Analysis of circular bordered pit function - II. Gymnosperm tracheids with torus-margo pit membranes
Analysis of circular bordered pit function - II. Gymnosperm tracheids with torus-margo pit membranes
复制标题
DOI：
10.3732/ajb.91.3.386
复制
发表时间：
2004-03-01
影响因子：
3
通讯作者：
Pittermann, J
中科院分区：
文献类型：
--
作者：
Hacke, UG;Sperry, JS;Pittermann, J
一个木质部导管功能的模型被应用于裸子植物管胞与被子植物导管的比较与环面边缘纹孔膜。对17种具有圆形纹孔的裸子植物的管胞进行了分析，气种压力为0.8 ~ 11.8MPa。管胞比血管更能抵抗内爆，这与它们在运输和支持方面的双重功能一致。管胞坑是3.3至44倍，因为更大的膜电导率的环面边缘配置的导水率比容器坑。环面和凹坑尺寸之间的紧密缩放最大化了凹坑导电性。较高的纹孔电导率允许管胞比导管短1.7-3.4倍，并且仍然达到其管腔限制的最大电导率的95%。预测的管胞长度与实测长度一致。环面-边缘结构对于最大化固有长度受限的管胞的导电性是重要的：用导管膜代替环面-边缘膜导致茎管胞导电性下降41%。管胞的水力效率不低于船只，如果他们足够长，以达到其管腔限制电导率。然而，这仅可能用于低于约60-70 μ m的管腔直径。
A model of xylem conduit function was applied to gymnosperm tracheids with torus-margo pit membranes for comparison with angiosperm vessels. Tracheids from 17 gymnosperm tree species with circular bordered pits and air-seed pressures from 0.8 to 11.8 MPa were analyzed. Tracheids were more reinforced against implosion than vessels, consistent with their double function in transport and support. Tracheid pits were 3.3 to 44 times higher in hydraulic conductivity than vessel pits because of greater membrane conductivity of the torus-margo configuration. Tight scaling between torus and pit size maximized pit conductivity. Higher pit conductivity allowed tracheids to be 1.7-3.4 times shorter than vessels and still achieve 95% of their lumen-limited maximum conductivity. Predicted tracheid lengths were consistent with measured lengths. The torus-margo structure is important for maximizing the conductivity of the inherently length-limited tracheid: replacing the torus-margo membrane with a vessel membrane caused stem tracheid conductivity to drop by 41%. Tracheids were no less hydraulically efficient than vessels if they were long enough to reach their lumen-limiting conductivity. However, this may only be possible for lumen diameters below approximately 60-70 mum.