Journal Article

Aberrant Expression of the Light-Inducible and Circadian-Regulated <i>APRR9</i> Gene Belonging to the Circadian-Associated APRR1/TOC1 Quintet Results in the Phenotype of Early Flowering in <i>Arabidopsis thaliana</i>

Akinori Matsushika, Aya Imamura, Takafumi Yamashino and Takeshi Mizuno

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 8, pages 833-843
Published in print August 2002 | ISSN: 0032-0781
Published online August 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf118
Aberrant Expression of the Light-Inducible and Circadian-Regulated APRR9 Gene Belonging to the Circadian-Associated APRR1/TOC1 Quintet Results in the Phenotype of Early Flowering in Arabidopsis thaliana

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Several Arabidopsis genes have been proposed to encode potential clock-associated components, including the Myb-related CCA1 and LHY transcription factors and a member (APRR1/TOC1) of the family of pseudo-response regulators. We previously showed that transcripts of the APRR1/TOC1 family genes each start accumulating after dawn rhythmically and sequentially at intervals in the order of APRR9→APRR7→APRR5→APRR3→APRR1/TOC1, under the conditions of continuous light. Nevertheless, no evidence has been provided that each member of the APRR1/TOC1 quintet, except for APRR1/TOC1, is indeed relevant to the mechanisms underlying circadian rhythms. Here we attempt to provide such evidence by characterizing transgenic plants that aberrantly (or constitutively) express the APRR9 gene in a manner independent of circadian rhythms. The resulting APRR9-ox plants showed intriguing phenotypes with regard to circadian rhythms, in two aspects. First, the aberrant expression of APRR9 resulted in a characteristic phenotype with regard to transcriptional events, in which short-period rhythms were commonly observed for certain circadian-regulated genes, including CCA1, LHY, APRR1/TOC1, other APRR1/TOC1 members, ELF3, and CAB2. With regard to biological consequences, such APRR9-ox plants flowered much earlier than wild-type plants, in a manner independent of photoperiodicity (or under short-day conditions). These results suggest that APRR9 (and perhaps other members of the APRR1/TOC1 quintet) must also be taken into consideration for a better understanding of the molecular mechanisms underlying circadian rhythms, and also underlying control of the flowering time through the photoperiodic long-day pathway.

Keywords: Keywords: Arabidopsis — Circadian rhythm — Clock components — Transgenic plants.

Journal Article.  7507 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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