School of Plant Science, University of Tasmania, Hobart, Tasmania, Australia.
New Phytol. 2010 Oct;188(2):533-42. doi: 10.1111/j.1469-8137.2010.03393.x. Epub 2010 Jul 28.
• Motivated by the urgent need to understand how water stress-induced embolism limits the survival and recovery of plants during drought, the linkage between water-stress tolerance and xylem cavitation resistance was examined in one of the world's most drought resistant conifer genera, Callitris. • Four species were subjected to drought treatments of -5, -8 and -10 MPa for a period of 3-4 wk, after which plants were rewatered. Transpiration, basal growth and leaf water potential were monitored during and after drought. • Lethal water potential was correlated with the tension producing a 50% loss of stem hydraulic conductivity. The most resilient species suffered minimal embolism and recovered gas exchange within days of rewatering from -10 MPa, while the most sensitive species suffered major embolism and recovered very slowly. The rate of repair of water transport in the latter case was equal to the rate of basal area growth, indicating xylem reiteration as the primary means of hydraulic repair. • The survival of, and recovery from, water stress in Callitris are accurately predicted by the physiology of the stem water-transport system. As the only apparent means of xylem repair after embolism, basal area growth is a critical part of this equation.
受理解水分胁迫如何引发栓塞从而限制植物在干旱中的生存和恢复这一迫切需求的驱动，本研究旨在探讨世界上最耐旱的针叶树属之一——翠柏属中木质部抗空化能力与水分胁迫耐受性之间的联系。
选择 4 个翠柏种进行为期 3-4 周的-5、-8 和-10 MPa 的干旱处理，然后再进行复水处理。在干旱和复水过程中监测蒸腾、基径生长和叶片水势。
致死水势与产生木质部水力导率 50%丧失的张力相关。最具弹性的物种在从-10 MPa 复水后几天内遭受最小的栓塞且气体交换迅速恢复，而最敏感的物种遭受严重的栓塞且恢复非常缓慢。在后一种情况下，水运输的修复速率与基径生长速率相等，表明木质部重复是水力修复的主要手段。
翠柏种的水分胁迫生存和恢复可由茎水分运输系统的生理学准确预测。由于栓塞后木质部修复的唯一明显手段，基径生长是该方程的关键部分。
