Hacking Photosynthesis

13 January, 2019

We will all be dead without the Sun. That we all know. But even if the sun shone 24 hours a day, we will all be dead without plants. Really. Plants keep the world going. We eat a lot of plants – and the animals from which we obtain meat for consumption also consume plants. Furthermore, plants inhale Carbon Dioxide and produce healthier air. The process through which plants get the energy for sustenance (and all other stuff) is called Photosynthesis which means something like ‘producing with light’.

This is fundamental to the life cycle on Earth. But how does photosynthesis work? There’s a big molecule, a protein, inside the leaves of most plants. It is called Rubisco. It is probably the most abundant protein in the world. Rubisco has one job.

It picks up carbon dioxide from the air, and it uses the carbon to make sugar molecules. It gets the energy to do this from the Sun. This is photosynthesis, the process by which plants use sunlight to make food, the foundation of life on Earth.

But Rubisco is not perfect. It has one almost fatal flaw. Unfortunately, Rubisco does not know how to grab only Carbon Dioxide from the air. It also picks up oxygen. But this poses a huge problem for the plant as this leads to the formation of a toxic compound in the plant. It has to do extra work and spend extra energy for detoxification, a process called Photorespiration. This has in fact been called ‘one of the biggest mistakes’ of evolution.

Ripe

Plants have a complicated ‘chemical assembly line’ in their cells to carry out this detoxification, but the process uses up a lot of energy. This means the plant has less energy for actually making food. However, some crops including corn and sugar cane have developed a workaround for Rubisco, making them much more productive. Photorespiration is anti-photosynthesis in the sense that it costs the plant precious energy and resources that it could have invested in photosynthesis to produce more growth and yield.

Many scientists around the world have been trying to ‘hack’ photosynthesis for years, but a team from the University of Illinois has emerged first. There, a research program called Realizing Increased Photosynthetic Efficiency (RIPE), has run for the last five years trying to fix Rubisco’s problem.

They first experimented with tobacco plants, because tobacco is easy to work with. The researchers inserted some new genes into these plants, which shut down the existing detoxification assembly line and set up a new one that is much more efficient.

Photorespiration normally takes a complicated route through three compartments in the plant cell. Scientists engineered alternate pathways to reroute the process, drastically shortening the trip and saving enough resources to boost plant growth.

This resulted in super tobacco plants that grow faster and up to 40 percent bigger than normal tobacco plants. And yes, this was not confined to the laboratory.

These measurements were done both in greenhouses and open-air farm plots. Their research has been published in the prestigious Science magazine.

These scientists now are trying to repeat the process with plants that people rely on for food, such as, tomatoes and soybeans.

They will also be working with cowpea, or black-eyed pea, which is a staple food crop for a lot of farmers in sub-Saharan Africa. One can indeed imagine the effects of more efficient photosynthesis in the poorest regions of the world. The funders of this project include the U.S. Department of Agriculture and the Bill and Melinda Gates Foundation.

It will be many years, though, before any farmer anywhere in the world plant crops with this new version of photosynthesis. Researchers will have to find out whether it means that a food crop actually produces a bigger harvest, while convincing Government regulators and consumers that the crops are safe to grow and eat.

There is an irrational fear regarding Genetically Modified Organism (GMO) food, even though there is no conclusive evidence that they cause disease or deformities. The public however should be assured that the plants with the photosynthesis hack pose no danger to people and animals.

Precision Agriculture

In any case, photosynthesis is just one component of a plant’s needs. Plant growth, in man-made fields or in the wild, depends on the availability of water, nitrogen and phosphorus, not on photosynthetic capacity alone. Farmers generally add water and NPK fertiliser to their crops, though wild plants have to find these on their own. And lest someone think that the sun is essential for photosynthesis for all plants, plenty of plants grow well under artificial light. In fact, indoor agriculture has been proposed as one solution to the impending food crisis in some parts of the world. Moreover, soil-less and artificial light plant growth will be essential for future manned space missions being planned for Mars.

Agriculture is ripe for modernisation in many developing parts of the world where crop yields are still low compared to those of the developed world. Boosting crop yields is essential with the world predicted to have 10 billion people by 2050.

That is three billion extra mouths to feed and a possible 70 percent extra demand for food, but arable land is not getting any bigger. The solution is to improve crop yields and also adopt innovative methods of agriculture such as vertical farming, soil-less farming and indoor farming.

And there is a whole new revolution coming to traditional agriculture too – including self-driving tractors and harvesters, crop-spraying drones, robots, Artificial Intelligence and satellite sensing. There is even a name for agriculture that combines the best elements of technology - precision agriculture.

Internet of Things

The goal is to use automated driving technology, computer vision, telematics, and cloud-based mobile applications to help farmers double or triple their yields—a feat that will be key to keeping up with global food demands as the Earth’s population grows over the next 30 years.

The Internet of Things (IOT) will also help agriculture. Some machines are stuffed with sensors and software that gather data, process it with machine learning, and beam it into mobile apps. The sensors are the eyes of the machine. The software and mobile apps bring the data to life.

The other major challenge is Climate Change, which has the potential to cause a severe disruption to our crop cycles. A Recent analysis that looked into the climate impact on crop yields produced sobering results.

The study’s authors said that for each 1° Celsius rise in global mean temperature there would be a 7.4% decrease in yields of corn, a 6% decrease in yields of wheat, and a 3% yield decrease in rice. It is thus vital to keep Climate Change in check as other advances could be nullified if it reaches unmanageable levels.