Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA.
Eastern Forest Environmental Threat Assessment Center, United States Forest Service, Raleigh, NC, USA.
Tree Physiol. 2017 Jan 31;37(1):142-150. doi: 10.1093/treephys/tpw084.
Stable isotope ratios (δ13C and δ18O) of tree-ring α-cellulose are important tools in paleoclimatology, ecology, plant physiology and genetics. The Multiple Sample Isolation System for Solids (MSISS) was a major advance in the tree-ring α-cellulose extraction methods, offering greater throughput and reduced labor input compared to traditional alternatives. However, the usability of the method for resinous conifer species may be limited by the need to remove extractives from some conifer species in a separate pretreatment step. Here we test the necessity of pretreatment for α-cellulose extraction in loblolly pine (Pinus taeda L.), and the efficiency of a modified acetone-based ambient-temperature step for the removal of extractives (i) in loblolly pine from five geographic locations representing its natural range in the southeastern USA, and (ii) on five other common coniferous species (black spruce (Picea mariana Mill.), Fraser fir (Abies fraseri (Pursh) Poir.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), Norway spruce (Picea abies (L.) Karst) and ponderosa pine (Pinus ponderosa D.)) with contrasting extractive profiles. The differences of δ13C values between the new and traditional pretreatment methods were within the precision of the isotope ratio mass spectrometry method used (±0.2‰), and the differences between δ18O values were not statistically significant. Although some unanticipated results were observed in Fraser fir, the new ambient-temperature technique was deemed as effective as the more labor-consuming and toxic traditional pretreatment protocol. The proposed technique requires a separate acetone-inert multiport system similar to MSISS, and the execution of both pretreatment and main extraction steps allows for simultaneous treatment of up to several hundred microsamples from resinous softwood, while the need of additional labor input remains minimal.
树木轮α-纤维素的稳定同位素比值（δ13C 和 δ18O）是古气候学、生态学、植物生理学和遗传学中的重要工具。多样品固相萃取系统（MSISS）是树木轮α-纤维素提取方法的重大进展，与传统方法相比，它具有更高的通量和更低的劳动力投入。然而，由于需要在单独的预处理步骤中去除某些针叶树物种的抽提物，该方法的可用性可能会受到限制。在这里，我们测试了在火炬松（Pinus taeda L.）中提取α-纤维素时预处理的必要性，以及一种改良的基于丙酮的环境温度步骤去除抽提物的效率（i）在来自美国东南部火炬松自然分布的五个地理位置的样品中，以及（ii）在其他五个常见的针叶树种（黑云杉（Picea mariana Mill.）、弗雷泽冷杉（Abies fraseri (Pursh) Poir.）、花旗松（Pseudotsuga menziesii (Mirb.) Franco）、挪威云杉（Picea abies (L.) Karst）和黄松（Pinus ponderosa D.））中的效率，这些树种具有不同的抽提物特征。新的和传统预处理方法之间的 δ13C 值差异在同位素比质谱法的精度范围内（±0.2‰），并且 δ18O 值的差异不具有统计学意义。尽管在弗雷泽冷杉中观察到了一些意想不到的结果，但新的环境温度技术被认为与更耗时和有毒的传统预处理方案一样有效。该技术需要一个单独的、与 MSISS 类似的丙酮惰性多端口系统，预处理和主要提取步骤的执行允许同时处理多达几百个来自树脂软木的微样本，而劳动力投入的需求仍然最小。
