Light-regulated responses to abiotic and biotic stress in marine microalgae

For marine photoautotrophs, light is a key environmental signal controlling a range of physiological and adaptive processes. In this talk, I will present two projects in our lab that focus on the role of light and photosynthesis on the physiology of marine phytoplankton.

In the coastal diatom, Thalassiosira pseudonana, we have identified a protein that mediates photosynthetic responses under iron (Fe) limitation and high light. TpDSP1 is a Ca2+-binding, plastid-localized protein that, when over-expressed in T. pseudonana, significantly increases fitness under Fe limitation by increasing growth rates, photosynthetic efficiency, and cyclic electron flow around photosystem I. However, TpDSP1 also conferred a physiological disadvantage whereby over-expression led to increased sensitivity to high light, forcing cells to walk an ecological ‘tightrope’ through the regulation of this protein.

In the second part of my talk, I will discuss the role of light in mediating host-virus interactions. Microalgal viruses are inherently dependent on light and host photosynthesis given the need for host-derived resources. However, the extent of this dependence and the role light plays in structuring infection in the environment has not been comprehensively investigated. We are using the model algal host, Emiliania huxleyi a cosmopolitan coccolithophore capable of forming massive annual blooms in the North Atlantic, and its associated Coccolithoviruses (EhVs), giant nucleocytoplasmic double-stranded DNA-containing viruses, to characterize the role of light in viral infection dynamics.