Testing the 'rare pit' hypothesis for xylem cavitation resistance in three species of Acer
Testing the 'rare pit' hypothesis for xylem cavitation resistance in three species of Acer
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DOI：
10.1111/j.1469-8137.2009.02776.x
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发表时间：
2009-01-01
期刊：
影响因子：
9.4
通讯作者：
Adler, Frederick R.
中科院分区：
文献类型：
--
作者：
Christman, Mairgareth A.;Sperry, John S.;Adler, Frederick R.
对木质部空化具有更大脆弱性的真双子叶被子植物倾向于具有具有更大的导管间凹坑总面积的导管，这激发了“罕见凹坑”假说：每个容器的凹坑越多，容器的单个空气播种凹坑的泄漏可能越大，并且空泡在容器之间传播的空气播种阈值越低。在这里，我们证明了假设的可行性，使用概率理论来模拟空气通过空气注入的茎的轴向传播。在存在罕见的，泄漏的坑，空气播种压力通过短茎与几个容器结束串联应低;压力应增加更长的茎更多的端壁必须breaked.Measurements三个槭属物种符合密切的模型预测，确认泄漏的坑的罕见存在。该模型表明，坑空气播种或低于平均空化压力（MCP）发生在同样低的频率在所有物种。模型预测的平均端壁空气播种压力与物种的MCPs密切匹配。物种脆弱性的差异主要归因于最泄漏坑的频率差异，而不是每个容器的坑数或面积。膜特性的调整和每个容器的点蚀程度显然联合收割机影响跨物种的抗空化性。New Phytologist（2009）182：664-674 doi：10.1111/j.1469-8137.2009.02776.x。
Eudicot angiosperms with greater vulnerability to xylem cavitation tend to have vessels with greater total area of inter-vessel pits, which inspired the 'rare pit' hypothesis: the more pits per vessel, by chance the leakier will be the vessel's single air-seeding pit and the lower the air-seeding threshold for cavitation to spread between vessels.Here, we demonstrate the feasibility of the hypothesis, using probability theory to model the axial propagation of air through air-injected stems. In the presence of rare, leaky pits, air-seeding pressures through short stems with few vessel ends in series should be low; pressures should increase in longer stems as more end-walls must be breached.Measurements on three Acer species conformed closely to model predictions, confirming the rare presence of leaky pits. The model indicated that pits air-seeding at or below the mean cavitation pressure (MCP) occurred at similarly low frequencies in all species. Average end-wall air-seeding pressures predicted by the model closely matched species' MCPs.Differences in species' vulnerability were primarily attributed to differences in frequency of the leakiest pits rather than pit number or area per vessel. Adjustments in membrane properties and extent of pitting per vessel apparently combine to influence cavitation resistance across species.New Phytologist (2009) 182: 664-674 doi: 10.1111/j.1469-8137.2009.02776.x.