Vigorous synthesis of indole-3-acetic acid in the apical very tip leads to a constant basipetal flow of the hormone in maize coleoptiles
Vigorous synthesis of indole-3-acetic acid in the apical very tip leads to a constant basipetal flow of the hormone in maize coleoptiles
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DOI：
10.1016/j.plantsci.2004.09.010
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发表时间：
2005-02-01
期刊：
影响因子：
5.2
通讯作者：
Koshiba, T
中科院分区：
文献类型：
--
作者：
Mori, Y;Nishimura, T;Koshiba, T
胚芽鞘尖端最有可能是生长素（吲哚-3-乙酸（IAA））生物合成位点的候选者。我们使用气相色谱-质谱法快速、微量测定 IAA，详细研究了玉米 (Zea mays L.) 胚芽鞘中游离和共轭 IAA 的分布和运动。 IAA 的最高浓度（约 250 ng/g 鲜重）出现在距顶端 0-0.5 nm 的范围内。这些量急剧下降，直到距离顶部 2 毫米，然后逐渐远离顶部逐渐下降，在基底区域达到约 13 ng/g 鲜重。约 500 pg/h 的 IAA 从 2-3 圈尖端部分扩散到琼脂块中。在 3.5 小时孵育期间积累的可扩散 IAA 量比孵育前在 2 mm 吸头中检测到的游离 IAA 高出 6 倍多。在孵育过程中，虽然吸头中的游离IAA略有减少，但结合的IAA的量却有所增加。用 N-1-萘基邻苯二甲酸（一种生长素转运抑制剂）处理会导致大量游离 IAA 积聚在 2 毫米尖端中。这些结果提供了明确的证据，表明玉米胚芽鞘顶端0-2毫米区域具有从头产生IAA的潜力，这导致IAA持续流向下部。 (C) 2004 年，爱思唯尔爱尔兰有限公司出版。
Coleoptile tips are the most likely candidates for the site of auxin (indole-3-acetic acid (IAA)) biosynthesis. Using a rapid, micro-scale method for IAA determination by gas chromatography-mass spectrometry, we investigated in detail the distribution and movement of free and conjugated IAA in maize (Zea mays L.) coleoptiles. The highest concentrations of IAA (approximately 250 ng/g fresh weight) were found within 0-0.5 nun of the apical tip. These amounts decreased steeply until 2 mm from the top and then gently decreased further away from the top, reaching about 13 ng/g fresh weight in the basal region. About 500 pg/h of IAA diffused from 2-3 turn tip sections into an agar block. This amount of diffusible IAA that accumulated during the 3.5 h incubation, was more than 6 times higher than that of free IAA detected in the 2 mm tip before incubation. During the incubation, while the free IAA in the tip decreased slightly, the amount of conjugated IAA rather increased. Treatment with N-1-naphthylphthalamic acid, an auxin transport inhibitor, caused a large amount of free IAA to accumulate in the 2 mm tip. These results provide definite evidence that the apical 0-2 mm region of maize coleoptiles has the potential to produce IAA de novo, which leads to a constant flow of IAA towards the lower parts. (C) 2004 Published by Elsevier Ireland Ltd.