DNA markers provide insight about common lime in historical plantings - An example from the Royal Danish Gardens

摘要

As part of the restoration process of an avenue of common lime (Tilia x europaea) from 1760 in the Royal Danish Gardens, all remaining trees were genotyped with DNA markers before they were felled. As such, information about the nature of the plant material (clonal versus non-clonal) and mode of propagation was obtained, revealing that a single clone constituted 92% of the remaining trees (106 out of 115). Five trees were of another clone, while the remaining four trees had unique genotypes. Mode of clonal propagation was most likely layering since the genotype of the crown and the roots of a subsample of the trees had the same genotype. Trees from four other locations with historical avenues/plantings from the 17th century were also genotyped. The two clones registered in the first location were also found at the other four locations. Of 76 trees from the other historical avenues/plantings, only two trees did not belong to either of the two clones. Genotyping of commercial common lime trees that would be planted in place of the felled trees during the restoration project was also performed. Samples of 20 newly planted trees all possessed the same genotype as the majority of the old felled trees and, thereby, were the same clone as the trees planted nearly 250 years ago. Altogether, the current study shows that the genetic diversity of common lime planted in Danish historical plantings is extremely narrow, and that the same clones have been produced for decades/centuries by private nurseries in the Netherlands and Germany. It also provides evidence that it is possible to obtain the same genetic material as originally planted when common lime trees are to be replaced in historical plantings. Furthermore, the utility of DNA markers in the management of plant material in parks is demonstrated