Societal Impact Statement Combining natural and social science approaches to conduct archeological research on wooden cultural relics is important for exploring major aspects of ancient... Show moreSocietal Impact Statement Combining natural and social science approaches to conduct archeological research on wooden cultural relics is important for exploring major aspects of ancient civilizations. The Forbidden City in Beijing, China, is the largest existing wooden palace complex in the world. We examined ancient DNA of imperial wood "Nanmu" specimens taken from representative structural components of the Forbidden City, in order to provide a new perspective on the long-standing dispute about its species. This allowed us to accurately identify and properly restore these wooden artifacts and improved our understanding of the past interactions between plant distribution, forest resources, and human activities. Exploring the life styles and production methods of past generations using plant resources can help us to improve our understanding of human civilization. Nanmu, known for its high wood quality, was exclusively used for imperial palace construction in the 15th-19th centuries in China, yet its species has been a subject of long-standing debate. Here, we revisit this unresolved problem, using morphology and ancient DNA (aDNA) to analyze 21 centuries-old Nanmu specimens sampled from representative palaces of the Forbidden City. Cytochemical staining demonstrated that endogenous aDNA sporadically occurs in the wood ray parenchyma cells of Nanmu specimens. High-quality plastid genomes were retrieved from archeological woods for the first time via an aDNA capture method, with 90%-100% coverage (137,663-152,805 bp) and sequence depths of 27.05- to 1409.94-fold. Utilizing these ancient genomes, our results demonstrate that Phoebe zhennan and Phoebe hui are most likely the main species of Nanmu in the Forbidden City. This finding diverges from the prevailing view that Nanmu encompasses woods from the whole genus Phoebe and even its close relative Machilus. It also shows that stringent criteria were used when selecting construction materials for the Forbidden City. By combining morphological traits with aDNA analyses, we provide a new solution for identifying the species of timber used for ancient architecture, and we increase our understanding of the way in which forest resources were recognized and utilized by our ancestors despite the lack of a plant taxonomic framework in ancient times. Show less
Plants produce an astonishing variety of secondary metabolites (SMs) which are thought to play vital roles in the fitness of plants through ecological interactions. The most characteristic features... Show morePlants produce an astonishing variety of secondary metabolites (SMs) which are thought to play vital roles in the fitness of plants through ecological interactions. The most characteristic features of SMs are their striking chemical diversity and inter- or intraspecific variation. Due to the large number, high structural diversity and multifunctionality of SMs, it is still an ongoing challenge to understand how this SM diversity comes about, and why such a large diversity is maintained in nature. In this thesis this question was studied using the pyrrolizidine alkaloids (PAs) of Jacobaea species as the study system from an evolutionary and biosynthetic perspective. PA variations were studied among and within Jacobaea species, and species-specific PA profiles were observed. In order to understand how PA diversity is related to species phylogeny, the evolutionary histories and phylogenetic signals of individual PAs were investigated under the phylogenetic context of Jacobaea species and no strong phylogenetic signals were found. To shed light on the mechanisms underlying PA diversity, a gene-to-metabolite approach targeting cytochrome P450 monooxygenases which play an important role in the evolution of chemical diversity was applied to study their involvement in PA biosynthesis and PA diversity. Show less
Chen, Y.; Klinkhamer, P.G.L.; Memelink, J.; Vrieling, K. 2020
