Plants rely on their ability to sense light for survival. But unlike animals, plants don’t have eyes full of photoreceptors to capture and convey messages from visual stimuli. Instead, photoreceptors that detect different wavelengths of light are found in cells throughout the plant, allowing plants to regulate their lifecycles and adjust to environmental conditions.
Phytochromes are one of the main collections of photoreceptors. They sense red and far-red light as well as temperature. But even though they were identified 70 years ago — and they are important for many aspects of plant growth and development critical to agriculture — it has remained unclear how phytochromes work.
Now, scientists at Washington University in St. Louis and the Van Andel Institute (VAI) have determined the molecular structure of one of these vital photoreceptors — for an isoform known as phytochrome B or PhyB — revealing a wholly different structure than previously known. The findings, published March 30 in Nature, have many implications for agricultural and “green” bioengineering practices.
“Plant phytochromes are amazing molecular machines that perceive light and temperature through very specific conformational changes,” said Richard Vierstra, the George and Charmaine Mallinckrodt Professor of Biology in Arts & Sciences at Washington University and co-corresponding author of the study.
“The PhyB structure that we uncovered in this study tells us something that we never expected,” Vierstra said. “We learned that plant phytochromes are topologically complex, asymmetric and look nothing like their microbial relatives. And that they likely work in a wholly unexpected way.”
