Realizing Increased Photosynthetic Efficiency

|style="width: 80%;" |With the rapid increase in high-performance computing, it has become possible to simulate photosynthesis in dynamic models in which each of the coupled reactions is fully represented, providing a realistic in silico representation of the entire process with a system of linked differential equations. We have developed realistic renderings of the crop leaf canopies to more accurately predict the dynamics of crop microclimate and light energy distribution. We can now combine these two kinds of simulations into one robust modeling system.

|style="width: 80%;" |Through photoprotection, plants protect themselves against damage from high light exposure by dissipating excess light energy as heat. However, this protective process continues when the leaf is shaded by a cloud or by another leaf, which limits photosynthesis.{{cite web|url=https://www.youtube.com/watch?v=Av0dTk9KzlY |title=Turning up plant efficiency |publisher=youtube.com |date= 21 November 2016|accessdate=2017-02-02}} RIPE has identified and up-regulated the genes that speed up this relaxation, which has increased yield by 14%-20% in replicated field trials.{{cite journal|title=Improving photosynthesis and crop productivity by accelerating recovery from photoprotection |publisher=sciencemag.org |date=2016-11-18 |doi=10.1126/science.aai8878 |last1=Kromdijk |first1=Johannes |last2=Głowacka |first2=Katarzyna |last3=Leonelli |first3=Lauriebeth |last4=Gabilly |first4=Stéphane T. |last5=Iwai |first5=Masakazu |last6=Niyogi |first6=Krishna K. |last7=Long |first7=Stephen P. |journal=Science |volume=354 |issue=6314 |pages=857–861 |pmid=27856901 |bibcode=2016Sci...354..857K |osti=1832459 |s2cid=26991449 |doi-access=free }}

|style="width: 80%;" |RuBisCO regularly makes the mistake of reacting with oxygen instead of carbon dioxide. The resulting chemicals must be recycled back into the production line, wasting energy through a process called photorespiration. Some bacteria recycle these chemicals more efficiently. RIPE is engineering these more efficient pathways—or shortcuts—into crops.{{cite journal|first=Rachel |last=Ehrenberg |journal=Knowable Magazine|url= https://www.knowablemagazine.org/article/sustainability/2017/photosynthesis-fix |title=The photosynthesis fix |publisher=Annual Reviews |date=2017-12-15 |doi=10.1146/knowable-121917-115502 |accessdate=2018-04-03|doi-access=free }} In a landmark study, RIPE scientists engineered photorespiratory shortcuts that increased yield by 40 percent.{{cite journal|title=Synthetic glycolate metabolism pathways stimulate crop growth and productivity in the field |publisher=sciencemag.org |date=2019-01-03 |doi=10.1126/science.aat9077 |last1=South |first1=Paul F. |last2=Cavanagh |first2=Amanda P. |last3=Liu |first3=Helen W. |last4=Ort |first4=Donald R. |journal=Science |volume=363 |issue=6422 |pages=eaat9077 |pmid=30606819 |pmc=7745124 }}

|style="width: 80%;" |The Calvin Cycle, a key part of photosynthesis, is a multi-step process that regenerates the carbon dioxide acceptor molecule used by RuBisCO to create sugar that fuels plant growth. Each step relies on protein catalysts known as enzymes. RIPE is optimizing the amount of each enzyme so that the entire photosynthetic process becomes more efficient.{{cite web|url=https://phys.org/news/2017-06-incremental-discovery-day-photosynthetic-breakthrough.html |title=Incremental discovery may one day lead to photosynthetic breakthrough |publisher=phys.org |date=2017-06-29 |accessdate=2018-04-03}}

|style="width: 80%;" |RIPE has surveyed a wide range of plants and algae to find forms of RuBisCO that are faster and less likely to mistake oxygen for carbon dioxide. The project is now engineering crops with these better-performing forms of RuBisCO or modifying existing RuBisCO to match these more efficient forms.{{cite web|url= http://www.feedstuffs.com/story-plant-enzyme-may-key-future-food-security-45-144493|title=Plant enzyme may be key to future food security

|publisher=feedstuffs.com |date=2016-07-27 |accessdate=2017-06-15}}{{cite web|url=http://www.fareasternagriculture.com/crops/agriculture/enzyme-biodiversity-key-to-future-of-crops |title=Enzyme biodiversity key to future of crops |publisher=fareasternagriculture.com |date=2016-08-10 |accessdate=2018-04-03}}{{cite web|url=https://www.sciencedaily.com/releases/2016/01/160128155105.htm |title=Enzymes with potential to increase wheat yields |publisher=sciencedaily.com/ |date=2016-01-28 |accessdate=2018-04-03}}

|style="width: 80%;" |Layers of crop leaves create a canopy, but the top leaves receive more light than they can use while the bottom leaves are starved for light. By changing the color and angle of the leaves, light is more evenly distributed throughout the canopy to increase photosynthetic activity throughout the plant.{{cite web|url=http://www.farmfutures.com/story-lighter-colored-upper-leaves-may-crop-photosynthesis-hack-8-126107 |title=Lighter colored upper leaves may be crop 'photosynthesis hack' |publisher=farmfutures.com |date=2015-04-06 |accessdate=2018-04-03}}

|style="width: 80%;"|RuBisCO catalyzes the extraction of carbon dioxide from the air into sugar to fuel the plant's growth, but is limited by the supply of carbon dioxide. Using mechanisms from algae, plants are being engineered to pump carbon dioxide to RuBisCO to boost photosynthesis.

|style="width: 80%;" |Mesophyll conductance measures how easily carbon dioxide can diffuse through the leaf to reach RuBisCO. RIPE is modifying pathways to help carbon dioxide move through the cell membrane, cytoplasm, chloroplast envelope, and chloroplast stoma to reach RuBisCO.

|style="width: 80%;" | Transformations are confirmed, from gene expression to production of the targeted proteins, and then phenotyped in the greenhouse and tested in replicated field trials. Once a trait is proven to be successful, we begin the more difficult and time-consuming task of transforming staple food crops, including soybeans, cassava, cowpea, and rice.