CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China.
AMAP (Botanique et Modélisation de l'Architecture des Plantes et des Végétations), Université de Montpellier, CIRAD, CNRS, INRAE, IRD, 34000 Montpellier, France.
J Exp Bot. 2024 May 20;75(10):2951-2964. doi: 10.1093/jxb/erae083.
Vessel traits contribute to plant water transport from roots to leaves and thereby influence how plants respond to soil water availability, but the sources of variation in fine root anatomical traits remain poorly understood. Here, we explore the variations of fine root vessel traits along topological orders within and across tropical tree species. Anatomical traits were measured along five root topological orders in 80 individual trees of 20 species from a tropical forest in southwestern China. We found large variations for most root anatomical traits across topological orders, and strong co-variations between vessel traits. Within species, theoretical specific xylem hydraulic conductivity (Kth) increased with topological order due to increased mean vessel diameter, size heterogeneity, and decreased vessel density. Across species, Kth was associated with vessel fraction in low-order roots and correlated with mean vessel diameter and vessel density in high-order roots, suggesting a shift in relative anatomical contributors to Kth from the second- to fifth-order roots. We found no clear relationship between Kth and stele: root diameter ratios. Our study shows strong variations in root vessel traits across topological orders and species, and highlights shifts in the anatomical underpinnings by varying vessel-related anatomical structures for an optimized water supply.
导管特性有助于植物将水分从根部输送到叶片，并影响植物对土壤水分供应的响应，但导管的细微结构特性的变异来源仍知之甚少。在这里，我们探索了热带树种内和跨树种的根拓扑序中细根导管特性的变化。在中国西南部的一个热带森林中，我们在 80 株 20 个树种的个体树木中沿着五个根拓扑序测量了解剖学特性。我们发现大多数根解剖特性在拓扑序之间存在很大的变化，并且导管特性之间存在强烈的协变关系。在种内，由于平均导管直径、大小异质性和导管密度的增加，理论上的木质部比导率（Kth）随着拓扑序的增加而增加。在种间，Kth 与低序根中的导管分数有关，与高序根中的平均导管直径和导管密度相关，这表明相对解剖学对 Kth 的贡献从第二到第五序根发生了转变。我们没有发现 Kth 与木质部:根直径比之间有明显的关系。我们的研究表明，根导管特性在拓扑序和种间存在强烈的变化，并强调了通过改变与导管相关的解剖结构来优化供水的情况下，解剖基础的变化。
