Destruction, decay, and preservation: Early fossilization of leaf compressions

破坏、腐烂和保存：叶压缩物的早期石化

• 批准号: 465275616
• 负责人: Professorin Dr. Gabriele Bierbaum
• 金额: --
• 依托单位: Institut für Geologische Wissenschaften
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/465275616?language=en
• 关键词: Destruction; decay; preservation; Early; fossilization

Among the various fossilization pathways open to plants, wood mineralization and leaf carbonization are the routes most commonly taken, which lead to the formation of silicified wood and leaf compressions. Through the process of carbonization, leaf compressions are frequently produced in freshwater facies such as ponds, lakes, and rivers. In freshwater conservation lagerstätten, the excellent preservation of fossil animals is attributed to the protective properties of bacterial biofilms covering the decaying organism. Yet little is known about the influence of microorganisms and biofilm formation on the preservation in leaves. For a leaf to become fossilized, it must first enter a body of water, for example, by wind or the flow of water. Conventional wisdom says that the leaf must then rapidly enter an anoxic environment to become preserved. However, we know that leaf colonization and degradation by bacterial or fungal microbes can occur early on, well before the leaf enters an oxygen-less environment. The rate of microbial colonization on and in the leaf may depend on intrinsic factors such as cuticle morphology. It has also been observed that the development of a biofilm on leaves can lead to the natural development of a mineral encrustation, which would protect a leaf surface from abrasion and damage from transport and invertebrate herbivory, slow down decay from further bacterial activity, as well preserve morphological features of the leaf. However, it is unknown which microorganisms, or even whether they are bacterial or fungal, are responsible for decay or fossilization. Here we begin an interdisciplinary study on the early stages of fossilization in which we investigate the timing and development of the microbes and biofilms involved in the destruction, decay, and preservation of leaves. Central to our research is DNA extraction and microbiome sequencing to identify and characterize the microbes involved in the biodegradation or preservation processes. Experiments of several weeks' duration will be conducted on four plant groups that are found in varying frequencies in the Cenozoic plant record—Nymphaea water lily leaves, Equisetum stems, Pinus needles, and Liquidambar leaves—in both natural freshwater settings and in experimental aquaria. In the case of Liquidambar, trials with green leaves, as well as with autumnal yellow and red leaves, will be run to check for differences in pathogen defense due to natural leaf pigments. Taxonomic determination of the microbial growth on the leaves, successional changes in the microbial flora, fluctuations in water ion chemistry, and mineral accumulation on the leaf surfaces, will be tracked throughout the experiments. Intrinsic differences in leaves such as cuticle morphology will also be studied. Interdisciplinary research on the next stage of leaf fossilization—the development of a mineral veil or encrustation under experimental conditions—will continue on the same plant groups in Project C4.

在植物的硅化途径中，木材矿化和叶片碳化是最常见的途径，它们导致硅化木材和叶片压缩的形成。通过碳化过程，叶压缩经常产生于淡水相，如池塘，湖泊和河流。在淡水保护区，动物化石的良好保存归功于覆盖在腐烂生物体上的细菌生物膜的保护特性。然而，关于微生物和生物膜形成对叶片保存的影响知之甚少。一片叶子要变成绿色，它必须首先进入水体，例如，通过风或水流。传统观点认为，叶子必须迅速进入缺氧环境才能保存下来。然而，我们知道，细菌或真菌微生物的叶片定殖和降解可以在早期发生，远在叶片进入无氧环境之前。微生物在叶上和叶中的定殖率可能取决于内在因素，如角质层形态。还已经观察到，叶子上生物膜的发展可以导致矿物结壳的自然发展，这将保护叶子表面免受运输和无脊椎动物食草动物的磨损和损害，减缓进一步细菌活动引起的腐烂，以及保护叶子的形态特征。然而，目前还不知道哪些微生物，甚至是细菌或真菌，负责腐烂或腐烂。在这里，我们开始一个跨学科的研究，在早期阶段，我们调查的时间和发展的微生物和生物膜参与破坏，腐烂和保存的树叶。我们研究的核心是DNA提取和微生物组测序，以识别和表征参与生物降解或保存过程的微生物。实验将进行几个星期的时间在四个植物群体，发现在不同的频率在新生代植物记录-睡莲叶，木贼茎，松针，和枫香lephan-in两个自然淡水设置和实验水族箱。在枫香属的情况下，将用绿色叶以及秋天的黄色和红色叶进行试验，以检查由于天然叶色素引起的病原体防御的差异。在整个实验过程中，将跟踪叶片上微生物生长的分类学测定、微生物植物群的演替变化、水离子化学的波动和叶片表面的矿物质积累。叶的内在差异，如角质层形态也将进行研究。在C4项目中，将继续对相同的植物群进行跨学科研究，研究下一阶段的叶结垢--在实验条件下形成矿物质面纱或结壳。