Asymmetric distribution of auxin correlates with gravitropism and phototropism but not with autostraightening (autotropism) in pea epicotyls
Asymmetric distribution of auxin correlates with gravitropism and phototropism but not with autostraightening (autotropism) in pea epicotyls
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DOI：
10.1093/jxb/erj069
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发表时间：
2006-03-01
影响因子：
6.9
通讯作者：
Iino, M
中科院分区：
文献类型：
--
作者：
Haga, K;Iino, M
研究了天然生长素吲哚-3-乙酸 (IAA) 的分布与红光豌豆 (Pisum sativum L.) 幼苗上胚轴向性之间的关系。使用从胚芽施加的 H-3-IAA 作为示踪剂，在第三节间的限定区域中进行分布测量。研究的向光性是向地性、脉冲诱导的向光性和时间依赖性向光性。研究扩展到了向重力曲率之后的自直（自向性）阶段。研究发现，在向地性和向光性曲率的早期阶段，IAA 不对称地分布在该区域的两半之间，在凸侧出现较高的 IAA 水平。在表皮中发现了这种不对称性，除了一种情况（脉冲诱导的向光性）外，在整个组织中没有检测到不对称性。结论是，生长素不对称性介导向地性和向光性，并且表皮或外周细胞层在豌豆上胚轴中生长素不对称性的建立中发挥重要作用。在由于生长不对称性逆转而导致的自动矫直过程中，IAA 不对称性的程度有所降低，但其方向并未逆转。这一结果表明，自动矫直不是通过生长素分布来调节的。在这项研究中，还测量了研究区域两侧的生长情况。在某些情况下，测得的 IAA 分布无法充分解释当地增长率，需要进一步详细调查。
The relationships between the distribution of the native auxin indole-3-acetic acid (IAA) and tropisms in the epicotyl of red light-grown pea (Pisum sativum L.) seedlings have been investigated. The distribution measurement was made in a defined zone of the third internode, using H-3-IAA applied from the plumule as a tracer. The tropisms investigated were gravitropism, pulse-induced phototropism, and time-dependent phototropism. The investigation was extended to the phase of autostraightening (autotropism) that followed gravitropic curvature. It was found that IAA is asymmetrically distributed between the two halves of the zone, with a greater IAA level occurring on the convex side, at early stages of gravitropic and phototropic curvatures. This asymmetry was found in epidermal peels and, except for one case (pulse-induced phototropism), no asymmetry was detected in whole tissues. It was concluded, in support of earlier results, that auxin asymmetry mediates gravitropism and phototropism and that the epidermis or peripheral cell layers play an important role in the establishment of auxin asymmetry in pea epicotyls. During autostraightening, which results from a reversal of growth asymmetry, the extent of IAA asymmetry was reduced, but its direction was not reversed. This result demonstrated that autostraightening is not regulated through auxin distribution. In this study, the growth on either side of the investigated zone was also measured. In some cases, the measured IAA distribution could not adequately explain the local growth rate, necessitating further detailed investigation.