Because plants do not possess a defined germline, deleterious somatic mutations can be passed to gametes, and a large number of cell divisions separating zygote from gamete formation may lead to many mutations in long-lived plants. We sequenced the genome of two terminal branches of a 234-year-old oak tree and found several fixed somatic single-nucleotide variants whose sequential appearance in the tree could be traced along nested sectors of younger branches. Our data suggest that stem cells of shoot meristems in trees are robustly protected from the accumulation of mutations.
This work was funded by the University of Lausanne through a supportive grant from the University rectorate and by the Swiss National Science Foundation (Agora Grant CRAGI3_145652). The Pacific Biosciences RS II sequencing was performed at the Lausanne Genomic Technologies Facility (GTF). The purchase of the GTF’s RS II instrument was financed in part by the Loterie Romande through the Fondation pour la Recherche en Médecine Génétique. We thank K. Harshman, J. Weber and M. Dupasquier from the GTF for sequencing. We thank C. Kuhlemeier for sharing unpublished results, J. Tercier for tree-ring analysis, Transistor communication for graphical production of the 3D oak, Woodtli + Leuba SA for sample collection, N. Guex for advice on SNV identification and J.-J. Strahm and M. Bonetti for providing oak images.