J Integr Plant Biol. ›› 2017, Vol. 59 ›› Issue (8): 572-587.DOI: 10.1111/jipb.12547

• Plant-environmental Interactions • Previous Articles    

Circadian clock component, LHY, tells a plant when to respond photosynthetically to light in nature

Youngsung Joo, Variluska Fragoso, Felipe Yon, Ian T. Baldwin* and Sang-Gyu Kim*   

  1. Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, D-07745 Jena, Germany
  • Received:2016-01-25 Accepted:2017-04-18 Published:2017-04-21
  • About author:Current address: Center for Genome Engineering, Institute for Basic Science, Yuseong-gu, Daejeon, 34047, South Korea
    **Correspondences: E-mail: Ian T. Baldwin (baldwin@ice.mpg.de, Dr. Baldwin is fully responsible for the distribution of all materials associated with this article), Sang-Gyu Kim (sgkim@ibs.re.kr)


The circadian clock is known to increase plant growth and fitness, and is thought to prepare plants for photosynthesis at dawn and dusk; whether this happens in nature was unknown. We transformed the native tobacco, Nicotiana attenuata to silence two core clock components, NaLHY (irLHY) and NaTOC1 (irTOC1). We characterized growth and light- and dark-adapted photosynthetic rates (Ac) throughout a 24 h day in empty vector-transformed (EV), irLHY, and irTOC1 plants in the field, and in NaPhyA- and NaPhyB1-silenced plants in the glasshouse. The growth rates of irLHY plants were lower than those of EV plants in the field. While irLHY plants reduced Ac earlier at dusk, no differences between irLHY and EV plants were observed at dawn in the field. irLHY, but not EV plants, responded to light in the night by rapidly increasing Ac. Under controlled conditions, EV plants rapidly increased Ac in the day compared to dark-adapted plants at night; irLHY plants lost these time-dependent responses. The role of NaLHY in gating photosynthesis is independent of the light-dependent reactions and red light perceived by NaPhyA, but not NaPhyB1. In summary, the circadian clock allows plants not to respond photosynthetically to light at night by anticipating and gating red light-mediated in native tobacco.

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