Trees use a hormone switch to soften wood under stress
Dai X, Zhang W, Wang H, Liu J, Zhao J
Plant Signaling
The leaning trunk or wind-bent branch in your yard is quietly rewriting its own wood chemistry in real time, dialing lignin production up or down to keep from snapping.
When a tree gets pushed around by wind or grows at a tilt, it builds a special kind of wood called tension wood that has less of the stiff stuff called lignin, making that wood more flexible. Researchers found the tree uses a growth hormone to turn on a protein that acts like a dimmer switch, physically changing how tightly certain genes are packaged so the lignin-making genes get quieted down. It's a clever example of a plant using its own hormones to remodel its body's building materials on the fly.
Key Findings
Gibberellin (GA) hormone accumulation during tension wood formation activates the transcription factor PtrLBD39, which represses lignin biosynthesis genes.
PtrLBD39 binds a newly identified DNA motif (TCACGB) in the promoters of lignin genes PtrHCT1 and PtrHCT6, recruiting histone deacetylases PtrHDA6-A and PtrHDA6-B to silence them epigenetically.
CRISPR knockout of PtrLBD39 increased lignin content, while targeted activation of PtrLBD39 or overexpression of PtrHDA6-A reduced lignin, confirming the gene's causal role in wood composition.
chevron_right Technical Summary
Scientists discovered how trees decide to make less of the stiff material lignin when growing specialized 'tension wood' to brace against wind and gravity. A hormone-triggered genetic switch essentially dims the genes responsible for lignin production, helping explain how trees physically adapt their wood to mechanical stress.
Abstract Preview
Original paper
Gibberellin-mediated PtrLBD39-PtrHDA6-PtrHCT epigenetic path regulates lignin biosynthesis during tension wood formation in Populus trichocarpa.
Tension wood (TW) is a specialized xylem tissue formed in angiosperm trees to counteract mechanical stresses. Increased phytohormones, particularly gibberellins (GAs), and decreased lignin depositi...
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