Experimental fossilization of early plant lipids — tracing incipient terrestrialization using a comparative approach with extant bryophytes and Cambrian-Silurian sediments

藻类向植物的转变以及对大陆领域的征服是一个复杂的过程，这是由生物化学途径的进化创新所促成的。其中包括藻类和植物之间不同的萜类化合物和其他次级代谢产物的生物合成的变化，这些变化可能已经记录在岩石记录中。跟踪早期的terrestrialization过程，即它的时间，模式和范围是最重要的了解更大的地球系统的变化，在整个终端新元古代和早古生代。碳埋藏速率的加快、海洋氧化还原结构的变化、营养调节的初级生产力和动物的爆炸性辐射，都可能间接受到最早期植物征服土地的影响。利用化石记录追踪最古老的植物是复杂的，因为在陆地环境中保存得很差，而早期的孢子非常罕见。化石脂质可以提供一个解决方案。然而，在最早的古生代沉积沉积物中的早期分支植物的分子残留物迄今为止没有得到足够的关注，这可能部分是由于我们对这些早期系统发育分支的分子特征的知识仍然很少，这些分支跨越藻类到植物的过渡（即轮藻，地钱和苔藓）。在这里，我提出了一个双重的方法，其中现代生物质的物种将“人工老化”，使用热解和催化氢化，以获得更好的了解特征早期植物生物标志物，而沉积岩从澳大利亚的三个陆源影响序列，跨越寒武纪和奥陶纪将进行系统的研究，以找到任何痕迹的藻类植物过渡。这项研究的结果不仅有可能揭示藻类向植物过渡过程中萜类化合物生物合成的进化变化，而且还可能揭示陆地领域初期殖民化的更多情况，从而限制触发因素，促进因素和全球后果。

The algae-to-plant transition and associated conquest of the continental realm was a complex process, enabled by evolutionary innovation of biochemical pathways. Amongst these are changes in the biosynthesis of terpenoids and other secondary metabolites that differ between algae and plants, and which may have been recorded in the rock record. Tracing the incipient terrestrialization process—i.e. its timing, mode, and extent—is of paramount importance for understanding larger Earth system changes across the terminal Neoproterozoic and early Paleozoic. Enhanced rates of carbon burial, changes in the marine redox structure, nutrient-modulated primary productivity and the explosive radiation of animals may all have been indirectly affected as a consequence of the conquest of land by the earliest plants. Tracing the oldest plants using the fossil record is complicated due to generally poor preservation in terrestrial environments, whilst early spores are exceedingly rare. Fossil lipids can offer a solution. Yet the molecular remnants of early-branching plants in earliest Paleozoic sedimentary deposits have thus far received insufficient attention, which is likely partially due to the fact that our knowledge of molecular signatures of these early phylogenetic branches spanning the algae-to-plant transition (i.e. charophytes, liverworts and bryophytes) is still sparse. Here I propose a dual approach, in which modern biomass of said species will be ‘artificially aged’ using pyrolysis and catalytic hydrogenation in order to obtain a better understanding of characteristic early plant biomarkers, whilst sedimentary rocks from three terrigenous-influenced sequences from Australia, spanning the Cambrian and Ordovician will be systematically studied in order to find any traces of the algae-to-plant transition. The outcomes of this study not only carry the potential to reveal evolutionary changes in terpenoid biosynthesis across the algae-to-plant transition, but may also shed more light on the incipient colonization of the terrestrial realm, thereby placing constraints on triggers, facilitators and global consequences.