Gravity amplifies and microgravity decreases circumnutations in Arabidopsis thaliana stems: results from a space experiment

New Phytol. 2009;182(3):621-9. doi: 10.1111/j.1469-8137.2009.02777.x. Epub 2009 Mar 6.

Abstract

In a microgravity experiment onboard the International Space Station, circumnutations of Arabidopsis thaliana were studied. Plants were cultivated on rotors under a light:dark (LD) cycle of 16 : 8 h, and it was possible to apply controlled centrifugation pulses. Time-lapse images of inflorescence stems (primary, primary axillary and lateral inflorescences) documented the effect of microgravity on the circumnutations. Self-sustained circumnutations of side stems were present in microgravity but amplitudes were mostly very small. In darkness, centrifugation at 0.8 g increased the amplitude by a factor of five to ten. The period at 0.8 g was c. 85 min, in microgravity roughly of the same magnitude. In white light the period decreased to c. 60 min at 0.8 g (microgravity value not measurable). Three-dimensional data showed that under 0.8 g side stems rotated in both clockwise and counter-clockwise directions. Circumnutation data for the main stem in light showed a doubling of the amplitude and a longer period at 0.8 g than in microgravity (c. 80 vs 60 min). For the first time, the importance of gravity in amplifying minute oscillatory movements in microgravity into high-amplitude circumnutations was unequivocally demonstrated. The importance of these findings for the modelling of gravity effects on self-sustained oscillatory movements is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / growth & development*
  • Earth, Planet
  • Extraterrestrial Environment*
  • Gravitropism
  • Movement
  • Plant Stems / growth & development*
  • Rotation
  • Space Flight*
  • Time Factors
  • Weightlessness*