New, scalable approaches to capture significant amounts of atmospheric carbon to reduce CO2 are urgently needed to slow, and perhaps even reverse, global warming. Living organisms, like plants, are nature’s scalable solution, having the potential to both capture atmospheric carbon through photosynthetic CO2 fixation and store it through carbon sequestration in its roots. But several studies indicate that photosynthesis is under-achieving and engineered improvements have been demonstrated. The goal of this project, in collaboration with Professors David Savage in MCB and Krishna Niyogi in PMB, is to accelerate the process of identifying genetic fixes that improve CO2 fixation.
Achieving this goal will be realized through a novel screening approach that will lead to identification and prioritization of promising gene edits. The ultimate target of these efforts is Sorghum bicolor, which is the fifth most widely grown cereal crop worldwide. It is primarily used in animal feed and biofuels in the US. Some advantages of sorghum for biofuel uses is that it uses the more efficient C4 photosynthetic pathway and it is drought and flood tolerant, traits important during changes in. However, sorghum has a relatively long lifecycle; seed to seed is ~4.5 months, making it difficult to make rapid progress in determining function of genes that can be used to improve photosynthetic efficiency and biomass production. Thus, for initial screening of genes we will use Setaria viridis, a C4 grass with a shorter lifecycle of about 7-8 weeks.
The approach to identifying genes of interest will initially utilize plant-derived protoplasts from Setaria viridis to screen genome edits in a high-throughput assay. From the candidate edits, the most promising ones will be further evaluated by creating editing constructs to stably transform into Setaria. Evaluation of edited Setaria will include various physiological and biochemical assays to determine effects of edits on photosynthesis and other traits relevant to carbon sequestration. Final candidate edits from the Setaria evaluation will be stably transformed and edited in Sorghum bicolor. These edited plants will be screened to assess effects on photosynthesis, biomass and other characteristics of potential importance to carbon sequestration.
Essential to these efforts are effective methods to transform Setaria and sorghum and achieve biallelic gene edits. Historically grasses and cereal crops, like Setaria and sorghum, have been difficult to transform. Our laboratory has focused on achieving transformation and editing success in both plant species, but much remains to be optimized. At present two approaches are being used for Setaria – callus-based and dry seed-based transformation. Once efficiencies are established, one method will be chosen to evaluate edits, identified from the protoplast screen, in stably transformed Setaria. For the next step in sorghum, transformation efficiencies over 30% have been achieved, using the developmental genes, babyboom (BBM) and wushel (WUS). Chimeric editing efficiencies in sorghum of over 20% have been achieved; current efforts focus on increasing efficiency of biallelic edits. The goal of this SPUR project is on continued development and use of these engineering and editing methods in Setaria and sorghum with genes identified in the protoplast screening project in collaboration with the Savage and Niyogi laboratories.
The duties and goals of the student will depend on their skill level. The student might care for plants, plant seeds, harvest seeds, perform in vitro tissue culture and transformation for engineering and editing, and conduct biochemical and molecular studies on the transformed materials. The student may also be involved in preparing materials for the various analyses that will be performed. The student will also be involved in documentation of the transgenic plants and tending plants in growth chambers and the greenhouse, collecting experimental materials and data when necessary. The student will work directly with Research Assistants, other undergraduates and the Principal Investigator. Students will participate in lab meetings and be expected to contribute to presentations and publications, as needed. The time commitment required will be negotiated with the student.
Enthusiasm for research is necessary; previous laboratory experience outside the classroom is desirable. Care-to-detail and commitment to scheduled work times are critical.