Yale Study Pinpoints How Plants Adjust To And Grow In Various Lighting Conditions

"Our study is the first step in understanding the biochemical mechanism of this process in plants," said Xing-Wang Deng, associate professor and director of graduate studies in Yale's Department of Molecular, Cell and Developmental Biology. "There's a key developmental switch that tells plants what to do in different lighting conditions. All the components in this switch are also present in humans and our work could provide clues to understanding conditions like winter depression and jet lag."

Published in the May 25 issue of Nature, Deng and his team showed that plants have a sophisticated way of adapting to seasonal changes and lighting environment. They grow differently depending on the direction, light-dark period, intensity and the wavelength-color of the light. "They don't necessarily grow faster or slower, Deng said. "They just grow in the best way possible to harvest whatever sunlight is provided to them."

Using Arabidopsis, a weed-like model for plant research, Deng's team grew seedlings under lights with varying intensities and wavelengths, resulting in drastically diverse growth patterns. In higher intensity light conditions, the Arabidopsis grew shorter, but stronger and greener. In darker conditions, they grew taller, but with thinner stems, and yellow leaves.

The different growth patterns are due to the breakdown of key control proteins in the plants, the team found. Multiple photoreceptors in the seedlings perceive light signals and send this information to two protein components-COP1 and HY5, which then regulate seedling development. There are over a dozen different components involved in the process. Deng said the findings are the first clue to understanding how the entire mechanism works at the biochemical level.

"We have found the key to how a plant can sense its light environment and modify its development to optimize photosynthesis, which turns light energy into chemical energy," said Deng. "The immediate application would be for agriculture. Farmers can alter crops so they will thrive in less favorable light conditions. This finding can also be used to make greenhouse plants grow much stronger and healthier in early spring, when light is not as abundant."

Deng's research team in Yale's Department of Molecular, Cellular and Developmental Biology included Mark T. Osterlund, Ph.D. student; Christian S. Hardtke, postdoctoral fellow and Ning Wei, associate research scientist.