Re-engineering Plants to Feed the World and Fight Climate Change

March 20, 2020 – We are on the cusp of a new green revolution. In the past, selective breeding of plants was the way we created better yields of food staples. But today we have new technologies that we can exploit to grow hardier plants even on land that would have been considered marginal for agricultural production in the recent past. So what are the 21st-century tools available to us?

CRISPR-Altered Staple Crops

Our ability to slice out bad genes and replace them with healthy ones has been revolutionary not only in medicine but also in agriculture. CRISPR is the technology of choice coming in a variety of flavours. The most notable is Cas9. Although there are other variations including CRISPR-SDN-1, 2, and 3, and CRISPR-Cpf1.

CRISPR is already altering wheat, corn, rice, and tomato crops. In wheat it is giving the plant the ability to resist powdery mildew fungus. In corn, rice, and tomatoes, it is increasing yields even in adverse environmental conditions such as drought.

What CRISPR provides is a low cost, easy-to-use tool for sustainable agriculture in the future. It can be used with every plant we grow allowing us to improve traits in food crops, the plants used for fallowing in between, and giving plants better environmental and disease tolerance.

Photosynthesis Re-engineered

Billions of years ago plants perfected turning sunlight into a powerful energy source to allow them to flourish. But photosynthesis is by no means perfect producing unproductive byproducts that are energy inefficient.

The Realizing Increased Photosynthetic Efficiency (RIPE) project out of the University of Illinois-Urbana-Champaign is out to eliminate these energy inefficient byproducts of photosynthesis. Among those funding the project are Bill and Melinda Gates. What the research hopes to accomplish is double the productivity of rice, corn, cowpea, soybeans, and cassava. They have modeled the 170-step chemical process plants use to harness sunlight. Studying various spectra and lighting conditions (when clouds cover the Sun for example), the research is showing how plants absorb and convert light into energy.

In other research, the University is looking at improving the functioning of the enzyme, Rubisco, responsible for capturing carbon dioxide (CO2) and converting it into sugar for the plant’s use. Rubisco has an inefficient trait because 20% of the time it makes mistakes grabbing an oxygen rather than CO2 molecule. This generates a needless process called photorespiration that robs the plant of some of the energy gained from sunlight. Re-engineering the photorespiration pathway to shorten it by as much as 40% is the current project that is increasing photosynthesis efficiency. Testing is being done using tobacco plants. Future research will transfer the new re-engineered pathways to the major food crops mentioned above.

Strengthened Plant Structures

Research being done at Cornell University is studying stem cells that generate the above-ground parts of plants from shoots to leaves, to stems and flowers. One type of stem cell called the shoot apical meristem (SAM) is deemed responsible for all of these structures. The work at Cornell is focused on SAM in corn with a goal to alter the plant’s architecture to improve both individual as well as group productivity.

At Bayer Crop Science, the former Monsanto, researchers are creating hybrid corn that is shorter and stronger to resist extreme weather events and allow farmers to plant it in greater density. These short-statured hybrids have more upright leaves and smaller tassels that allow them to harvest more sunlight, and to prevent green snap which can level of an entire field when winds or hail disrupt crops in the field.

Expanded Root Structures

In this category we are not talking about creating bigger root crops like potatoes, carrots, or casava, but rather enhancing root formation and giving plants greater resistance to decomposition to enable them to sequester carbon.

Joanne Chory, a plant biologist at The Salk Institute in San Diego, is harnessing plants to create a biological carbon sink. Plants are already good at absorbing CO2 but to help fight climate change the goal is to make them absorb even more by making staple crop root systems deeper. A substance called suberin which can be found in the rind of canteloupe both resists decomposition and captures CO2. So her team of biologists are creating plants with suberin-rich roots that when harvested keep the CO2 in the soil.

In a recent interview with Wired, she stated, “Every year plants and other photosynthetic organisms take up an incredible amount of CO2—like twentyfold more than we ever put up when we burn fossil fuels—but then at the end of the growing season most plants just die, and they decompose, and it goes back up as CO2. That’s been a real problem.” But by expanding root structures so they go deeper, when the plants die in the fall, the root structures remain with the carbon entrapped.

The research has identified three genetic controls, one that increases suberin, a second that enlarges root systems, and a third that makes them grow deeper. They are experimenting with a model plant called arabidopsis and hope within the next five years to duplicate these genetic traits, using traditional standard plant-breeding techniques, in corn, soybean, and rice.

Extreme Weather and Soil Tolerance

Global warming has altered normal weather patterns. Areas that had an occasional drought like California, Southern Africa, and Australia, are experiencing longer periods of bone-dry conditions both in the air and soil. Altering the genetics of plants to grow even when water is scarce, and the heat is extreme has involved the use of CRISPR technology.

DuPont is using CRISPR to edit a single gene responsible for expressing an enzyme, ARGOS8. Getting the gene to over-express the enzyme contributes to its hardiness and gives the plant the ability to grow even in drought conditions. Testing in eight different locales across the United States, the gene-altered corn has shown its superiority over traditional plants created through selective breeding to try and develop similar resistance. The corn still awaits regulatory approval for commercial planting.

Meanwhile, a group of Indian scientists has created salt-tolerant transgenic rice by altering one of the plant’s genes. An isolated gene, PcIN01, produces an enzyme that synthesizes inositol creating a higher salt tolerance. Why is this important? Because in coastal farms where sea level rise is a threat, and increasingly aquifers are seeing intrusions of saltwater, the ability to continue to grow rice and achieve high yields is imperative. For countries like the Philippines, Bangladesh, India and others in South Asia, growing rice in high-salt soils may make a difference between bumper harvests, or famine.