space BOTANY in LIThUANIA. II. study on root gravity sensing during satellite “Bion-11” flight

This paper addresses the space experiments performed on board of the unmanned satellite “Bion-11” in 1997. To detail root gravity sensing in stimulus-free microgravity environment, researchers from the Institute of Botany developed an automatically operating centrifuge “Neris-8” to grow garden cress seedlings and to chemically fix them at the end of the experiments. There was examined behaviour of gravity sensors – amyloplasts within cap cells of roots responding to stimulation by artificial fractional gravity. The static of amyloplasts was determined in roots after continuous growth for 25 h in microgravity, 0.005, 0.02, 0.1 and 1-g environment. The movement kinetics of amyloplasts was studied in roots during the exposition to microgravity after 24-h growth in 1-g environment or conversely. Quantitative study on the patterns of positioning and movement of plastids was performed by light microscopy. The results obtained led us to detail a mode of gravity sensing by roots in which the interactions between moving amyloplasts, cytoplasm and cytoskeleton were discussed.