Osmotic adjustment leads to anomalously low estimates of relative water content in wheat and barley
Osmotic adjustment leads to anomalously low estimates of relative water content in wheat and barley
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DOI：
10.1071/fp08157
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发表时间：
2008-01-01
影响因子：
3
通讯作者：
Passioura, John B.
中科院分区：
文献类型：
--
作者：
Boyer, John S.;James, Richard A.;Passioura, John B.
相对含水量(RWC)被广泛地用来确定植物相对于其充分膨胀状态的水分状况。然而，植物通常会根据盐度或水分亏缺进行渗透调节，这会保持膨胀压力，并模糊了“充分膨胀”的定义。为探讨这一问题，用等压湿度法测定了大麦和硬粒小麦成熟叶片的膨胀率。硬粒小麦)，或在不同程度脱水的土壤中种植的面包小麦(普通小麦)。渗透调节在所有植物中都保持了膨胀性，但尽管一些盐化植物完全保持了膨胀性，它们的叶片相对含水量却大幅下降。这是因为作为RWC测量的一部分，当样品漂浮在水面上时，多余的水被吸收了。吸收错误地增加了“完全膨胀”状态的重量，导致RWC异常低10-15%。细胞溶液被分泌到细胞间隙，并在显微镜下观察，这是一种鼓励所有RWC测量的测试。人们建议了几种替代方法来补充组织的水分，同时将多余的水分吸收降至最低，但似乎没有简单的定义来定义“充分肿胀”。一般来说，渗透调节和膨胀率的直接测量是首选的。
Relative water content (RWC) is used extensively to determine the water status of plants relative to their fully turgid condition. However, plants often adjust osmotically to salinity or water deficit, which maintains turgor pressure and obscures the definition of 'full turgidity'. To explore this problem, turgor was measured by isopiestic psychrometry in mature leaf blades of barley (Hordeum vulgare) and durum wheat (Triticum turgidum ssp. durum) salinised to 150 mM NaCl, or bread wheat (Triticum aestivum) grown in soil dehydrated to varying degrees. Osmotic adjustment maintained turgor in all the plants but despite full maintenance in some of the salinised plants, their leaf RWC decreased substantially. This occurred because excess water was absorbed while the samples were floated on water as part of the RWC measurement. The absorption falsely increased the weight of the 'fully turgid' condition, causing RWC to be anomalously low by 10-15%. Cell solution was secreted into intercellular spaces and was seen under a microscope, which is a test encouraged for all RWC measurements. Several alternate methods are suggested for rehydrating tissues while minimising excess water absorption, but no simple definition of 'full turgidity' seems possible. In general, direct measurements of osmotic adjustment and turgor are preferred.