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標題: 光照抑制大豆幼苗伸長特性之研究
The Characterization of Light-inhibited Elongation in Soybean Seedlings
作者: 任遵命
Tsun-Min Jen Tong
關鍵字: Soybean Seedlings;大豆幼苗;Light-inhibited;光照抑制
Project: Horticulture NCHU, Volume 3, Page(s) 42-43.
興大園藝, Volume 3, Page(s) 42-43.
Light-inhibited soybean (Glycine max L. cv. Wayne) hypocotyl elongation was studied in intact seedlings and excised segments. These observations were made:
(1) Light-inhibited elongation was readily observed in intact seedlings, especially when dark-grown seedlings with hypocotyl about 6 cm or longer were transferred to light. It was observed that the elongating region of these intact seedlings was quite sensitive to photoinhibition. However, inhibition of elongation by light was not readily observed in excised segments.
(2) Unexpectedly, it was found that excised segments, 0.5-1.5 cm from cotyledons, could be inhibited by light, if they were incubated for more than 8 hr. Experiments indicated that there was regeneration of a center of auxin-producing cells in these excised segments. The photoinhibition of hypocotyl elongation of excised segments was not observed in auxin-treated segments. The lack of photoinhibition of elongation seen in the 8 hr (or shorter) experiments was consistent with results obtained using a continuous growth measurement apparatus.
(3) Contrary to the experiments with excised elongating segments, in studies of excised elongating segments with various tissue attached (hook, plumule or cotyledons), photoinhibition of elongation clearly occurred. The kinetics of this inhibition were characterized using the continuous growth apparatus.
(4) It was found that wavelengths in the blue were most active in light-inhibited elongation. Contrary to previous results, red wave bands were inactive, even when the hook, cotyledons and plumule were left attached to the elongating segment.
(5) Long-term and short-term experiments which utilized segments alone and segments with various apical tissues attached, showed that the light-receiving cells were located in the hooks. It was also shown that cells in the hook were the source of endogenous auxin. Since the photoinhibiton of hypocotyl elongation of segments with various tissues attached could be reversed by auxin both in long-term and short-term experiments, it was concluded that the photoinhibition of cells to the elongating region was mediated by the auxin-supplying cells of the tip or by auxin-transporting cells. Auxin transport was studied; there was no effect of light on auxin transport. Therefore, it seems quite likely that light somehow decreases auxin export by auxin-producing cells.
(6) These experiments support van Overbeek's 1936 auxin hypothesis, thought to be incorrect since 1941.
University of Illinois at Urbana-Champaign 1977
ISSN: 0255-5921
Appears in Collections:第03期

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