June 16, 2021
Adaptation of green picoplankton widely living in the ocean to different light environments
A joint study group including RIKEN CSRS, National Institute for Environmental Studies, Shizuoka University, Japan Fisheries Research and Education Agency, the University of Tokyo, and Ochanomizu University discovered a new photoreceptor which detects three types of light from green picoplankton distributed widely in the ocean by analyzing marine metagenome data obtained Sendai Bay, Japan, and the western subarctic Pacific Ocean from 2012 to 2014.
Most of green picoplankton need light to survive. Among the constituents of sunlight, blue light penetrates deeper in the ocean than red light. Therefore, photoreceptors which detect light of different wavelengths are indispensable for green picoplankton living at different depths of the ocean.
The joint group analyzed marine metagenome data using the gene sequence of a blue light receptor, cryptochrome, as a query, and found a chimeric gene composed of a cryptochrome and a red-light receptor, phytochrome. The protein derived from this gene is named “dualchrome”. The researchers found that dualchromes detect blue, orange and far-red light, and are possessed by Pycnococcus, one of prasinophytes, oceanic plankton, and its relatives. In addition, they sequenced the whole genome of Pycnococcus, and elucidated part of the basis of how these algae have adapted to various light environments from the lower part of the marine euphotic zone where light hardly reaches up to the surface of the ocean.
This finding is considered to contribute to understanding the photoreceptive mechanism and evolution of photoreceptors of green picoplankton in the ocean.
Nature Communications doi:10.1038/s41467-021-23741-5
Y. Makita, S. Suzuki, K. Fushimi, S. Shimada, A. Suehisa, M. Hirata, T. Kuriyama, Y. Kurihara, H. Hamasaki, E. Okubo-Kurihara, K. Yoshitake, T. Watanabe, M. Sakuta, T. Gojobori, T. Sakami, R. Narikawa, H. Yamaguchi, M. Kawachi, M. Matsui,
"Identification of a dual orange/far-red and blue light photoreceptor from an oceanic green picoplankton".
Minami Matsui; Group Director
Yuko Makita; Senior Scientist
Setsuko Shimada; Research Scientist
Synthetic Genomics Research Group