Algae play a major role in two areas of global concern, climate change and renewable biofuels, are emerging as prime topics on the world stage. Algae of all types account for approximately one-half of carbon dioxide (CO2) recycled from the atmosphere and 'fixed' via photosynthesis into sugars, proteins, and organic substances needed by all living organisms on earth, including humans. Thus, algae are critical to maintaining low levels of atmospheric CO2, a potent greenhouse gas. The fact that many fast growing, easy to culture algae also are oil-rich has recently drawn the attention of scientists and engineers around the globe to the possibility of using algae as an abundant, potentially inexpensive, source of renewable and sustainable biofuels that will lessen the needs for highly polluting, expensive and environmentally nonfriendly fossil fuels. Research to be conducted collaboratively between the laboratories of Dr. Don Weeks at the University of Nebraska-Lincoln and Dr. Martin Spalding at Iowa State University is aimed at elucidating the mechanisms underlying the ability of algae to serve as ?super sponges? of CO2 from the environment. The Spalding/Weeks laboratories recently discovered two proteins, HLA3 and LCIA, which provide the algal cell, Chlamydomonas reinhardtii, with the ability to scavenge very low levels of inorganic carbon (CO2 and bicarbonate) from their aquatic environment. Ongoing research sponsored by NSF will focus on the molecular mechanisms by which these inorganic carbon transporters work, where in the cell they are located and how these molecules interact with other components of the cell to allow efficient CO2 uptake and utilization for photosynthesis. In addition, the use of the newly discovered inorganic carbon transporters to augment CO2 uptake and photosynthetic efficiency in algal cells involved in biofuel production will be explored.
Broader Impacts: This research will contribute significantly to the training of undergraduate and graduate students and postdoctoral associates participating in the project at both Iowa State University and at the University of Nebraska. It also will contribute to broadening the education of high school and undergraduate students and of high school biology teachers that will participate during summer internships and camps. Because members of underrepresented groups (e.g., African Americans, Hispanics, and Native Americans) are specifically recruited for the high school and undergraduate internships, this research also will provide opportunities for broadening educational experiences for these groups. Postdoctoral associates and students trained in our projects will find ample opportunities in academic and industrial positions focused on algal biology and biotechnology and its application to critical societal needs.
The initial goal of our NSF-funded research was to expand knowledge and understanding of how algae cells are able to maximize photosynthesis by efficiently taking up carbon dioxide. This is a process that is essential for algae and plants that make (directly or indirectly) all of the food on earth and, thus, a process that is essential for all life on earth. Our project succeeded in greatly expanding our knowledge of the components and mechanisms associated with the "carbon concentrating mechanism" in the alga, Chlamydomonas reinhartii, the most studied and understood alga in the world. This new information has the potential to allow scientists to modify algae to be more productive. This is important, for example, if oil-rich algae are to be utilized in the not to distant future for the production of renewable biofuels - the goal of many scientists in universities and in industries around the globe. As often happens in science, there was an unexpected but highly important development that occurred during our research - a development that already has had a highly benefitial outcome for the nearly one-half of the world population that depend on rice as their prime food supply. That new finding was that we could use a very recently developed scientific technique called TALE Effector Nuclease (TALEN) to inactivate a specific gene in rice plants. That gene is one that causes rice plants to be susceptible to a major rice disease called bacterial blight. Infection of rice with the bacterium that causes the blight disease results in the infected plant losing vigor and yielding much less grain than normal. Thus, our success in knocking out the gene that causes rice to be prone to bacterial blight means that people in many parts of Asia and the rest of the world where rice is often in short supply may benefit from having a larger and more dependable supply of rice for their daily nourishment. How did this unexpected development occur? It resulted from our desire to "knockout" some of the genes that are involved with the algal carbon concentrating mechanism so that we could determine exactly what they do and if they play a major role or a minor role in helping the agal cell take up CO2 efficiently. As soon as we learned scientists at Iowa State Unversity and in Germany had discovered that molecules call TALE Effectors could efficiently recognize one specific DNA sequence out of millions of such sequences in plant cells and that the recognition system was "modular", we contacted two of the scientists involved in the TALE breakthrough and set up a collaboration to design and build TALE Effectors that could target algal genes of interest to us for "knockout". Based on earlier work with molecules called zinc finger nucleases that can (with less efficency) target DNA sequnces and cause a break in the two DNA strands, we were able to design TALEs with an attached nuclease that, indeed, could target our genes and cause them to be disruppted in such a way that the genes carrying the broken DNA strands would be mutated and no longer functional. More recently, we have achieved similar results with an even more promising gene-knockout technology called CRISPR/Cas9. Although our original target genes were in algae, we realized that the TALEN and CRISPR/Cas9 technologies would be highly useful in targeting genes in agriculturally-important crops - such as rice. In a collaboration with Dr. Bing Yang at Iowa State University, a set of TALENs were designed and tested that ultimately gave rise to TALENS that successfully targeted knockout of the gene causing susceptibility to bacterial blight. Without the financial support of NSF and the freedom to turn our attention to scientific objectives that we can envision as having the potential to cause "game-changing" advances in either fundamental academic science or in application of science to practical purposes, we could not have made the important contributions to society described above. As scientists, we learn to "expect the unexpected" and to take new discoveries in profitsable directions that were not envisioned as we set out on our original quest for new knowledge.
