White oak (Quercus fabri Hance) regenerated stump sprouts show few senescence symptoms during 40 years of growth in a natural forest

The relationship between physiological age of parental trees and lifespan of clonal offspring is unclear. White oak (Quercus fabri Hance) has a high sprouting capability after harvest, with the regenerated sprouts being typical clonal individuals. To determine whether regenerated sprouts undergo rapid senescence compared with the parent, the senescence levels of 5-, 10-, 20- and 40-year-old regenerated stump sprouts in a natural forest were evaluated. The antioxidative abilities and transcriptomes in these leaves and shoots were compared.

Older regenerated sprouts still had robust antioxidative systems, with 40-year-old sprouts having lower peroxidation product levels but similar antioxidative enzyme activity levels compared with 5-year-old sprouts. Older leaves had greater transcriptional activities in pathways related to cell growth and division than younger leaves. However, older sprouts had some unhealthy characteristics, such as increased base excision repair levels and upregulated phagosome, proteasome and glycerophospholipid metabolism pathways in 40-year-old leaves, which indicates that DNA damage and tissue remodeling occurred more frequently than in younger leaves. Additionally, plant-pathogen interactions and MAPK signals pathways were upregulated in older shoots, which indicates that older shoots suffered from more pathogen-related biotic stress.

The 40-year-old sprouts still had the same vitality level as the 5-year-old sprouts, although the former had some unhealthy characteristics. We conclude that during their first 40 years of growth, regenerated stump sprouts do not begin to senesce, and that physiological age of parental trees does not significantly affect the lifespan of its clonal offspring.