Department of Chemical Ecology, Bielefeld University, Bielefeld, Germany.
Institute of Biodiversity, Friedrich Schiller University Jena, Jena, Germany.
Metabolomics. 2023 Jun 23;19(7):62. doi: 10.1007/s11306-023-02026-6.
Assessing intraspecific variation in plant volatile organic compounds (VOCs) involves pitfalls that may bias biological interpretation, particularly when several laboratories collaborate on joint projects. Comparative, inter-laboratory ring trials can inform on the reproducibility of such analyses.
In a ring trial involving five laboratories, we investigated the reproducibility of VOC collections with polydimethylsiloxane (PDMS) and analyses by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). As model plant we used Tanacetum vulgare, which shows a remarkable diversity in terpenoids, forming so-called chemotypes. We performed our ring-trial with two chemotypes to examine the sources of technical variation in plant VOC measurements during pre-analytical, analytical, and post-analytical steps.
Monoclonal root cuttings were generated in one laboratory and distributed to five laboratories, in which plants were grown under laboratory-specific conditions. VOCs were collected on PDMS tubes from all plants before and after a jasmonic acid (JA) treatment. Thereafter, each laboratory (donors) sent a subset of tubes to four of the other laboratories (recipients), which performed TD-GC-MS with their own established procedures.
Chemotype-specific differences in VOC profiles were detected but with an overall high variation both across donor and recipient laboratories. JA-induced changes in VOC profiles were not reproducible. Laboratory-specific growth conditions led to phenotypic variation that affected the resulting VOC profiles.
Our ring trial shows that despite large efforts to standardise each VOC measurement step, the outcomes differed both qualitatively and quantitatively. Our results reveal sources of variation in plant VOC research and may help to avoid systematic errors in similar experiments.
评估植物挥发性有机化合物（VOC）的种内变异涉及可能导致生物解释产生偏差的陷阱，尤其是当几个实验室合作开展联合项目时。比较性的、实验室间的环试验可以提供此类分析重现性的信息。
在涉及五个实验室的环试验中，我们研究了使用聚二甲基硅氧烷（PDMS）进行 VOC 收集和热解吸-气相色谱-质谱（TD-GC-MS）分析的重现性。我们选择具有显著萜烯多样性的 Tanacetum vulgare 作为模式植物，形成所谓的化学型。我们进行了环试验，使用两种化学型来检查在预分析、分析和后分析步骤中植物 VOC 测量中的技术变异的来源。
在一个实验室中生成单克隆根扦插，并分发给五个实验室，在这些实验室中，植物在特定的实验室条件下生长。在施用茉莉酸（JA）前后，从所有植物上用 PDMS 管收集 VOC。此后，每个实验室（供体）将一组管发送给其他四个实验室（受体），受体用自己的既定程序进行 TD-GC-MS。
检测到 VOC 图谱的化学型特异性差异，但供体和受体实验室的总体差异很大。JA 诱导的 VOC 图谱变化不可重现。特定于实验室的生长条件导致影响产生的 VOC 图谱的表型变异。
我们的环试验表明，尽管为标准化每个 VOC 测量步骤做出了巨大努力，但结果在定性和定量上都有所不同。我们的结果揭示了植物 VOC 研究中的变异源，并可能有助于避免类似实验中的系统误差。
