Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, China.
College of Forestry, Northwest A&F University, Yangling, Shaanxi, China.
Tree Physiol. 2019 Jun 1;39(6):1019-1031. doi: 10.1093/treephys/tpz015.
Hydraulic safety and efficiency have become the central concept of the interpretation of the structure and function of vessels and their interconnections. Plants form an appropriate xylem network structure to maintain a balance of hydraulic safety vs efficiency. The term 'tracheid bridge' is used to describe a possible pathway of water transport between neighboring vessels via tracheids, and this pathway could also provide increased safety against embolisms. However, the only physiological study of such a structure thus far has been in Hippophae rhamnoides Linn. To test the function of tracheid bridges, this research examined four species that have relatively long and solitary vessels, which are two of the criteria for efficient tracheid bridges. Tracheids contributed less than 2.2% of the total conductance of the vessels in these species, but in theory, tracheids could serve as very efficient transport connector pathways that may or may not make direct vessel-to-vessel contact via pit fields between adjacent vessels. In some species, tracheid bridges may represent the dominant pathway for water flow between vessels, whereas in other species, tracheid bridges may be sub-dominant or virtually nil. Broader searches of woody taxa are needed to reveal the functional importance of tracheid bridges in vascular plants.
水力安全和效率已成为解释船舶及其连接结构和功能的核心概念。植物形成适当的木质部网络结构，以维持水力安全与效率之间的平衡。“导管桥”一词用于描述通过导管在相邻容器之间进行水运输的可能途径，该途径还可以提高对栓塞的安全性。然而，迄今为止，对这种结构的唯一生理学研究是在沙棘属植物中进行的。为了测试导管桥的功能，本研究检验了四个具有相对较长和孤立导管的物种，这是高效导管桥的两个标准。导管在这些物种的导管总导纳中仅贡献了不到 2.2％，但从理论上讲，导管可以作为非常有效的运输连接途径，可能通过相邻导管之间的纹孔场直接与导管接触，也可能不接触。在某些物种中，导管桥可能代表了导管之间水流的主要途径，而在其他物种中，导管桥可能处于次要地位或几乎不存在。需要对木本类群进行更广泛的搜索，以揭示导管桥在维管植物中的功能重要性。
