The origin and evolution of auxin as a plant signaling molecule.
Hernandez-Garcia J, Weijers D
Plant Signaling
Every time you pinch back a leggy seedling or stake a climbing vine, auxin is the signal your plant uses to decide where to grow next — and understanding where that signal came from explains why plants respond to pruning, light, and wounding the way they do.
Auxin is a tiny chemical that plants use like a text message to tell different parts of the plant what to do — grow here, stop growing there, make a root, drop this leaf. What's surprising is that this same chemical exists in bacteria, fungi, and animals too, but only plants evolved the machinery to 'listen' to it as an internal command. This study pieces together how a handful of ancient proteins gradually got repurposed to build that listening system, turning an outside environmental cue into an inside plant decision.
Key Findings
Auxin is not unique to plants — it is found across all domains of life (bacteria, fungi, animals), but plants uniquely evolved an intracellular system to use it as a developmental signal.
A small number of pre-existing proteins were co-opted and coordinated to assemble the auxin perception and response system, meaning the system arose from repurposing rather than invention from scratch.
The capacity to synthesize auxin internally converted what was once an environmental/ecological signal into a tightly controlled endogenous (inside-the-plant) hormone.
chevron_right Technical Summary
A chemical called auxin controls how plants grow — bending toward light, growing roots, dropping leaves — and scientists have now traced how this molecule went from being a common compound found across all living things to becoming a master switch inside plants.
Abstract Preview
The plant signaling molecule auxin is key to plant growth and development, and has been connected to numerous processes. Yet, auxin is by no means a plant-specific compound, but is found ubiquitous...
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