8.トウモロコシ幼葉鞘先端で合成されるIAAの輸送機構の解析(口頭発表)

概要

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Indole-3-acetic acid (IAA) is an important hormone in almost all aspects of plant growth and development. From our previous work using maize coleoptiles, it has been indicated that the tip region of coleoptiles is the site of IAA biosynthesis from tryptophan (Trp) and the IAA synthesized in the tips is transported to the lower regions. However these studies were performed with sectioned maize coleoptiles. In the present study, we tried to investigate the movement of synthesized IAA at the tip in intact coleoptiles. The results showed the high efficient incorporation of stable isotope label from [^^<13>C_<11>^^<15>N_2]-Trp into IAA molecules during 15 to 30 min feeding. The rate of labeled IAA was about up to 15% of endogenous free IAA. The labeled IAA did not stay at the tip region but immediately transported to the lower parts at the rate of approximately 7 mm/hr. These results suggest that IAA continuously synthesized from Trp at the tip region is transported to the lower region in a polar transport manner. Even the different concentration of [^^<13>C_<11>^^<15>N_2]-Trp was used for the feeding to the tip, the total amount of free IAA in the coleoptile was not changed. These results suggest that this system is reflected in vivo IAA biosynthetic situations.
植物化学調節学会の論文
2007-10-05