The discovery was made from a research collaboration between the Universities of Bristol and Essex. Considering why blue begonias survive at the level of a forest floor, where there is little sunlight, has helped to unlock a process that could lead to improved energy efficiency on an industrial scale.
These plants, which are also common houseplants, work at the nano-level through the use of photonics. This process enables the plant to create structures in their leaves that help them to harvest light for photosynthesis. One reason for the popularity of begonias as houseplants is because the plants do not require direct sunlight.
Begonia is a genus of perennial flowering plants in the family Begoniaceae, and there are almost 2,000 species worldwide. Most species come from tropical regions. Within the variety, it is the blue begonia that has sparked interest from physicists as well as biologists.
Biologist Dr. Heather Whitney, the lead researcher, found that the leaves of the ‘blue’ begonia only developed the characterisitc blue sheen once the plant is placed in near-dark conditions. Furthermore, once the plant is placed back in bright light the sheen slowly disappears.
Looking into this further, the researchers discovered that individual chloroplasts in these leaves reflected blue light brightly, much like a mirror. It was found there was a significant difference between the ‘blue’ chloroplasts found in the begonias (termed ‘iridoplasts’) compared with chloroplasts present in other plants. The differences related to the arrangement of the inner structure and the thickness, at the nano-level.
Incredibly, using electron microscopy it was found that these structures resembled the artificial structures used to manufacture miniature lasers and other photonic structures that control the flow of light. Applying knowledge of these lasers led to the further discovery that the blue begonia chloroplasts absorb most of the blue light from sunlight, leaving only green light filtering through to the begonias on the ground.
The final piece in the jigsaw came when researchers at the University of Essex studied the rate of photosynthesis in these iridoplasts compared to normal chloroplasts and found that in very low light levels, the iridoplasts performed better.
The way the plants work can offer clues for improving artificial photonic structures, by more efficiently harvesting parts of the electromagnetic spectrum that is not absorbed. The discovery about how blue begonias work marks the start of a new realm of energy research and could one day lead to more efficient electronics.
The research has been published in the journal Nature Plants, and it is titled “Photonic multilayer structure of Begonia chloroplasts enhances photosynthetic efficiency.”
