四个北方硬木树种中跨生长轮导管连接的功能意义。
The functional implications of tracheary connections across growth rings in four northern hardwood trees.
机构信息
School of Forest Resources, University of Maine, Orono, ME, USA.
School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA.
出版信息
Ann Bot. 2019 Sep 24;124(2):297-306. doi: 10.1093/aob/mcz076.
BACKGROUND AND AIMS
Deciduous angiosperm trees transport xylem sap through trunks and branches in vessels within annual growth rings. Utilizing previous growth rings for sap transport could increase vessel network size and redundancy but may expose new xylem to residual air embolisms in the network. Despite the important role of vessel networks in sap transport and drought resistance, our understanding of cross-ring connections within and between species is limited.
METHODS
We studied cross-ring connections in four temperate deciduous trees using dye staining and X-ray microcomputed tomography (microCT) to detect xylem connectivity across growth rings and quantify their impact on hydraulic conductivity.
KEY RESULTS
Acer rubrum and Fraxinus americana had cross-ring connections visible in microCT but only A. rubrum used previous growth rings for axial sap flow. Fagus grandifolia and Quercus rubra, however, did not have cross-ring connections. Accounting for the number of growth rings that function for axial transport improved hydraulic conductivity estimates.
CONCLUSIONS
These data suggest that the presence of cross-ring connections may help explain aspects of whole-tree xylem sap transport and should be considered for plant hydraulics measurements in these species and others with similar anatomy.
背景与目的
落叶被子植物通过树干和树枝中的导管在年度生长环内输送木质部汁液。利用以前的生长环进行汁液运输可以增加导管网络的大小和冗余度，但可能会使新的木质部暴露在网络中的残余空气栓塞中。尽管导管网络在汁液运输和抗旱性方面起着重要作用，但我们对物种内和物种间的跨生长环连接的理解有限。
方法
我们使用染色和 X 射线微计算机断层扫描（microCT）研究了四种温带落叶树的跨生长环连接，以检测跨生长环的木质部连通性，并量化其对水力传导性的影响。
主要结果
Acer rubrum 和 Fraxinus americana 在 microCT 中可见跨生长环连接，但只有 Acer rubrum 将以前的生长环用于轴向汁液流动。然而，Fagus grandifolia 和 Quercus rubra 没有跨生长环连接。考虑到用于轴向运输的生长环数量，可以提高水力传导性估计值。
结论
这些数据表明，跨生长环连接的存在可能有助于解释整树木质部汁液运输的某些方面，并且应该在这些具有类似解剖结构的物种和其他物种的植物水力学测量中考虑到这一点。
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