Antagonism between blue- and red-light signaling controls thallus flatness in Marchantia polymorpha.
Roetzer J, Asper B, Meir Z, Edelbacher N, Mérai Z
Plant Signaling
Every time your houseplants lean or droop toward a window, the same tug-of-war between red and blue light wavelengths is happening — this research reveals the molecular switch that keeps plants growing level when light is balanced.
Liverworts are ancient, simple plants that grow as flat, ribbon-like sheets along the ground. Researchers found that red light tells the liverwort to curl downward while blue light tells it to curl upward — like two hands pulling in opposite directions. In normal white sunlight, which contains both colors, the two signals balance perfectly and the plant stays flat.
Key Findings
Red-light signaling causes downward curling (epinasty) and blue-light signaling causes upward curling (hyponasty); together in white light they balance to produce flat growth.
Plants with a disabled blue-light receptor curled down; plants with a disabled red-light receptor curled up — confirming each receptor drives the opposing response.
Two BBX transcription factor genes act antagonistically downstream of light: losing both BBX1 and BBX5 together restored flat growth, proving they are key mediators of this light-balancing system.
chevron_right Technical Summary
Scientists discovered that red light and blue light give opposite growth instructions to liverworts, pulling the plant body in competing directions. When both colors are present — as in natural sunlight — the signals cancel out, producing a perfectly flat plant.
Abstract Preview
The growth orientation of the Marchantia polymorpha thallus-a system of dorsiventralized, indeterminate axes-is modulated by light. We show that red and blue light act antagonistically to control t...
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Species Mentioned
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Marchantia polymorpha is a species of large thalloid liverwort in the class Marchantiopsida. M. polymorpha is highly variable in appearance and contains several subspecies. This species is dioicous, having separate male and female plants. M. polymorpha has a wide distribution and is found worldwi...