Genetic and Epigenetic Mechanisms of Longevity in Forest Trees

Trees are unique in terms of development, sustainability and longevity. Some species have a record lifespan in the living world, reaching several millennia. The aim of this review is to summarize the available data on the genetic and epigenetic mechanisms of longevity in forest trees. In this review, we have focused on the genetic aspects of longevity of a few well-studied forest tree species, such as Quercus robur, Ginkgo biloba, Ficus benghalensis and F. religiosa, Populus, Welwitschia and Dracaena, as well as on interspecific genetic traits associated with plant longevity. A key trait associated with plant longevity is the enhanced immune defense, with the increase in gene families such as RLK, RLP and NLR in Quercus robur, the expansion of the CC-NBS-LRR disease resistance families in Ficus species and the steady expression of R-genes in Ginkgo biloba. A high copy number ratio of the PARP1 family genes involved in DNA repair and defense response was found in Pseudotsuga menziesii, Pinus sylvestris and Malus domestica. An increase in the number of copies of the epigenetic regulators BRU1/TSK/MGO3 (maintenance of meristems and genome integrity) and SDE3 (antiviral protection) was also found in long-lived trees. CHG methylation gradually declines in the DAL 1 gene in Pinus tabuliformis, a conservative age biomarker in conifers, as the age increases. It was shown in Larix kaempferi that grafting, cutting and pruning change the expression of age-related genes and rejuvenate plants. Thus, the main genetic and epigenetic mechanisms of longevity in forest trees were considered, among which there are both general and individual processes.