Chemicals in wildfire smoke enhance the light responsiveness of seedlings of the model plant Arabidopsis thaliana.
Researchers already knew that chemicals called karrikins, which are found in such smoke, can promote seed germination. Steven Smith and his colleagues at the University of Western Australia in Perth have now found that a karrikin known as KAR1 also affects the expression of several light-responsive genes. Treating A. thaliana seedlings with KAR1 increased their responses to light by promoting the growth of seedling leaves while suppressing growth in the seedling's embryonic stem, called the hypocotyl.
This effect on the hypocotyl was diminished in plants with a mutation in the HY5 gene, which regulates light responses. The results suggest a new way in which plants respond to karrikins to adapt to the drastic environmental changes caused by fire.
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Plant biology: Seeking enlightenment. Nature 464, 817 (2010). https://doi.org/10.1038/464817b