Cryo-scanning electron microscopy observations of vessel content during transpiration in walnut petioles. Facts or artefacts?
Cryo-scanning electron microscopy observations of vessel content during transpiration in walnut petioles. Facts or artefacts?
复制标题
核桃叶柄蒸腾过程中导管内容物的冷冻扫描电子显微镜观察。
DOI：
10.1016/s0981-9428(01)01288-8
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发表时间：
2001
影响因子：
6.5
通讯作者：
Cheng X. Huang
中科院分区：
文献类型：
--
作者：
M. Canny;M. Mccully;Cheng X. Huang
低温扫描电镜技术用于稳定和量化蒸腾植物血管中栓塞的可靠性最近受到了批评，理由是观察到的栓塞是冷冻的假象。所用的测试之一是比较在蒸腾核桃叶（核桃L.）冷冻完整的树，与导管内容物和类似的样品，其木质部压力已恢复到大气压通过切断叶片在水中测得的水力传导率的低温扫描电镜图像。在完整的冷冻脊柱中发现的栓塞在切割脊柱中不存在，并且高脊柱导水率表明类似的没有栓塞。我们表明，作者的结论是错误的，因为他们的测试产生了不同的人工制品。当在染料溶液下切割叶柄时，很明显，浸泡溶液被吸入栓塞的血管并填充它们。因此，低温扫描电镜图像和高导水率的标本制备的这种技术并不表明在完整的植物中的木质部的内容。事实上，这种人工制品可能（与染料一起）用于测量完整植物中的栓塞。冷冻SEM中观察到的栓塞最不可能是伪影。发表的工作，也表明栓塞和他们的再填充蒸腾植物的技术，不涉及冻结进行审查。
The reliability of the cryo-SEM technique for stabilizing and quantifying embolisms in vessels of transpiring plants has recently been criticized, on the grounds that the embolisms observed are artefacts of the freezing. One of the tests used was a comparison of the embolisms found in rachises of transpiring walnut leaves (Juglans regia L.) frozen intact on the tree, with both cryo-SEM images of vessel contents and the measured hydraulic conductivity of similar samples whose xylem pressure had been returned to atmospheric pressure by cutting the leaves off under water. Embolisms found in intact frozen rachises were not present in cut rachises, and the high rachis hydraulic conductivities indicated a similar absence of embolisms. We show that the authors’ conclusions are wrong because their test produces a different artefact. When the petiole is cut under dye solution it is obvious that the immersing solution is drawn into the embolized vessels and fills them. Thus, the cryo-SEM images and the high hydraulic conductivities of specimens prepared by this technique do not indicate the contents of the xylem in the intact plant. In fact, this artefact may perhaps be used (with the dye) to measure the embolisms in the intact plant. The embolisms seen in the cryo-SEM are most unlikely to be artefacts. The published work that also shows embolisms and their refilling in transpiring plants by techniques involving no freezing is reviewed.