Shoot-derived auxin is essential for early lateral root emergence in Arabidopsis seedlings
Shoot-derived auxin is essential for early lateral root emergence in Arabidopsis seedlings
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DOI：
10.1046/j.0960-7412.2001.01217.x
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发表时间：
2002-02-01
期刊：
影响因子：
7.2
通讯作者：
Sandberg, G
中科院分区：
文献类型：
--
作者：
Bhalerao, RP;Eklöf, J;Sandberg, G
侧根的形成深受生长素的影响。在这里，我们提出的数据表明，光影响萌发中的拟南芥幼苗中吲哚-3-乙酸（IAA）的形成。IAA从发育中的叶片转运到根系，在根系中以短时间脉冲的形式被检测到，这是幼苗发育早期侧根原基（LRP）出现所必需的。在根部检测到IAA脉冲之前，去除根尖组织可以抑制LRP的发生，但这种处理对LRP的发生影响很小。我们的研究结果确定，第一个发育的真叶是LRP第一次出现所需的IAA最可能的来源，因为与去除叶片相比，去除子叶对LRP的出现只有很小的影响。相对于LRP的萌发，基部IAA浓度梯度和根尖高浓度IAA似乎控制了LRP的萌发。在萌发后10天，根系合成IAA的能力显著增加，这反过来反映在这一阶段侧根出苗对空气组织来源的生长素的依赖性降低。我们提出了一个在幼苗发育早期侧根形成的模型，该模型可分为两个阶段：(i)依赖于根尖定位的IAA源的LRP起始阶段；（ii）萌发后10天依赖于叶片来源的IAA的LRP出苗期。
Lateral root formation is profoundly affected by auxins. Here we present data which indicate that light influences the formation of indole-3-acetic acid (IAA) in germinating Arabidopsis seedlings. IAA transported from the developing leaves to the root system is detectable as a short-lived pulse in the roots and is required for the emergence of the lateral root primordia (LRP) during early seedling development. LRP emergence is inhibited by the removal of apical tissues prior to detection of the IAA pulse in the root, but this treatment has minimal effects on LRP initiation. Our results identify the first developing true leaves as the most likely source for the IAA required for the first emergence of the LRP, as removal of cotyledons has only a minor effect on LRP emergence in contrast to removal of the leaves. A basipetal IAA concentration gradient with high levels of IAA in the root tip appears to control LRP initiation, in contrast to their emergence. A significant increase in the ability of the root system to synthesize IAA is observed 10 days after germination, and this in turn is reflected in the reduced dependence of the lateral root emergence on aerial tissue-derived auxin at this stage. We propose a model for lateral root formation during early seedling development that can be divided into two phases: (i) an LRP initiation phase dependent on a root tip-localized IAA source, and (ii) an LRP emergence phase dependent on leaf-derived IAA up to 10 days after germination.