THRESHOLD ACCELERATION FOR GRAVISENSING-1 (GRAVI-1)
Research Area: Plant Biology
Expedition(s): 14
Principal Investigator(s): ● Dominique Driss-Ecole, PhD, Université Pierre-et-Marie Curie,
Paris, FranceRESEARCH OBJECTIVES
Threshold Acceleration for Gravisensing-1 (Gravi-1) grows lentil seedling roots under various
gravity conditions aboard the International Space Station (ISS) to determine the amount of
acceleration force sufficient to stimulate the direction of root growth. In the first part of the
experiment, seedlings are grown in weightlessness following hydration for 15 hours and then
centrifuged for almost 14 hours. In the second part of the experiment, seedlings are grown for
21.5 hours in weightlessness followed by 9 hours of induced gravity by centrifuge.EARTH BENEFITS
These goals will provide insight into the fundamental organization and operation of the gravity
response system of plants and determine if, other than the root cap, other parts of the plant
require cues for directional growth.SPACE BENEFITS
Although this is primarily a basic research study, understanding how plants respond to partial
gravity environments may be useful for growing plants on the moon or Mars.RESULTS
The imagery showed that the
embryonic roots curved away
from the cotyledons and then
slowly straightened from 17 hours
to 30 hours after hydration. Due
to this straightening the root tip
was oriented close to an optimal
angle of curvature (120-135°)
during a 2-hour period of
centrifugation. One interesting
point is that lentil roots grown in
weightlessness were more
sensitive to stimulation than lentil roots grown under 1-g conditions. The gravity threshold
perceived by these plants was determined to be between 0 and 0.002g. In addition by using a
hyperbolic model, the gravity threshold was estimated to be 1.4 x 10-5 g.Cultivation chambers from the Gravi-1 experiment in the US laboratory,
carries out research to determine the gravity perception threshold in
lentil seedlings. NASA image.