Biosciences Area

Regulation of Algal Photosynthesis and Metabolism

The unicellular green alga Chromochloris zofingiensis has the ability to shift metabolic modes from photoautotrophic (synthesizing food using light as energy source) to heterotrophic (obtaining food and energy from exogenous sources) in response to carbon source availability in the light. It also has the capacity—under certain conditions—to produce high amounts of commercially relevant bioproducts: notably, the ketocarotenoid astaxanthin, used in feed, cosmetics, and as a nutraceutical, and triacylglycerol (TAG) biofuel precursors.

Understanding how photosynthesis and metabolism are regulated in algae could, via bioengineering, enable scientists to reroute metabolism toward beneficial bioproducts for energy, food, and human health. To that end, Berkeley Lab Biosciences researchers used C. zofingiensis as a simple algal model system to investigate conserved eukaryotic sugar responses, as well as mechanisms of thylakoid breakdown and biogenesis in chloroplasts.

Photosynthesis, Like a Moss

Using cryo-electron microscopy (cryo-EM), which allows an unprecedented level of resolution, Biosciences researchers compared the structure of photosystem I in the moss Physcomitrella patens with its structure in the small flowering land plant Arabidopsis thaliana, and in the green alga Chlamydomonas reinhardtii. Because moss evolved after algae but before vascular land plants, such comparisons can shed light on how plants evolved to move from the ocean to land.

Scientists Engineer Plants to Thrive on 25% Less Water

Krishna Niyogi, a faculty scientist in Molecular Biophysics and Integrated Bioimaging (MBIB) and chair of the Department of Plant and Microbial Biology at UC Berkeley, identified a protein called Photosystem II Subunit S (PsbS) involved in regulating photosynthetic light harvesting and hypothesized that increasing the amount of this protein in a plant might make photosynthesis more efficient. In collaboration with researchers at University of Illinois, Urbana, he put this theory to the test. In field trials, the researchers found that increasing the expression of the gene for PsbS, which is found in all plants, improved crops’ water-use efficiency—the ratio of carbon dioxide entering the plant to water escaping—by 25 percent, without significantly sacrificing photosynthesis or yields. The extra PsbS protein tricks plants into partially closing their stomata, the microscopic pores in the leaf that allow water to escape. The study, published March 6 in Nature Communications, is part of an international research project, Realizing Increased Photosynthetic Efficiency (RIPE), supported in part by the Bill & Melinda Gates Foundation. Read more at UC Berkeley News.

Biosciences Researchers ID Plant ‘Sunscreen’ Protein

A protein that protects plants from damage caused by too much light energy has been found by a team of researchers led by Kris Niyogi, faculty scientist in the Molecular Biophysics and Integrated Bioimaging Division. Alizée Malnoë, a postdoctoral researcher in Niyogi’s group, is the lead author on the study published in the journal The Plant Cell. Plants with deficient levels of the lipocalin protein are less able to dissipate excess light energy. Scientists will explore how this energy dissipation process is turned on and off, and whether manipulation of light usage could lead to higher crop yields. Read more in the Berkeley Lab News Center.

UCB/UIUC Project to Improve Photosynthesis Receives Ongoing Support

A University of Illinois Urbana-Champaign research initiative on which Biosciences’ Krishna Niyogi has been a longtime collaborator received a $45 million, five-year reinvestment to continue efforts to re-engineer photosynthesis in staple crops order to sustainably increase yields worldwide. The new round of funding for Realizing Increased Photosynthetic Efficiency (RIPE) comes from the Bill & Melinda Gates Foundation, the Foundation for Food and Agriculture Research, and the U.K. Department for International Development. Niyogi, a faculty scientist in Molecular Biophysics and Integrative Bioimaging (MBIB) and chair of the Department of Plant and Microbial Biology at UC Berkeley, has been involved with RIPE since its inception. His research related to the project focuses on relaxing the protective mechanisms plants have developed to avoid damage to leaves from high-intensity light. Read more from UC Berkeley College of Natural Resources.

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