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Gravity independence of seed-to-seed cycling in Brassica rapaGrowth of higher plants in the microgravity environment of orbital platforms has been problematic. Plants typically developed more slowly in space and often failed at the reproductive phase. Short-duration experiments on the Space Shuttle showed that early stages in the reproductive process could occur normally in microgravity, so we sought a long-duration opportunity to test gravity's role throughout the complete life cycle. During a 122-d opportunity on the Mir space station, full life cycles were completed in microgravity with Brassica rapa L. in a series of three experiments in the Svet greenhouse. Plant material was preserved in space by chemical fixation, freezing, and drying, and then compared to material preserved in the same way during a high-fidelity ground control. At sampling times 13 d after planting, plants on Mir were the same size and had the same number of flower buds as ground control plants. Following hand-pollination of the flowers by the astronaut, siliques formed. In microgravity, siliques ripened basipetally and contained smaller seeds with less than 20% of the cotyledon cells found in the seeds harvested from the ground control. Cytochemical localization of storage reserves in the mature embryos showed that starch was retained in the spaceflight material, whereas protein and lipid were the primary storage reserves in the ground control seeds. While these successful seed-to-seed cycles show that gravity is not absolutely required for any step in the plant life cycle, seed quality in Brassica is compromised by development in microgravity.
Document ID
20040141614
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Musgrave, M. E.
(Louisiana State University Agricultural Center Baton Rouge 70803, United States)
Kuang, A.
Xiao, Y.
Stout, S. C.
Bingham, G. E.
Briarty, L. G.
Levenskikh, M. A.
Sychev, V. N.
Podolski, I. G.
Date Acquired
August 22, 2013
Publication Date
February 1, 2000
Publication Information
Publication: Planta
Volume: 210
Issue: 3
ISSN: 0032-0935
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Flight Experiment
NASA Discipline Plant Biology
Mir Project
Non-NASA Center
NASA Program Fundamental Space Biology
STS-84 Shuttle Project
short duration
long duration
manned
NASA Experiment Number 9401653

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