Sporopollenin chemistry and its durability in the geological record: an integration of extant and fossil chemical data across the seed plants
Sporopollenin chemistry and its durability in the geological record: an integration of extant and fossil chemical data across the seed plants
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DOI：
10.1111/pala.12523
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发表时间：
2021-01-31
期刊：
影响因子：
2.6
通讯作者：
Dupont-Nivet, Guillaume
中科院分区：
文献类型：
--
作者：
Jardine, Phillip E.;Hoorn, Carina;Dupont-Nivet, Guillaume
孢粉素是一种高抗性生物聚合物，形成花粉和孢子（孢子形态）的外壁。近年来，孢粉素化学的研究为孢粉学研究开辟了新的途径，包括形态隐蔽类群的化学分类。然而，直接整合现存和化石孢粉素化学数据的尝试有限。特别重要的是样品处理的影响，以分离孢粉素从新鲜的sporomorphs，以及一旦sporomorphs进入地质记录发生的化学变化的程度。在这里，我们探讨这些问题，利用傅里叶变换红外（FTIR）显微光谱数据从现存的和化石草，白刺（草原植物），针叶树花粉。我们显示了98%的分类成功率在亚科水平与现存的草花粉，表现出强大的分类签名在孤立的孢粉素。然而，我们也揭示了现存的和化石的孢粉素，这可以绑定到两个早期成岩作用的变化上的sporomorphs和样品处理的化学衍生物之间的化学差异。我们的研究结果表明，直接整合现存的和晚第四纪的化学数据应该是易于处理的，只要保持可比的样品处理程序。然而，现存的和更深的时间孢子形态之间的一致差异表明，使用现存的训练集分类化石标本将是具有挑战性的。因此，需要进一步的工作来了解和模拟成岩过程对孢粉化学的影响。
Sporopollenin is a highly resistant biopolymer that forms the outer wall of pollen and spores (sporomorphs). Recent research into sporopollenin chemistry has opened up a range of new avenues for palynological research, including chemotaxonomic classification of morphologically cryptic taxa. However, there have been limited attempts to directly integrate extant and fossil sporopollenin chemical data. Of particular importance is the impact of sample processing to isolate sporopollenin from fresh sporomorphs, and the extent of chemical changes that occur once sporomorphs enter the geological record. Here, we explore these issues using Fourier transform infrared (FTIR) microspectroscopy data from extant and fossil grass, Nitraria (a steppe plant), and conifer pollen. We show a 98% classification success rate at subfamily level with extant grass pollen, demonstrating a strong taxonomic signature in isolated sporopollenin. However, we also reveal substantial chemical differences between extant and fossil sporopollenin, which can be tied to both early diagenetic changes acting on the sporomorphs and chemical derivates of sample processing. Our results demonstrate that directly integrating extant and late Quaternary chemical data should be tractable as long as comparable sample processing routines are maintained. Consistent differences between extant and deeper time sporomorphs, however, suggests that classifying fossil specimens using extant training sets will be challenging. Further work is therefore required to understand and simulate the effects of diagenetic processes on sporopollenin chemistry.