Konrad W, Roth-Nebelsick A
Institut für Geowissenschaften, University of Tübingen, Sigwartstrasse 10, D-72076 Tübingen, Germany.
J Biol Phys. 2005 Jan;31(1):57-71. doi: 10.1007/s10867-005-6094-0.
During plant water transport, the water in the conducting tissue (xylem) is under tension. The system is then in a metastable state and prone to bubble development and subsequent embolism blocking further water transport. It has recently been demonstrated, that embolism can be repaired under tension (= novel refilling). A model (Pit Valve Mechanism = PVM) has also been suggested which is based on the development of a special meniscus in the pores (pits) between adjacent conduits. This meniscus is expected to be able to isolate embolized conduits from neighbouring conduits during embolism repair. In this contribution the stability of this isolating meniscus against perturbations is considered which inevitably occur in natural environments. It can be shown that pit shape affects the stability of PVM fundamentally in the case of perturbation. The results show that a concave pit shape significantly supports the stability of PVM. Concave pit shape should thus be of selective value for species practicing novel refilling.
在植物水分运输过程中，输导组织（木质部）中的水处于张力之下。此时系统处于亚稳态，容易形成气泡并随后发生栓塞，从而阻碍进一步的水分运输。最近有研究表明，栓塞可以在张力下修复（即新型再填充）。还提出了一个模型（纹孔阀机制 = PVM），该模型基于相邻导管之间孔隙（纹孔）中特殊弯月面的形成。预计这个弯月面能够在栓塞修复过程中将栓塞的导管与相邻导管隔离开来。在本论文中，考虑了这种隔离弯月面在自然环境中不可避免会出现的扰动下的稳定性。结果表明，在受到扰动的情况下，纹孔形状从根本上影响PVM的稳定性。结果显示，凹形纹孔形状显著支持PVM的稳定性。因此，凹形纹孔形状对于进行新型再填充的物种应具有选择价值。
