LEAPS-MPS: Elucidating the Properties and Role of a Stress-induced Fluorescence State in Photosynthetic Diatoms

In this project, funded by the MPS-LEAPS (Launching Early-Career Academic Pathways) Program and managed by the Division of Chemistry (CHE), Professor Massey and her students at Southwestern University will perform studies to investigate the effects of native environment and external stressors on light harvesting in diatoms, a type of marine algae that contribute up to 25% of global photosynthetic carbon fixation. The diatom Phaeodactylum tricornutum (P. tricornutum) emits from a lower energy fluorescence state, F710, when grown under red light or other light stress conditions. Professor Massey and her students will use fluorescence spectroscopy to study how other environmental and stress conditions affect emission from this low energy state. Their studies will increase understanding of how diatoms acclimate to robustly harvest solar energy under stress. These projects will train undergraduate researchers in both the research lab and a Course-Based Undergraduate Research Experience (CURE) lab, preparing them to be successful research scientists. Additionally, local K-12 students will be engaged through science outreach, inspiring future generations to pursue STEM careers. Professor Massey and her students will employ steady-state and time-resolved fluorescence spectroscopies to examine the effects of environment and stress on light-harvesting dynamics in P. tricornutum at physiological and cryogenic temperatures. These experiments will provide insight into the physical properties and dynamics of the F710 state induced by different stress conditions. F710 emission induced by red light in P. tricornutum has been attributed to oligomers of the Lhcf15 protein. It is unknown whether this same protein is responsible for F710 emission induced by other stressors. Experiments using mutant constructs of P. tricornutum will generate a new understanding of the origin of F710 emission, informing on whether this fluorescence signal is a single generalized stress response or a signal resulting from a spectrally overlapped collection of different states. Insight into mechanisms of acclimation to changing environmental conditions in P. tricornutum will provide insight to better engineer diatom cell factories under varied and changing ecological conditions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.