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Influence of microgravity on ultrastructure and storage reserves in seeds of Brassica rapa LSuccessful plant reproduction under spaceflight conditions has been problematic in the past. During a 122 d opportunity on the Mir space station, full life cycles of Brassica rapa L. were completed in microgravity in a series of three experiments in the Svet greenhouse. Ultrastructural and cytochemical analyses of storage reserves in mature dry seeds produced in these experiments were compared with those of seeds produced during a high-fidelity ground control. Additional analyses were performed on developing Brassica embryos, 15 d post pollination, which were produced during a separate experiment on the Shuttle (STS-87). Seeds produced on Mir had less than 20% of the cotyledon cell number found in seeds harvested from the ground control. Cytochemical localization of storage reserves in mature cotyledons showed that starch was retained in the spaceflight material, whereas protein and lipid were the primary storage reserves in ground control seeds. Protein bodies in mature cotyledons produced in space were 44% smaller than those in the ground control seeds. Fifteen days after pollination, cotyledon cells from mature embryos formed in space had large numbers of starch grains, and protein bodies were absent, while in developing ground control seeds at the same stage, protein bodies had already formed and fewer starch grains were evident. These data suggest that both the late stage of seed development and maturation are changed in Brassica by growth in a microgravity environment. While 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
20040088883
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Kuang, A.
(The University of Texas-Pan American Edinburg 78539, United States)
Xiao, Y.
McClure, G.
Musgrave, M. E.
Date Acquired
August 21, 2013
Publication Date
June 1, 2000
Publication Information
Publication: Annals of botany
Volume: 85
Issue: 6
ISSN: 0305-7364
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAG2-1020
CONTRACT_GRANT: NAG2-1375
CONTRACT_GRANT: NAG1-00139
Distribution Limits
Public
Copyright
Other
Keywords
NASA Experiment Number 9600004
Flight Experiment
long duration
NASA Discipline Plant Biology
manned
Non-NASA Center
STS-87 Shuttle Project
NASA Experiment Number 9401653
short duration
Mir Project

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