No signs of meristem senescence in old Scots pine

Abstract

Summary1. Ageing and senescence in plants remain poorly understood. Although meristem totipotency may allow woody perennials to be immortal, relative growth and photosynthetic rates typically decline with age. 2.Trees of ages between 129 and 534 years were selected in one of the oldest extant populations of Scots pine. Apical branches were propagated by grafting onto homogeneous juvenile rootstock to eliminate the effects of size and environmental variability and isolate those due to age. The hormonal profile of leaves and seeds along with markers of the physiological status of leaves and their pattern of DNA cytosine methylation were measured 15 years after grafting.3. The percentage of total methylated loci in nuclear DNA increased with increasing meristematic age. However, only very few significant relationships were found between levels of phyto-hormones, pigments or physiological markers either in leaves or seeds and age of the meristem. In addition, shoots grafted from old trees grew as fast as those from younger trees and produced the same number of germinable seeds.4. Synthesis. We conclude that changes in DNA methylation can occur in old trees. The lack of apparent physiological deterioration in the grafted plants suggests that meristem senescence is not the main factor triggering whole-plant ageing in Scots pine.

The longevity of broadleaf deciduous trees in Northern Hemisphere temperate forests: insights from tree-ring series

“…The dendrochronologically verified age limit of 600-700 years can be considered a maximum lifespan reference for the deciduous temperate biome. Considering the increased growth rates maintained by trees at great ages, we believe that this is not a biological limit (i.e., meristem senescence; Mencuccini et al, 2014). A central theme for future studies will be to understand how the geography of rare, severe disturbance agents impacts tree survivorship.…”

A synthesis of radial growth patterns preceding tree mortality

“…When not measured in the original study, DBH was estimated as twice the sum of all previous ring-width measurements. Direct age effects were not considered here assuming that senescence only marginally affects tree function (Mencuccini et al, 2014). Finally, to assess the dependency of the results to the growth data used, g m values were also calculated using basal area increment (BAI; mm 2 ) for trees whose DBH was measured (1000 mortality events).…”

Senescence: Is It Universal or Not?

“…In this case of extreme longevity for a perennial herb, greatly reduced growth rates and the alternative use of belowground meristems are considered to hold the secret to long life [15]. Other recent studies using woody perennials support the contention that perennial plants can escape senescence (or at least achieve long life) in the wild by growing very slowly and keeping meristems alive to old ages [19][20][21].…”