I have come across a fascinating research on engineering photosynthesis. We have all read photosynthesis in our middle school level - how plants use energy from sunlight to convert carbon dioxide and water into food. But we do not know photosynthesis have some flaws. It turns out that plants are quite inefficient when it comes to using the sun’s energy. Just a fraction of the sunlight shining on a plant ends up fueling its growth, which means our crops are producing far less food than they could be.
A group of researchers from RIPE (Realizing Increased Photosynthetic Efficiency)
is aiming to fix that by giving photosynthesis a tune up. If successful, their research is expected to double the productivity of some of our most important crops—like rice, maize, tobacco, soybeans, and cassava.
That would be a much-needed breakthrough because the world is facing a crisis and we’ll need to produce 60 to 70 percent more food by 2050. At the same time, climate change is putting additional stresses on our food supply because of erratic rainfall, severe droughts, and the spread of pests and crop diseases. No single solution will solve this global food crisis. We’ll need to develop innovations in all areas of agriculture to increase productivity. Improved seed varieties for crops that are resistant to drought, flood, pests, and disease. Better data to help farmers manage their crops and livestock more efficiently.
RIPE scientists began their research by modeling the entire 170-step chemical process of turning sunlight into energy. Using computer simulations, they explored which changes might lead to the biggest increases in productivity—in the same way an efficiency expert might make improvements to a car production line to maximize output.
One interesting area of research involves making plant absorb more sunlight efficiently. While light is essential for a plant’s survival, too much high-intensity light can cause damage to the plant. To protect themselves, plants have developed mechanisms to siphon off some of the sun’s energy as heat when they are in direct sunlight. But this creates a problem when the sun goes behind a cloud and the plant is in the shade. The plant’s protective mechanism doesn’t adjust quickly to the reduced light, inhibiting the process of photosynthesis for minutes or sometimes hours. RIPE researchers discovered a way to speed up this transition, allowing the plant to continue with photosynthesis even with light fluctuations.
Another critical area of research involves an enzyme known as Rubisco, which captures carbon dioxide and turns it into sugars for the plant. Some researchers are working to speed up Rubisco activity in the plant, which would result in higher crop productivity. Other researchers are trying to fix an inefficiency created by Rubisco: It has a hard time distinguishing carbon dioxide from oxygen. So, about 20 percent of the time Rubisco accidently grabs an oxygen molecule instead of a carbon dioxide molecule. This results in the creation of a compound that must be recycled by the plant through a process known as photorespiration. Photorespiration is long and complicated, costing a plant energy and resources that it could use for growth. To solve this, researchers have engineered an alternative pathway to drastically shorten the photorespiration process and save energy.
Apart from this the researchers found missing link in algal photosynthesis found, which offers opportunity to improve crop yields. Algae evolved specialized carbon dioxide concentrating mechanisms (CCM) to photosynthesize much more efficiently than plants. Whereas carbon dioxide diffuses across cell membranes relatively easily, bicarbonate (HCO3-) diffuses about 50,000 times more slowly due to its negative charge. The green algae transports bicarbonate across three cellular membranes into the compartment that houses Rubisco, called a pyrenoid, where the bicarbonate is converted back into carbon dioxide and fixed into sugar. Creating a functional CCM in crops will require three things: a compartment to store Rubisco, transporters to bring bicarbonate to the compartment, and carbonic anhydrase to turn bicarbonate into carbon dioxide.
A new computer model incorporates how microscopic pores on leaves may open in response to light--an advance that could help scientists create virtual plants to predict how higher temperatures and rising levels of carbon dioxide will affect food crops. The current research is focused on simulating the behavior of what are known as stomata--microscopic pores in leaves that, in response to light, open to allow water, carbon dioxide, and oxygen to enter and exit the plant. increasing one specific protein could prompt plants to close their stomata partially--to a point where photosynthesis was unaffected, but water loss decreased significantly. This study's experimental data was used to create the newly improved stomata model introduced today.
Computer modeling has been a major advance in crop breeding. The father of modern genetics, Gregor Mendel, made his breakthrough discovery that pea plants inherit traits from their parents by growing and breeding more than 10,000 pea plants over eight years. Today, plant scientists can virtually grow thousands of crops in a matter of seconds using these complex computer models that simulate plant growth.
Stomatal models are used together with models for photosynthesis to make wide-ranging predictions from future crop yields to crop management, such as how crops respond when there is a water deficit. In addition, these models can give scientists a preview of how crops like wheat, maize, or rice could be affected by rising carbon dioxide levels and higher temperatures.
The research is on in this line but there are still more undiscovered secrets behind the photosynthesis story. Much of the field testing of these improvements to photosynthesis has been done using tobacco plants. While tobacco plants are not food crops, they are a convenient proof-of-concept crop because they are easy to transform genetically and they produce a large amount of seed, shortening testing cycles. In the next phase of research, scientists are working to transfer these new genetic traits to food crops, including cowpea, cassava, and soybeans. I’m excited about the progress made by the RIPE team and I look forward to hearing more about their discoveries in the future.
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