Poplar trees reroute a growth hormone to build stronger wood
Xiang D, Ran L, Li Y, Zong L, Li B
Plant Signaling
The way a leaning tree in your yard thickens up on one side to right itself is driven by this exact hormone-routing switch, so understanding it helps explain why storm-bent trees often recover and grow sturdier.
Trees build new wood every year using a thin layer of cells called the cambium, and a plant hormone called auxin tells those cells when and where to grow. Researchers found a specific transport protein in poplar trees that acts like a one-way valve, pushing auxin to just the right cells, and when a tree gets tilted by wind or gravity, this same protein switches direction to help the tree grow extra-strong 'tension wood' on one side to straighten itself back up.
Key Findings
Two redundant PIN3 genes in Populus tomentosa were knocked out using CRISPR, and losing them severely impaired cambial cell division, wood formation, and the tree's ability to build gravity-triggered tension wood
PIN3 proteins show distinct, cell-type-specific positioning: they sit at the base of phloem cells (driving auxin downward) but on the outer side of endodermal cells
When stems were tilted to simulate gravity stress, PIN3 in endodermal cells physically relocated to align with the new gravity direction, matching where tension wood formed
chevron_right Technical Summary
Scientists discovered how poplar trees steer a growth hormone to the exact cells that build wood, and how that same system lets trees reinforce their trunks when leaning or exposed to wind.
Abstract Preview
Original paper
Cell-type-specific PIN-FORMED 3-mediated polar auxin transport regulates cambial activity and tension wood formation in Populus tomentosa.
Auxin is a central regulator of tree secondary growth and forms maxima in the vascular cambium, yet how these maxima are established remains elusive. Here, we functionally characterized two redunda...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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Populus is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar, aspen, and cottonwood.