b'16 Carnegie Science|Summer 2019Plant Genesthat ShapedOur World Chlamydomonas is a group of single-celled, photosynthetic algae found around the globe in fresh and saltwater, moist soil, and even snow. They are used widely by plant biologists to study fundamental processes. The cells in this image are stained with a fluorescent dye. Image courtesy Arthur GrossmansunlightThe creation of a new library of mutants of the single-celledoxygenphotosynthetic green alga Chlamydomonas reinhardtii enabled a Carnegie and PrincetoncarbonUniversity-led team of plantdioxidescientists to identify more than 300carbohydratesgenes that are potentially required for photosynthesis. Photosynthesis is the process by which plants, algae, and some bacteria convert energy from sunlight into Arthur Grossman has been a staffcarbohydrates and fill our planetswaterscientist at Carnegies Department of Plant Biology since 1982. atmosphere with oxygen. Nature Image courtesy Carnegie Institution Genetics Photosynthesis is the process by which plants, algae, and some bacteria convertpublished their findings.for Science Chlamydomonas represents aenergy from sunlight, with carbon dioxide and water into carbohydrates for food. Oxygen is emitted into the atmosphere as a byproduct. group of algae found around the globe in fresh and saltwater, moistImage courtesy Wikimedia Commons (CC BY-SA 4.0) soil, and even snow. They are photosynthetic and readily grow in the lab, even in darkness with the right nutrients. This makesThis work opens the door to a new understanding of the Chlamydomonas an excellent research tool for plant biologists,various processes associated with photosynthetic function, which particularly in the genetics of the photosynthetic apparatus andare of fundamental importance to our planets food supply, as well other biochemistry, such as responses to light and stress.as, of course, to replenishing the atmospheric oxygen that we In this study, the research team created a library of aboutbreathe, said Carnegie coauthor Arthur Grossman. 80,000 Chlamydomonas mutants, which they used to identify 303The research teams findings indicate that nearly half of the genes thought to participate in photosynthesis. Of these, 65genes that are necessary for plants to create carbohydrates by genes encode proteins that were already known to play aphotosynthesis have not yet been characterized. photosynthetic role. The remaining 238 genes had no previouslyThis is remarkable, considering that genetic research on this known role in photosynthesis, making them targets for furtherfundamental process began in the 1950s, said Princeton coauthor research. Twenty-one of them are considered high priorities forMartin Jonikas, who was formerly at Carnegie. Our library additional investigations.demonstrates how much work remains to be done in revealing mechanisms underlying the biochemical process that shaped our planets history and created the conditions that allowed life to SUPPORT:The National Science Foundation, the National Institutes of Health, a Germanthrive here.Academic Exchange Service research fellowship, Simons Foundation fellowships,Zhiyong Wang, acting director of Carnegies Department of Plant and a Swiss National Science Foundation Advanced Postdoc. Mobility fellowshipBiology, added: This work really illustrates the power of using high-supported this project. throughput genetic techniques to address major issues in biology. '