Preflight Tests Of Vibration Sensitivity Of Arabidopsis Circumnutations
- Paper number
IAC-07-A2.4.02
- Author
Mr. Bjarte Gees Bokn Solheim, Norwegian University of Science and Technology, Norway
- Coauthor
Prof., fil.dr. Anders Johnsson, Norwegian University of Science and Technology, Norway
- Year
2007
- Abstract
During growth many plants perform synchronized, rotational movements around a reference direction, often the plumb line. The mechanisms of these movements, denoted circum - nutations, are not mapped in detail and the role played by gravitropism (or phototropism under certain experimental conditions) is not clarified. Johnsson (1997) reviews models for circumnutations and experimental evidences achieved in Space and on the Earth. The possibility of using microgravity in space vehicles to study circumnutations was early recognized (Johnsson and Heathcote) but only one space experiment has been performed (Brown et al. 1990). Circumnutations of sunflower hypocotyls were shown to circumnutate (although with changed period and amplitude) despite microgravity conditions. In the MULTIGEN-1 experiment, planned for July 2007 on the ISS, the growth of Arabidopsis plants will be studied in a seed to seed experiment (Solheim et al. 2006). The plants will be grown in the European Modular Cultivation System (EMCS) and time lapse video recordings should allow circumnutations to be observed during growth. The question about influences of vibrations on the circumnutations has not been satisfactorily studied. It can not a priori be excluded that mechanical vibrations initiate rhythmic growth by synchronizing cells in growing tissue also in free fall. It is of importance to perform relevant vibration test in pre-flight experiments. Arabidopsis plants were given an ISS analogue environment (same light, humidity etc. as on the ISS). However, 1 g is present in these pre-flight experiments. Vibration tests have been carried out and plant circumnutations recorded by 3D image sampling every 5 min. The plants were exposed to vertical mechanical vibrations for one hour at the developmental stage chosen. The amplitude of vibration is set fixed (4 mm peak to peak) while the frequency is swept from 0 to 30 Hz (repetition period 107 seconds), thus covering a band of vibration frequencies. Results indicate that Arabidopsis circumnutations might be affected by mechanical vibrations and show lengthened period. This would be in contrast to earlier reports from our laboratory indicating that sunflower hypocotyls can decrease their circumnutation period as well as amplitude after vibration at 15 Hz. Details of experiments and results will be presented.
References:
Brown A, Chapman DK, Lewis RF, Vendetti AL (1990). Circumnutations of sunflower hypocotyls in satellite orbit. Plant Physiol. 94:233-238.
Johnsson A (1997). Circumnutations: results from recent experiments on Earth and in space.- Planta 203: S147 – S158.
Johnsson A, Heathcote D (1973). Experimental evidence and models on circumnutations. Z. Pflanzenphysiologie 70: 371 – 405.
Solheim BGB, Kittang A-I, Iversen T-HI, Johnsson A (2006) Preparatory experiments for long-term observation of Arabidopsis circumnutations in microgravity. Acta astronautica 59: 46 – 53.
- Abstract document
- Manuscript document
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