Niyogi Lab Research

False-color image of photosystem II efficiency in colonies of Chlamydomonas mutants that are unable to do photosynthesis. Photo credit: Robert Calderon

Oxygenic photosynthesis is the biological process that converts solar energy, carbon dioxide, and water into biomass and oxygen, and it is the defining metabolism of plants, algae, and cyanobacteria. Research in the Niyogi lab is focused on the regulation of photosynthesis and photoprotection, assembly and dynamics of photosynthetic membranes, and improvement of photosynthesis. 

 


 

Regulation of Photosynthetic Light Harvesting

In nature, algae and plants experience a large dynamic range of light intensities, and they need to regulate photosynthesis to balance the absorption and utilization of light energy. In saturating light, photosynthetic light harvesting is regulated by a suite of non-photochemical quenching (NPQ) mechanisms that safely dissipate excess absorbed light energy as heat. The major goal of our NPQ research is to understand the mechanisms of different NPQ components in diverse photosynthetic organisms.

Singlet Oxygen Signaling

Singlet oxygen is a major type of reactive oxygen species that is generated in excess light by energy transfer from excited chlorophylls. We discovered that Chlamydomonas exhibits an acclimation response to singlet oxygen stress that enables cells to survive singlet oxygen levels that would otherwise be lethal. This response involves retrograde signaling from the chloroplast to the nucleus to regulate expression of nuclear genes, and we have taken a genetic approach to investigate this signaling pathway.

Assembly and Dynamics of Photosynthetic Membranes

The light-dependent reactions of oxygenic photosynthesis in algae and plants are catalyzed by a series of thylakoid membrane protein complexes in chloroplasts. Although high-resolution structures are now available for the major complexes, a thorough understanding of photosynthetic membrane biogenesis, regulation, and repair is lacking. We are using genetics, advanced imaging, and modeling to investigate these dynamic processes.

Improving Photosynthesis

Increasing the efficiency of converting absorbed light energy into biomass energy is critical for meeting future needs for food and fuel. Energy losses occur at several steps in photosynthetic energy conversion, resulting in an overall, theoretical maximum efficiency of converting total sunlight into biomass of ~5-6%. However, the actual efficiencies of crop plants are substantially less than the theoretical efficiencies, leaving considerable room for improvement.

Chlamydomonas

green alga Chlamydomonas
The unicellular green alga Chlamydomonas reinhardtii is one of our favorite model organisms for elucidating the detailed functions of genes involved in photosynthesis and photoprotection.

Chromochloris

Chromochloris zofingiensis is an emerging model organism for studying triacylglycerol (TAG) and secondary carotenoid (astaxanthin) accumulation, photoprotection, regulation of metabolism, and cell biology of green algae.

Nannochloropsis

Nannochloropsis oceanica is an emerging model organism for photosynthetic Stramenopiles (heterokonts).