Plant Biodynamics Laboratory, Institute Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands.
J Exp Bot. 2012 Jun;63(11):4213-8. doi: 10.1093/jxb/ers106. Epub 2012 Apr 2.
In higher plants, cell-to-cell polar auxin transport (PAT) of the phytohormone auxin, indole-3-acetic acid (IAA), generates maxima and minima that direct growth and development. Although IAA is present in all plant phyla, PAT has only been detected in land plants, the earliest being the Bryophytes. Charophyta, a group of freshwater green algae, are among the first multicellular algae with a land plant-like phenotype and are ancestors to land plants. IAA has been detected in members of Charophyta, but its developmental role and the occurrence of PAT are unknown. We show that naphthylphthalamic acid (NPA)-sensitive PAT occurs in internodal cells of Chara corallina. The relatively high velocity (at least 4-5 cm/h) of auxin transport through the giant (3-5 cm) Chara cells does not occur by simple diffusion and is not sensitive to a specific cytoplasmic streaming inhibitor. The results demonstrate that PAT evolved early in multicellular plant life. The giant Chara cells provide a unique new model system to study PAT, as Chara allows the combining of real-time measurements and mathematical modelling with molecular, developmental, cellular, and electrophysiological studies.
在高等植物中，细胞间的生长素极性运输（PAT）将植物激素吲哚乙酸（IAA）运输到生长素浓度的最大值和最小值处，从而指导生长和发育。尽管 IAA 存在于所有植物门中，但 PAT 仅在陆地植物中被检测到，最早的是苔藓植物。Charophyta 是一组淡水绿藻，是具有陆地植物表型的最早的多细胞藻类之一，也是陆地植物的祖先。已经在 Charophyta 的成员中检测到了 IAA，但它的发育作用和 PAT 的发生情况尚不清楚。我们表明，萘基邻氨甲酰苯甲酸（NPA）敏感的 PAT 发生在珊瑚藻的节间细胞中。通过 3-5 厘米的巨大珊瑚藻细胞的生长素运输速度相对较高（至少 4-5 厘米/小时），这不是通过简单的扩散发生的，并且对特定的细胞质流动抑制剂不敏感。这些结果表明 PAT 在多细胞植物生命的早期就已经进化了。巨大的珊瑚藻细胞提供了一个独特的新模型系统来研究 PAT，因为珊瑚藻允许将实时测量和数学建模与分子、发育、细胞和电生理学研究结合起来。
