The roles of ethylene, auxin, abscisic acid, and gibberellin in the hyponastic growth of submerged Rumex palustris petioles
The roles of ethylene, auxin, abscisic acid, and gibberellin in the hyponastic growth of submerged Rumex palustris petioles
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DOI：
10.1104/pp.104.049197
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发表时间：
2004-10-01
期刊：
影响因子：
7.4
通讯作者：
Voesenek, LACJ
中科院分区：
文献类型：
--
作者：
Cox, MCH;Benschop, JJ;Voesenek, LACJ
芦笋对完全淹没的反应是年轻叶柄向上运动。这种所谓的低空反应，结合刺激叶柄伸长，使叶片露出水面，恢复与大气的接触。我们对这种差异生长过程进行了详细的研究，涵盖了已知信号转导途径的完整范围：从差异生长的细胞定位到激素调节，以及细胞壁松动蛋白（扩张蛋白）作为下游靶标的可能参与。我们发现，下凹生长是由叶柄基部的细胞伸长差异引起的，背面（下）表面的细胞比正面（上）表面的细胞伸长得快。药理学研究和内源性激素测量表明，乙烯、生长素、脱落酸（ABA）和赤霉素调节不同的、有时重叠的低生长阶段。乙烯、外源ABA和生长素共同调控下胚轴生长的启动和最大叶柄角的维持，而乙烯、外源ABA和赤霉素则影响反应的速度。我们发现，浸泡诱导的叶柄基部内源性吲哚-3-乙酸的差异再分配可能在维持反应中起作用，但在低生长的开始中没有作用。由于淹没不会诱导扩张蛋白在叶柄基部的差异表达，因此这种细胞壁松动蛋白不太可能是调节差异细胞伸长的激素的下游目标，这些激素导致了水淹诱导的河鼠低生长。
Rumex palustris responds to complete submergence with upward movement of the younger petioles. This so-called hyponastic response, in combination with stimulated petiole elongation, brings the leaf blade above the water surface and restores contact with the atmosphere. We made a detailed study of this differential growth process, encompassing the complete range of the known signal transduction pathway: from the cellular localization of differential growth, to the hormonal regulation, and the possible involvement of a cell wall loosening protein (expansin) as a downstream target. We show that hyponastic growth is caused by differential cell elongation across the petiole base, with cells on the abaxial (lower) surface elongating faster than cells on the adaxial (upper) surface. Pharmacological studies and endogenous hormone measurements revealed that ethylene, auxin, abscisic acid (ABA), and gibberellin regulate different and sometimes overlapping stages of hyponastic growth. Initiation of hyponastic growth and (maintenance of) the maximum petiole angle are regulated by ethylene, ABA, and auxin, whereas the speed of the response is influenced by ethylene, ABA, and gibberellin. We found that a submergence-induced differential redistribution of endogenous indole-3-acetic acid in the petiole base could play a role in maintenance of the response, but not in the onset of hyponastic growth. Since submergence does not induce a differential expression of expansins across the petiole base, it is unlikely that this cell wall loosening protein is the downstream target for the hormones that regulate the differential cell elongation leading to submergence-induced hyponastic growth in R. palustris.