A molecular biologist at the Salk Institute shows me a greenhouse full of plants that use a photosynthesis called C4. Plants with that kind of operating system are better suited to thrive in dry and hot temperatures.
“And because climate change is going to expand the number of environments where it’s dry and high in temperature, that’s why this research is so important,” said Joseph Swift, a postdoctoral researcher.
Swift was co-author of a paper that examined how those hardy C4 plants evolved millions of years ago. All plants photosynthesize to survive, making oxygen and food in the process. But they don’t all do it in the same way.
The paper, published in the journal Nature, offered a promise that gene editing — available today — could give many more plants that kind of resilient, efficient photosynthesis found in C4 plants.
Today, the vast majority of plants still use that ancient form of photosynthesis, called C3, referring to three carbon molecules. Those plants include some very well-known crops.
“Plants like rice, soybeans. And other crop species,” said Joe Ecker, professor of genetics at Salk Institute. “Wheat is also a C3 plant and it would be another interesting target to convert to C4.”
The increased efficiency and drought tolerance of C4 is due to its ability to correct some problems with C3, from which it evolved.
In those C3 plants carbon dioxide is too often mixed with oxygen during photosynthesis, and that wastes energy. Also pores on their leaf surfaces are open too much, causing the plant to lose water.
Ecker, the senior author of the paper, published in Nature, said converting a plant like rice from C3 to C4 is the ultimate goal. Like wheat, rice is another target for conversion. It is the number two crop in the world. Corn, a C4 plant, is number one.
“So if we would be able to engineer a rice plant to be a C4 plant we could increase its efficiency for photosynthesis and yield by 50%,” Ecker said.
In nature, evolutionary forces have changed plants from C3 systems to C4 about 60 times. Doing it in the lab, with gene editing, will be difficult and it could require 20 years.
Also, the expectation of higher crop yields is just that, an expectation. It’s not a certainty.
Carolyne Corelis
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KPBS
But Ecker said another expectation, nearly 10 billion people on earth by 2050, means we need to figure out a way to help plants produce more food.
“So that’s really the goal here is to take a plant that has a worldwide importance and increase the grain yield so we have a population that can be fed,” he said.
Scientists at the Salk Institute worked with scientists at Cambridge University in England to reveal the genetic underpinning of photosynthesis.
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