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Gravity amplifies and microgravity decreases circumnutations in Arabidopsis thaliana stems: results from a space experiment
Author(s) -
Johnsson A.,
Solheim B. G. B.,
Iversen T.H.
Publication year - 2009
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2009.02777.x
Subject(s) - arabidopsis thaliana , weightlessness , physics , space (punctuation) , astrobiology , gravitropism , biology , arabidopsis , botany , environmental science , astronomy , computer science , gene , mutant , operating system , biochemistry
Summary• 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.