Botanisches Institut, Universität zu Köln, Gyrhofstr. 15, D-50931 Köln, Germany.
Mol Plant. 2008 Mar;1(2):359-67. doi: 10.1093/mp/ssm027. Epub 2008 Feb 8.
Besides providing protection against mechanical damage to the root tip, the root cap is involved in the perception and processing of diverse external and internal stimuli resulting in altered growth and development. The transduction of these stimuli includes hormonal signaling pathways such as those of auxin, ethylene and cytokinin. Here, we show that the root cap is essential for the ethylene-induced regulation of elongation growth and root hair formation in maize. Exogenously applied ethylene is no longer able to inhibit elongation growth when the root cap has been surgically removed prior to hormone treatment. Reconstitution of the cap positively correlates with the developing capacity of the roots to respond to ethylene again. In contrast, the removal of the root cap does not per se affect growth inhibition controlled by auxin and cytokinin. Furthermore, our semi-quantitative RT-PCR results support earlier findings that the maize root cap is a site of high gene expression activity with respect to sensing and responding to hormones such as ethylene. From these data, we propose a novel function of the root cap which is the establishment of competence to respond to ethylene in the distal zones of the root.
除了为根尖提供机械损伤保护外，根冠还参与了多种外部和内部刺激的感知和处理，从而导致生长和发育的改变。这些刺激的转导包括激素信号通路，如生长素、乙烯和细胞分裂素。在这里，我们表明根冠对于玉米中乙烯诱导的伸长生长和根毛形成的调节是必不可少的。在激素处理前通过手术切除根冠，外源施加的乙烯不再能够抑制伸长生长。根冠的重建与根再次响应乙烯的发育能力呈正相关。相比之下，根冠的去除本身并不影响生长素和细胞分裂素控制的生长抑制。此外，我们的半定量 RT-PCR 结果支持了早期的发现，即玉米根冠是一个具有高基因表达活性的部位，能够感知和响应激素，如乙烯。根据这些数据，我们提出了根冠的一个新功能，即建立对根远端区域乙烯的反应能力。
