2023-11-01 09:27:55
Scientists admit they are powerless in the face of the mystery of how sunflowers catch light. The researchers found that these plants do not use normal processes to follow the sun’s movement across the sky.
With their bright yellow manes and sturdy stems, sunflowers may seem like a simple summer treat, writes The Guardian. But researchers say these plants have become surprisingly mysterious after scientists discovered they don’t use normal processes to track the sun’s movement across the sky.
During the day, sunflowers follow the path of the sun overhead—a process known as heliotropism—with their heads gradually tilting westward as a result of the elongation of cells on the eastern side of the stem.
At night, the cells on the opposite side of the stems elongate, causing the heads to reorient to the east.
However, researchers say the processes behind tracking solar activity have turned out to be an unexpected mystery.
“Many of our results were different from what we expected,” admits Professor Stacey Harmer, study author from the University of California, Davis.
Many plants grow towards the light source – this is because when blue light receptors called phototropins are activated on the illuminated side of the stem, they cause hormones called auxins to concentrate on the other, “dark” side.
These auxins stimulate cell elongation, causing the stem to bend toward the light.
While new research suggests this mechanism explains how sunflowers lean toward artificial light indoors, it doesn’t seem to explain how sunflowers naturally track the path of the sun.
In a paper published in the journal Plos Biology, Professor Harmer and colleagues reported that they first analyzed which genes were turned on in the stems of sunflowers grown indoors when artificial blue light was shone from one direction.
The results show that genes related to phototropins were primarily turned on on the light side of the stem, while genes related to auxins and cell growth were turned on on the shadow side, suggesting that sunflowers grown indoors turn to blue light through normal processes.
But when the team turned to the stems of outdoor sunflowers, they discovered something different. The eastern side of the stem, the side exposed to sunlight, and the western side, the side exposed to shade, showed little difference in which of these genes were turned on.
The researchers then tried blocking blue and ultraviolet or red and far-red light on their own, but found that neither attempt alone affected the heliotropism of plants outdoors, suggesting that multiple light transmission pathways are likely involved simultaneously. alarms.
On the other hand, the team found that when sunflowers grown indoors were moved outdoors, the plants immediately began to follow the sun.
However, their stems had a different set of genes turned on on the first day outdoors compared to when they were indoors or the subsequent days outdoors, suggesting that some kind of adaptation mechanism was at play.
Professor Harmer notes that the work suggests that results obtained in controlled conditions do not necessarily reflect what happens in the wild. “Our results show that both sun tracking and phototropism in real-world environments are much more complex than we expected,” she said.
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