Old trees may stay healthy by preventing senescence and maintaining robust resistance to external stress, a study finds. Trees can live for centuries or even millennia, but the molecular and metabolic mechanisms underlying their long lifespans are unclear. Richard Dixon, Jinxing Lin, and colleagues examined age-related changes in the vascular cambium, the main growth tissue in the stems and roots, of 15- to 667-year-old Ginkgo biloba trees. Increasing age was not accompanied by a significant decrease in leaf area, photosynthetic efficiency, seed germination rate, or basal area increment, which is a reliable indicator of tree growth based on tree ring analysis. RNA sequencing of the vascular cambium revealed an age-related decline in the expression of genes involved in cell division, expansion, and differentiation--processes important for vascular tissue growth. However, these changes were not accompanied by a significant increase in the expression of genes related to senescence, which is the final developmental stage. Moreover, the vascular cambium of young and old trees displayed similar expression levels for genes associated with the biosynthesis of protective metabolites called flavonoids, as well as other resistance genes involved in defending against stress related to factors such as pathogens or drought. According to the authors, the findings suggest that old trees may stay healthy by preventing senescence and maintaining robust resistance to external stress.
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Article #19-16548: "Multifeature analyses of vascular cambial cells reveal longevity mechanisms in old Ginkgo biloba trees," by Li Wang et al.
MEDIA CONTACTS: Richard Dixon, University of North Texas, Denton, TX; tel: 940-565-2308; e-mail: richard.dixon@unt.edu; Jinxing Lin, Beijing Forestry University, Beijing, CHINA; e-mail: linjx@ibcas.ac.cn
Journal
Proceedings of the National Academy of Sciences