Algae 'see' a wide range of light

May 01, 2014
Freshwater-dwelling algae like these are among those able to sense a surprisingly wide spectrum of light. Credit: J. Clark Lagarias, UC Davis

(Phys.org) —Aquatic algae can sense an unexpectedly wide range of color, allowing them to sense and adapt to changing light conditions in lakes and oceans. The study by researchers at UC Davis was published earlier this year in the journal Proceedings of the National Academy of Sciences.

Phytochromes are the eyes of a plant, allowing it to detect changes in the color, intensity, and quality of so that the plant can react and adapt. "They control all aspects of a plant's life," said Professor Clark Lagarias, senior author on the study. Typically about 20 percent of a plant's genes are regulated by phytochromes, he said. Phytochromes use bilin pigments that are structurally related to chlorophyll, the molecule that plants use to harvest light and use it to turn carbon dioxide and water into food.

Lagarias' laboratory in the Department of Molecular and Cellular Biology at UC Davis studies these phytochromes and their properties. Phytochromes from , Lagarias said, respond to —plants absorb red and reflect green light, which is why they look green. Red light does not penetrate far into water, and some marine and shore-dwelling lack phytochrome genes. But others do not, so Lagarias and colleagues looked at the properties of phytochromes from a variety of algae. They found that phytochromes from algae, unlike those of land plants, are able to perceive light across the visible spectrum—blue, green, yellow, orange, red and far-red.

Algae 'see' a wide range of light
Cyanophora paradoxa, one of the algae with newly discovered phytochromes.

This broad spectral coverage likely helps algae make use of whatever light they can in the ocean, Lagarias said—whether adjusting their light-harvesting chemistry for changing conditions, or rising and sinking in the water column as light levels at the surface change. Because different colors of light penetrate to different depths in water, algae face challenges in light harvesting that land plants do not. This work from the Lagarias lab shows one way that algae can rise to the occasion.

This video is not supported by your browser at this time.
Clark Lagarias talks about phytochromes, algae and light detection.

Phytochromes themselves have a long evolutionary history and likely arose from the interaction between oxygen and bilins, pigment molecules closely tied to chlorophyll and the oxygen-carrying heme pigment in hemoglobin, Lagarias said. The ancestral form appears to be sensitive to red light, similar to phytochromes of modern land plants. But between the origin and today, phytochromes went through a stage of massive diversity when they could detect a much wider range of wavelengths.

"It's a molecule that has been there and back again," Lagarias said.

The broad color palette of algal bilin-based light sensors found in nature.

The discoveries help researchers better understand the role of light and response to light in shaping ecology, as well as a model for how living cells react to light. They could also help in breeding of aquatic crops that could take advantage of different light conditions.

Explore further: New lab technique reveals structure and function of proteins critical in DNA repair

More information: Paper: www.pnas.org/content/111/10/3871.full

Related Stories

Marine algae can sense the rainbow

Feb 24, 2014

A new study published in Proceedings of the National Academy of Sciences has shown for the first time that several types of aquatic algae can detect orange, green and blue light.

Ferns borrowed genes to flourish in low light

Apr 14, 2014

During the age of the dinosaurs, the arrival of flowering plants as competitors could have spelled doom for the ancient fern lineage. Instead, ferns diversified and flourished under the new canopy—using ...

Recommended for you

The mechanics of life

Apr 16, 2015

An interdisciplinary research team formed by Otger Campàs, assistant professor in the Department of Mechanical Engineering at the University of California, Santa Barbara (UCSB), and colleague Jérome Gros, ...

New transitional stem cells discovered

Apr 16, 2015

Pre-eclampsia is a disease that affects 5 to 8 percent of pregnancies in America. Complications from this disease can lead to emergency cesarean sections early in pregnancies to save the lives of the infants and mothers. ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.