Nereocystis luetkeana is a canopy‐forming kelp that exhibits morphological plasticity across hydrodynamic gradients, producing broad, undulate blades in slow flow and narrow, flattened blades in fast flow, enabling thalli to reduce drag while optimizing photosynthesis. While the functional significance of this phenomenon has been well studied, the developmental and physiological mechanisms that facilitate the plasticity remain poorly understood. In this study, we conducted three experiments to characterize how the (1) magnitude, (2) direction, and (3) location of plasticity‐inducing mechanical stimuli affect the morphology of Nereocystis blades. We found that applying a gradient of tensile force caused blades to grow progressively longer, narrower, less ruffled, and heavier in a linear fashion, suggesting that Nereocystis is equally well adapted for all conditions within its hydrodynamic niche. We also found that applying tension transversely across blades caused the growth response to rotate 90°, indicating that there is no substantial separation between the sites of stimulus perception and response and suggesting that a long‐distance signaling mechanism, such as a hormone, is unlikely to mediate this phenomenon. Meristoderm cells showed morphological changes that paralleled those of their respective blades in this experiment, implying that tissue‐level morphology is influenced by cell growth. Finally, we found that plasticity was only induced when tension was applied directly to the growing tissue, reinforcing that long‐distance signaling is probably not involved and possibly indicating that the mechanism on display generally requires an intercalary meristem to facilitate mechanoperception.

中文翻译：

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海带Nereocystis luetkeana（Phaeophyceae）的形态可塑性对机械负荷的大小，方向和位置敏感。

Nereocystis luetkeana是形成冠层的海带，在水动力梯度中表现出形态可塑性，在缓慢流动时产生宽阔起伏的叶片，在快速流动时产生窄而扁平的叶片，使拟南芥能够在优化光合作用的同时减少阻力。虽然已经很好地研究了这种现象的功能重要性，但促进可塑性的发育和生理机制仍然知之甚少。在这项研究中，我们进行了三个实验，以表征（1）大小，（2）方向和（3）可塑性诱导机械刺激的位置如何影响神经囊肿的形态刀片。我们发现，施加拉力梯度会导致叶片以线性方式逐渐变长，变窄，起皱和加重，这表明神经囊肿同样可以很好地适应其流体力学领域内的所有条件。我们还发现，在叶片上横向施加张力会导致生长响应旋转90°，这表明刺激感知和响应位点之间没有实质性的分离，这表明长距离信号传导机制（例如激素）不太可能调解这种现象。在此实验中，Meristoderm细胞显示出与其各自叶片相似的形态变化，这表明组织水平形态受到细胞生长的影响。最后，我们发现，仅当将张力直接施加到生长中的组织时，才产生可塑性。