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Open Access Highly Accessed Research article

Identification and characterization of circadian clock genes in a native tobacco, Nicotiana attenuata

Felipe Yon1, Pil-Joon Seo23, Jae Yong Ryu2, Chung-Mo Park2, Ian T Baldwin1 and Sang-Gyu Kim1*

  • * Corresponding author: Sang-Gyu Kim skim@ice.mpg.de

  • † Equal contributors

Author Affiliations

1 Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, Jena, D-07745, Germany

2 Department of Chemistry, Seoul National University, Seoul, 151-742, Korea

3 Department of Chemistry, Chonbuk National University, Jeonju, 561-756, Korea

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BMC Plant Biology 2012, 12:172  doi:10.1186/1471-2229-12-172

Published: 25 September 2012

Abstract

Background

A plant’s endogenous clock (circadian clock) entrains physiological processes to light/dark and temperature cycles. Forward and reverse genetic approaches in Arabidopsis have revealed the mechanisms of the circadian clock and its components in the genome. Similar approaches have been used to characterize conserved clock elements in several plant species. A wild tobacco, Nicotiana attenuata has been studied extensively to understand responses to biotic or abiotic stress in the glasshouse and also in their native habitat. During two decades of field experiment, we observed several diurnal rhythmic traits of N. attenuata in nature. To expand our knowledge of circadian clock function into the entrainment of traits important for ecological processes, we here report three core clock components in N. attenuata.

Results

Protein similarity and transcript accumulation allowed us to isolate orthologous genes of the core circadian clock components, LATE ELONGATED HYPOCOTYL (LHY), TIMING OF CAB EXPRESSION 1/PSEUDO-RESPONSE REGULATOR 1 (TOC1/PRR1), and ZEITLUPE (ZTL). Transcript accumulation of NaLHY peaked at dawn and NaTOC1 peaked at dusk in plants grown under long day conditions. Ectopic expression of NaLHY and NaZTL in Arabidopsis resulted in elongated hypocotyl and late-flowering phenotypes. Protein interactions between NaTOC1 and NaZTL were confirmed by yeast two-hybrid assays. Finally, when NaTOC1 was silenced in N. attenuata, late-flowering phenotypes under long day conditions were clearly observed.

Conclusions

We identified three core circadian clock genes in N. attenuata and demonstrated the functional and biochemical conservation of NaLHY, NaTOC1, and NaZTL.

Keywords:
Circadian clock; Flowering time; NaLHY; NaTOC1; NaZTL; Nicotiana attenuata; Protein interaction