Silva Luciano M, Pereira Luciano, Kaack Lucian, Guan Xinyi, Pfaff Jonas, Trabi Christophe L, Jansen Steven
Institute of Botany, Ulm University, Ulm, Germany.
Botanical Garden of Ulm University, Hans-Krebs-Weg, Ulm, Germany.
Plant Cell Environ. 2024 Dec;47(12):4977-4991. doi: 10.1111/pce.15084. Epub 2024 Aug 9.
Understanding xylem embolism formation is challenging due to dynamic changes and multiphase interactions in conduits. Here, we hypothesise that embolism spread involves gas diffusion in xylem, and is affected by time. We measured hydraulic conductivity (K) in flow-centrifuge experiments over 1 h at a given pressure and temperature for stem samples of three angiosperm species. Temporal changes in K at 5, 22, and 35°C, and at various pressures were compared to modelled gas concentration changes in a recently embolised vessel in the centre of a centrifuge sample. Temporal changes in K were logarithmic and species-specific. Maximum relative increases of K between 6% and 40% happened at 22°C for low centrifugal speed (<3250 RPM), while maximum decreases between 41% and 61% occurred at higher speeds. These reductions in K were experimentally shown to be associated with a temporal increase of embolism at the centre of centrifuge samples, which was likely associated with gas concentration increases in recently embolized vessels. Although embolism is mostly pressure-driven, our experimental and modelled data indicate that time, conduit characteristics, and temperature are involved due to their potential role in gas diffusion. Gas diffusion, however, does not seem to cover the entire process of embolism spread.
由于导管中的动态变化和多相相互作用，理解木质部栓塞形成具有挑战性。在这里，我们假设栓塞扩散涉及木质部中的气体扩散，并受时间影响。我们在给定压力和温度下，对三种被子植物茎样本进行了1小时的流动离心实验，测量了水力传导率（K）。将5℃、22℃和35℃以及不同压力下K的时间变化与离心样本中心最近栓塞的导管中模拟的气体浓度变化进行了比较。K的时间变化呈对数关系且具有物种特异性。在22℃下，低离心速度（<3250转/分钟）时K的最大相对增加在6%至40%之间，而在较高速度下，最大减少在41%至61%之间。实验表明，K的这些降低与离心样本中心栓塞的时间增加有关，这可能与最近栓塞的导管中气体浓度增加有关。尽管栓塞主要由压力驱动，但我们的实验和模拟数据表明，由于时间、导管特性和温度在气体扩散中的潜在作用，它们也参与其中。然而，气体扩散似乎并未涵盖栓塞扩散的整个过程。
