Sunflowers are famous for turning their heads to follow the sun as it moves across the sky.
It’s a beautiful sight, but how do they actually do it?
Scientists from the University of California, Davis, have uncovered some surprising new details about this process. Their findings were published in the journal PLOS Biology.
Professor Stacey Harmer, a plant biology expert at UC Davis, and the main researcher of the study, shared their surprise.
They discovered that sunflowers have a unique way to ‘see’ and follow the sun that is different from what scientists used to believe.
First, let’s understand the basics. Plants have a feature called phototropism. It’s their ability to grow towards a light source.
Scientists used to think that the way sunflowers followed the sun, called heliotropism, was because of phototropism.
This was thought to be controlled by a molecule named phototropin that responds to blue light.
Here’s a cool fact: Sunflowers turn their heads by growing a bit more on one side during the day and another side at night.
So, during the day, the east side of the sunflower stem grows a bit more, making the flower face west. At night, the west side grows more, making the flower turn back east.
Professor Harmer and her team had earlier found out how sunflowers use their inner “body clocks” to get ready for sunrise. This clock also helps the sunflower know when pollinating insects, like bees, are likely to visit.
In their new research, the team studied sunflowers in two places: inside a lab and outside under the sun. They wanted to see which genes the sunflowers were using in both conditions.
Here’s where it gets interesting! The indoor sunflowers, which grew straight towards the lab light, used genes related to phototropin. But the outdoor sunflowers, which turned with the sun, showed a different set of active genes. Also, there wasn’t any change in phototropin in the outdoor plants.
But what does this mean? Well, the researchers haven’t found the exact genes responsible for the sun-following behavior of outdoor sunflowers. Harmer mentioned, “We know it’s not the phototropin pathway we first thought, but we’re still searching for the real answer.”
They also tried an experiment by blocking different colors of light (like blue, ultraviolet, red) to see the sunflower’s reaction. The result? The sunflowers kept following the sun. This suggests that there might be several ways the plant detects light, and they’re all working together.
Another fascinating discovery was how quickly sunflowers can adapt. Sunflowers that were initially grown inside the lab were taken outside. Guess what? On the very first day, they started following the sun!
This change in behavior was linked to a sudden burst of gene activity on the side of the plant that was in shade. But this burst didn’t happen again the next days. It looks like the sunflowers quickly “rewire” themselves to adjust to new conditions.
Professor Harmer believes this study teaches us more than just about sunflowers. She highlights an essential point: what we observe in controlled settings, like labs, might not always match what happens in nature.
She says, “Things that you define in a controlled environment may not work out in the real world.”
In a nutshell, sunflowers have a special, mysterious way of tracking the sun, and there’s still much to discover about it. This research not only gives us insight into the incredible world of plants but also reminds us of the wonders of nature all around us.
Follow us on Twitter for more articles about this topic.
