light, the kinetics of regulation of Casparian strip (CS) development in garden pea stems was studied. We found that short-term irradiation with white light delayed the development of the CS and used this delay to assess the quantitative effect of light on CS development. We examined the effect of the duration and fluence rates of white light treatment on CS development and observed a significant relationship between fluence and the delay in CS development indicating that the Bunsen-Roscoe law of reciprocity holds for this response. The effect of white light irradiation was not inhibited in the presence of a photosynthetic inhibitor, DCMU, or a carotenoid biosynthesis inhibitor, Norflurazon, indicating that the delay in CS development by light is a photomorphogenetic response rather than a subsidiary effect mediated by photosynthetic activity. An action spectrum for the response displayed a major peak in the blue-light region, suggesting a dominant role for blue-light receptors. A minor peak in the red-light region also suggested the possible involvement of phytochromes. Although phytochromes are known to contribute to blue-light responses, phytochrome-deficient mutants showed a normal delay of CS development in response to blue light, indicating that the response is not mediated by phytochrome and suggesting a role for one or more specific blue-light receptors.
authors.affiliation: Department of Biology, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan. karahara@sci.u-toyama.ac.jp
authors.forename: Ichirou
authors.initials: I
authors.lastname: Karahara
authors.forename: Eliko
authors.initials: E
authors.lastname: Takaya
authors.forename: Shigetaka
authors.initials: S
authors.lastname: Fujibayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
authors.forename: James L
authors.initials: JL
authors.lastname: Weller
authors.forename: James B
authors.initials: JB
authors.lastname: Reid
authors.forename: Michizo
authors.initials: M
authors.lastname: Sugai
mesh_terms: D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism; D004237:Diuron / Q000494:pharmacology; D005453:Fluorescence; D008027:Light; D008353:Mannitol / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D018532:Pisum sativum / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D010788:Photosynthesis; D018517:Plant Roots / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D018547:Plant Stems / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects*; D011724:Pyridazines / Q000494:pharmacology
chemical_list: D011724:Pyridazines; D002734:Chlorophyll; D008353:Mannitol; D004237:Diuron; C008677:norflurazone