Pigments responsible for Euglena’s eyespot apparatus identified

January 30, 2023

New findings on the light perceptive organelle and pigment synthesis of microalgae

The joint research team from RIKEN Baton Zone Program, RIKEN CSRS, and RIKEN Center for Advanced Photonics analyzed mutants of Euglena gracilis (Euglena), a member of Euglenophyta microalgae, with an altered composition of pigments (carotenoids), using genome editing to identify carotenoids required for functional eyespot apparatus that senses light in Euglena.

In this study, the research team used a highly efficient genome editing technique to engineer Euglena strains that lack one or both of the two genes related to carotenoid synthesis, CYP97H1 and CYP97F2. Analyzing the eyespot formation, compositions of carotenoids, and motility toward/away from light, they demonstrated that zeaxanthin, a type of carotenoids, is essential for the functional eyespot formation and that CYP97H1 and CYP97F2 are involved in its synthesis in Euglena. Among microalgae, Chlamydomonas, a member of green algae, is known to accumulate another type of carotenoid in its eyespot, suggesting that that the light recognition mechanism may vary between Euglenophyta and Chlorophyta.

The results of this study have provided new insights into the function of carotenoids and the pathway for carotenoid biosynthesis in Euglena. These findings would contribute to further research on the production of valuable carotenoids.

Original article
Plant Physiology doi:10.1093/plphys/kiad001
S. Tamaki, K. Ozasa, T. Nomura, M. Ishikawa, K. Yamada, K. Suzuki, Keiichi Mochida,
"Zeaxanthin is required for eyespot formation and phototaxis in Euglena gracilis".
Keiichi Mochida
Team Leader
Bioproductivity Informatics Research Team