著者

保尊 隆享 若林 和幸 曽我 康一

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.17, no.2, pp.135-143, 2003 (Released:2006-01-31)

参考文献数

31

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The involvement of anti-gravitational polysaccharides in gravity resistance, one of two major gravity responses in plants, was discussed. In dicotyledons, xyloglucans are the only cell wall polysaccharides, whose level, molecular size, and metabolic turnover were modified under both hypergravity and microgravity conditions, suggesting that xyloglucans act as anti-gravitational polysaccharides. In monocotyledonous Poaceae, (1→3),(1→4)-b-glucans, instead of xyloglucans, were shown to play a role as anti-gravitational polysaccharides. These polysaccharides are also involved in plant responses to other environmental factors, such as light and temperature, and to some phytohormones, such as auxin and ethylene. Thus, the type of anti-gravitational polysaccharides is different between dicotyledons and Poaceae, but such polysaccharides are universally involved in plant responses to environmental and hormonal signals. In gravity resistance, the gravity signal may be received by the plasma membrane mechanoreceptors, transformed and transduced within each cell, and then may modify the processes of synthesis and secretion of the anti-gravitational polysaccharides and the cell wall enzymes responsible for their degradation, as well as the apoplastic pH, leading to the cell wall reinforcement. A series of events inducing gravity resistance are quite independent of those leading to gravitropism.

著者

保尊 隆享

出版者

特定非営利活動法人 日本バイオレオロジー学会

雑誌

日本バイオレオロジー学会誌 (ISSN:09134778)

巻号頁・発行日

vol.17, no.3, pp.6-10, 2003-09-30 (Released:2012-09-24)

参考文献数

11

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The plant cell wall is believed to play an important role in resisting gravity force and supporting the plant body under 1 g on earth, as the bones and muscles in an animal body. However, no direct evidence supporting this idea has been provided by space experiments. We analyzed the cell wall properties of rice coleoptiles and Arabidopsis hypocotyls grown under microgravity conditions during the Space Shuttle STS-95 mission. In space, elongation growth of both organs was stimulated and the cell wall extensibility increased. The increase in the wall extensibility in space was almost completely attributable to the increase in the irreversible extensibility. Also, the levels and the molecular size of the certain matrix polysaccharides, such as (1→3), (1→4)-β - glucans in rice coleoptiles and xyloglucans in Arabidopsis hypocotyls, decreased in space. These modifications in the matrix polysaccharides could be involved in increasing the cell wall extensibility, leading to growth stimulation in space. The results suggest that plant seedlings modify the metabolism of the certain cell wall polysaccharides and thus regulate the cell wall extensibility and the growth rate, thereby adapting different gravity conditions.

著者

保尊 隆享

出版者

一般社団法人 植物化学調節学会

雑誌

植物の化学調節 (ISSN:03889130)

巻号頁・発行日

vol.34, no.2, pp.226-235, 1999-12-25 (Released:2018-03-15)

参考文献数

81

被引用文献数

2