研究人员表明，木质部网络组织的增量变化与圆柱形的祖先形式不同，其通过减少液压故障的风险，导致逐步提高抗旱性。随着木质部链的复杂性增加，栓塞扩散的独立途径变得更少，并且越来越集中在更中心的导管中，从而限制了干旱期间栓塞的系统扩散。因此，干旱的选择可以解释化石记录中观察到的木质部的演化轨迹和现存形式的多样性。
据介绍，最早的维管束植物的茎有一个中央圆柱形的导水木质部，它迅速多样化为更复杂的形状。这种多样化被理解为与植物体大小和分枝的增加相吻合；然而，目前还没有发现有利于木质部链状结构复杂性的选择压力。
附：英文原文
Title: Hydraulic failure as a primary driver of xylem network evolution in early vascular plants
Author: Martin Bouda, Brett A. Huggett, Kyra A. Prats, Jay W. Wason, Jonathan P. Wilson, Craig R. Brodersen
Issue&Volume: 2022-11-11
Abstract: The earliest vascular plants had stems with a central cylindrical strand of water-conducting xylem, which rapidly diversified into more complex shapes. This diversification is understood to coincide with increases in plant body size and branching; however, no selection pressure favoring xylem strand-shape complexity is known. We show that incremental changes in xylem network organization that diverge from the cylindrical ancestral form lead to progressively greater drought resistance by reducing the risk of hydraulic failure. As xylem strand complexity increases, independent pathways for embolism spread become fewer and increasingly concentrated in more centrally located conduits, thus limiting the systemic spread of embolism during drought. Selection by drought may thus explain observed trajectories of xylem strand evolution in the fossil record and the diversity of extant forms.
DOI: add2910
Source: https://www.science.org/doi/10.1126/science.add2910