OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) OA All Versions of this Article: 148/2/1082    most recent pp.108.122275v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Zubo, Y. O. Articles by Börner, T. Search for Related Content PubMed PubMed Citation Articles by Zubo, Y. O. Articles by Börner, T. Agricola Articles by Zubo, Y. O. Articles by Börner, T.

DEVELOPMENT AND HORMONE ACTION

Cytokinin Stimulates Chloroplast Transcription in Detached Barley Leaves^1,[OA]

Timiriazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, 127276 Russia (Y.O.Z., M.V.Y., S.Y.S., N.V.K., N.K.Z., O.N.K., V.V.K.); Institute of Biochemistry and Genetics, Ufa Research Center, Russian Academy of Sciences, Ufa, 450054 Russia (F.M.S., A.M.A.); and Institute of Biology, Humboldt University, D–10115 Berlin, Germany (Y.O.Z., K.L., T.B.)

Chloroplasts are among the main targets of cytokinin action in the plant cell. We report here on the activation of transcription by cytokinin as detected by run-on assays with chloroplasts isolated from apical parts of first leaves detached from 9-d-old barley (Hordeum vulgare) seedlings and incubated for 3 h on a 2.2 x 10^–5 M solution of benzyladenine (BA). Northern-blot analysis also detected a BA-induced increase in the accumulation of chloroplast mRNAs. A prerequisite for BA activation of chloroplast transcription was preincubation of leaves for 24 h on water in the light, resulting in a decreased chloroplast transcription and a drastic accumulation of abscisic acid. Cytokinin enhanced the transcription of several chloroplast genes above the initial level measured before BA treatment, and in the case of rrn16 and petD even before preincubation. Cytokinin effects on basal (youngest), middle, and apical (oldest) segments of primary leaves detached from plants of different ages revealed an age dependence of chloroplast gene response to BA. BA-induced stimulation of transcription of rrn16, rrn23, rps4, rps16, rbcL, atpB, and ndhC required light during the period of preincubation and was further enhanced by light during the incubation on BA, whereas activation of transcription of trnEY, rps14, rpl16, matK, petD, and petLG depended on light during both periods. Our data reveal positive and differential effects of cytokinin on the transcription of chloroplast genes that were dependent on light and on the age (developmental stage) of cells and leaves.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Thomas Börner (thomas.boerner{at}rz.hu-berlin.de).

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.108.122275

^* Corresponding author; e-mail thomas.boerner{at}rz.hu-berlin.de.

Received April 30, 2008; accepted August 11, 2008; published August 20, 2008.