Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
Plant Cell Environ. 2014 Jan;37(1):153-61. doi: 10.1111/pce.12141. Epub 2013 Jun 30.
Despite decades of research on plant drought tolerance, the physiological mechanisms by which trees succumb to drought are still under debate. We report results from an experiment designed to separate and test the current leading hypotheses of tree mortality. We show that piñon pine (Pinus edulis) trees can die of both hydraulic failure and carbon starvation, and that during drought, the loss of conductivity and carbohydrate reserves can also co-occur. Hydraulic constraints on plant carbohydrate use determined survival time: turgor loss in the phloem limited access to carbohydrate reserves, but hydraulic control of respiration prolonged survival. Our data also demonstrate that hydraulic failure may be associated with loss of adequate tissue carbohydrate content required for osmoregulation, which then promotes failure to maintain hydraulic integrity.
尽管对植物耐旱性的研究已经进行了几十年，但树木因干旱而死亡的生理机制仍存在争议。我们报告了一项旨在分离和测试当前树木死亡率主要假设的实验结果。我们表明，矮松（Pinus edulis）树木可能因水力衰竭和碳饥饿而死亡，并且在干旱期间，导水率和碳水化合物储备的丧失也可能同时发生。对植物碳水化合物利用的水力限制决定了存活时间：韧皮部的膨压丧失限制了对碳水化合物储备的利用，但水力控制呼吸延长了存活时间。我们的数据还表明，水力衰竭可能与维持渗透压所需的足够组织碳水化合物含量的丧失有关，从而导致无法维持水力完整性。
