Environmental Research Institute, University of the Highlands and Islands, Castle Street, Thurso, KW14 7JD, Scotland, UK.
Physiol Plant. 2012 Oct;146(2):160-72. doi: 10.1111/j.1399-3054.2012.01593.x. Epub 2012 Apr 10.
The heathland lichen Cladonia portentosa was collected from sites in mainland Britain differing either in rates of wet N deposition or in annual mean N concentration in rainfall based on a modelled data set. Methanolic extracts of thalli were analyzed by liquid chromatography time-of-flight mass spectrometry to yield metabolic profiles. Differences between sites in metabolite concentration were quantified using multivariate statistical tools and used to identify potential biomarker molecules. The abundances of three structurally related betaine lipids showed an increase with increasing modelled N deposition to a threshold of 22.3 kg ha(-1) year(-1) after which they remained constant. In contrast, the abundance of a phosphatidylcholine (PC) lipid showed concomitant decrease. Correlations of the identified biomarkers with N deposition and precipitation were stronger than those with N concentrations. The results presented in this study clearly show that N enrichment associated with tissue P limitation changes lipid composition, leading to shifts from PCs to betaine lipids, and that these lipids identified have the potential to be used as biomarkers for nitrogen enrichment.
从英国大陆不同湿氮沉积速率或基于模型数据集的年平均氮浓度的地点采集了荒地地衣 Cladonia portentosa。用液质联用飞行时间质谱法分析藻体的甲醇提取物以产生代谢谱。使用多元统计工具量化了代谢物浓度在站点之间的差异，并用于鉴定潜在的生物标志物分子。三种结构相关的甜菜碱脂质的丰度随着模型化氮沉积的增加而增加，达到 22.3 公斤/公顷/年后保持不变。相比之下，一种磷脂酰胆碱 (PC) 脂质的丰度则相应减少。鉴定出的生物标志物与氮沉积和降水的相关性强于与氮浓度的相关性。本研究的结果清楚地表明，与组织磷限制相关的氮富集改变了脂质组成，导致从 PC 向甜菜碱脂质的转变，并且这些鉴定出的脂质有可能被用作氮富集的生物标志物。
