So putting aside the technology that is GMO, what other means do agricultural scientists have to improve upon the food we eat?
Meet Ranger Russet potatoes. They are not GMO. They are genetically altered using a new technique that involves disabling a single gene. The end result a potato that stores better in the cold, lasts longer and when fried doesn’t produce acrylamide. The latter is a suspect carcinogen.
The gene was removed using TALENs (transcription activator-like effector nucleases), a technology pioneered by Editas Medicine of Cambridge, Massachusetts. The U.S. Department of Agriculture in August gave the Ranger Russet its blessing stating it would not have to go through the elaborate field testing that happens with GMO.
Ranger Russet, besides being a better potato for the reasons described above, was developed in a year. The creators of the potato state that if they had used selective breeding technology, the way plants have been improved by humans since the dawn of the Agricultural Revolution, the timeline would have been as long as ten years.
But it doesn’t end with the Ranger Russet. Gene editing could be the world’s answer to feeding the billions of mouths that will be added to our human population between now and the end of the century. Forecasts by mid-century indicate 9.5 billion. From there it gets murky…will the population continue to spiral upward or will we see it plateau and begin to fall. In any event feeding the 9.5 billion expected in the 2050s will be a colossal task based on our current agricultural practices.
The same technology is being used today to experiment with ways to supercharge photosynthesis in plants so that they grow faster. Boosting photosynthesis involves more than one gene. Fortunately researchers can look to evolution and the natural history of our planet to find potential answers. At some point around 10 million years ago, carbon dioxide levels in the atmosphere declined and this selected out plants that were more efficient users of the gas. These plants are categorized as C4 photosynthesizers. Botanists first discovered this in the mid-1960s. They noticed a difference in the way photosynthesis happened in plants like corn and sugar cane versus rice, wheat and other cereal crops. They categorized one as C4 and the other as C3.
What was the difference? C4 plants assimilate CO2 creating a molecule containing 4 carbon atoms. C3 plants create a 3-carbon molecule. C4 plants use a two-pathway approach which boosts CO2 levels while shielding the plant from the destructive effects of the oxygen byproduct. Specific genes within a C4 plant produce critical enzymes in the process. These enzymes aren’t switched on in C3 plants. Finding the genetic switch common to both types of plants and turning it on within C3s will be modern botany’s greatest contribution to food security.
In December 2014, twelve laboratories, part of the C4 Rice Consortium, announced the development of a supercharged rice exhibiting C4 characteristics. The engineering changes within the rice genome impact a family of genes involved in the development of chloroplasts, the organelles in plants where photosynthesis occurs. The altered rice plants exhibit both C4 and C3 characteristics. Scientists are still not sure how many genes need to be manipulated to create a C4 rice but they are getting closer and most believe the C4 photosynthetic revolution is coming to staple food crops within the next two decades. That will be just in time to address world population growth, and may also alleviate the impact climate change will have on conventional crop yields.
]]>
To understand the implications you need to know a little more about plant anatomy and physiology. Plants use photosynthesis to harvest the energy from sunlight and CO2 and convert these two into sugar. Plants over time have evolved two different methods of photosynthesis. One is called C3, the predominant method. The other, C4, is an adaptation that gives those plants with it a more efficient production mechanism with the added benefit of being able to better deal with more intense sunlight, high levels of heat, low nitrogen soils and prolonged drought. The C3 photosynthesis mechanism evolved early in Earth’s history when there was much more atmospheric CO2 and less free oxygen. The C4 adaptation came later after C3 plants added considerable amounts of free oxygen to the atmosphere.
C4 plants feature an extra layer of bundle sheath cells encircling the core cells involved in converting sunlight and CO2 into sucrose. And C4 plants, unlike C3 produce no byproduct associated with handling oxygen that needs to be further degraded, making the latter 50% less efficient in making sucrose. And although researchers have understood the difference in the two mechanisms what they didn’t know was the underlying genetics responsible for C4. The discovery of Scarecrow means that scientists through genetic modification can begin to introduce C4 into C3 plants.
Why is this important? Because wheat and rice, two principle food staples are both C3. With 7 billion human mouths to feed today, and projections of population growth to 9.5 billion by mid-century, and with the increasing impact of global warming on weather patterns, the promise of 50% higher crop yields is significant. C4 versions of C3 plants will grow in a hotter, drier world and will need less nitrogen-based fertilizers.
For those who oppose genetic modifications to food crops, this discovery may further spook them. But I am increasingly convinced by the hard science that GMO represents a key strategy for our species as we progress through the 21st century. Without it we will find the limits imposed by changing climate and finite agricultural land a potential death sentence for billions.
]]>