Spruce trees remember their embryonic temperature for over a decade
Yakovlev IA, Viejo M, Tengs T, Olsen JE, Fossdal CG
Climate Adaptation
If you've ever wondered why two trees of the same species leaf out on different schedules in your yard, this shows the answer can be set before the tree even germinates, by the temperature its embryo experienced, and that memory can last well over a decade.
Scientists grew Norway spruce trees from embryos that developed in either warmer or cooler conditions, then planted all the trees together in the same location for 14 years. The trees still behaved differently, budding at different times, and the researchers found the reason written into the trees' DNA: chemical tags called methylation marks that formed during the embryo stage stuck around for over a decade in specific genes tied to seasonal timing. It's a bit like the tree's earliest environment leaving a sticky note on certain genes that keeps getting read year after year.
Key Findings
Targeted bisulfite sequencing across 2,744 genes revealed stable CG-context methylation differences that clearly separated warm-embryo (WE) from cool-embryo (CE) epitype trees at 14 years old
30 genes showed stable CG and CHG methylation marks in their promoter regions, including two ARGONAUTE genes and four others that held consistent marks across all seasonal time points
Methylation patterns were highly dynamic across the annual cycle in all cytosine contexts, suggesting circannual clocks influence methylation, while CHH-context marks showed no stability, unlike the more heritable CG and CHG marks
chevron_right Technical Summary
Norway spruce trees grown from seeds started in warm versus cool conditions carry a lasting molecular memory of that early temperature, encoded in chemical marks on their DNA that persist over 14 years and still affect when the trees bud each spring.
Abstract Preview
Original paper
Stable and temporally shifted DNA methylation differences between 14-year-old Norway spruce epitypes under common garden conditions.
Dynamic DNA methylation differences between epitypes throughout the annual cycle, circannual clocks affect methylation levels, stable methylation marks in the promoters of 30 candidate genes, embry...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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Picea abies, the Norway spruce or European spruce, is a species of spruce native to Northern, Central and Eastern Europe.