SEVERAL CONTROVERSIAL VIEWPOINTS IN STUDYING THE CAVITATION OF XYLEM VESSELS
SEVERAL CONTROVERSIAL VIEWPOINTS IN STUDYING THE CAVITATION OF XYLEM VESSELS
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DOI：
10.17521/cjpe.2004.0018
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
D. Fan;Zongqiang Xie
中科院分区：
文献类型：
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作者：
D. Fan;Zongqiang Xie
木质部空化/栓塞是一个受到广泛关注的话题，通常被认为是对活着的植物的潜在威胁，因为它降低了轴向导水系统的电导率。本文列举了有关木质部导管空化研究的几种有争议的观点，并综述了木质部导管空化研究的现状和进展。超声波传感器可以直接检测木质部空化的发生，但这种方法有一定的局限性。除超声波传感器外，目前用于研究木质部空化/栓塞症的几乎所有方法都需要破坏性采样。最近，一种基于高分辨率磁共振成像技术的非侵入性方法被提出。压力室试验与木质部压力探头检测木质部容器张力的结果存在较大差异。至少有四个可能的原因可以解释这种差异。木质部导管的解剖特征与抗空化能力之间的关系是复杂的，可能表现出物种特异性的反应。木质部空化诱导气孔关闭的潜在机制尚不清楚。木质部导管对空化的抗性与植物适应水分胁迫的能力之间的关系尚无定论。用水重新填充的栓塞物血管怎么办？将这一过程仅仅归因于根压力的机制是有风险的，因为现在有一些证据表明，其他机制也参与其中。总体而言，需要进一步的努力来澄清和解决这些不确定性和差异，以便我们更好地了解木质部导管的空化和植物的输水系统。
Xylem cavitation/embolism, a topic that has received extensive attention, is generally seen as a potential threat for living plants because it lowers the conductivity of the axial water-conducting system. In this paper, several controversial viewpoints about studying the cavitation of xylem vessels were listed, and current efforts and advances in this field were reviewed. Ultrasonic sensors can be used to directly detect the occurrence of xylem cavitation; however, this method has some limitations. Almost all current methods used to study xylem cavitation/embolism, except for the ultrasonic sensor, requires destructive sampling. Recently, a noninvasive method based on high-resolution magnetic resonance imaging technique was introduced. Large discrepancies existed between the results of pressure chamber tests and xylem pressure probe, both of which were used to detect the tension of xylem vessels. There are at least four possible reasons to explain this discrepancy. The relationship between the anatomical characteristics and the ability of xylem vessel to resist cavitation is complex and it may show a species-specific response. The underlying mechanism of stomatal closure induced by xylem cavitation is still unclear. There is no general conclusion about the relationship between xylem vessel resistance to cavitation and the capacity of plants to adapt to water-stress. What about the embolized vessels refilled by water? It is risky to attribute this process solely to the mechanism of root pressure, because there is now some evidence that other mechanisms are involved. In general, further efforts are needed to clarify and resolve these uncertainties and discrepancies in order for us to better understand the cavitation of xylem vessels and the water-conducting system of plants.