Why does the sunflower follow the sun?

The sunflower's ability to follow the sun's path from east to west throughout the day and reorient itself to the east before the next sunrise depends on a mechanism unknown until today.

This mechanism has been recently discovered and published in the journal "PLOS Biology" by Stacy Harmer and her colleagues at the University of California, Davis. Because the plant is rooted in one place, it cannot get up and move when neighbors block the light or germinate in a shady location. Instead, they depend of growth or lengthening to move towards the light.

What is the complete cycle of heliotropism?

When dawn comes, the heads of the sunflowers will face east, ready to welcome the dawn. As the sun moves across the sky during the day, the head of this flower follows it. Finally, when the sun sets towards the west, the head will end up in this position. At night, it will gradually turn eastward, ready to receive sunlight again.

Young plants need to control sunlight to obtain optimal energy to grow. This is called photosynthesis and is the process of collecting sunlight and converting it into energy and food for the plant. Lack of sunlight weakens plants.

When sunflowers mature, they stop following the sun. This is mainly because their overall growth rate slows down when they reach their peak. As a flower ages, its biological clock responds more positively to morning sunlight than midday sunlight. This means your internal clock will adjust and focus on appropriate sunlight.

The ability of sunflowers to follow the sun

Until now, it was unclear whether sunflowers' ability to follow the sun, known as heliotropism, was a form of phototropism involving the same receptors and hormones. To investigate this question, the authors compared the gene activity patterns of blue light-sensitive sunflowers in the laboratory with the gene activity patterns of sun-sensitive sunflowers in the field.

There are several molecular systems that facilitate these reactions, the most famous of which is phototropism. In this system, blue light shining unevenly on seedlings is detected by proteins called phototropins, which cause plant hormones to redistribute and eventually cause the growing tip to bend toward the light.

Surprisingly, a small number of rapidly activating genes responsible for phototropic bending in the laboratory showed significant differences in their activity in response to solar motion.

In addition to these genes, the researchers also found changes in other light response systems, including the shadow avoidance system, which detects far-red light (shadow enrichment), activated for the first time on the west side of the sunflower stem. early in the day, when the sun is in the east.

However, to make the picture even more complex, they showed that limiting red light, far-red light, or blue light had little effect on sunflowers' ability to follow the sun. This suggests that many systems can coordinate their actions to produce a heliotropic response, even if one or more light activators are missing.

"What we discovered when we studied how sunflowers move with the sun every day continues to surprise us"Harmer admitted in a statement."In this study, we report that sunflowers use distinct molecular pathways to initiate and maintain pursuit movements, and photoreceptors, best known for inducing plant curvature, appear to play a minor role in this unusual process.".

Sunflowers have fascinated humans for many years and still attract our attention. atención because these colorful flowers have a circadian rhythm similar to the human biological clock.


With information of: https://www.europapress.es/