Newly Discovered Enzyme Could Create Crops That Thrive in Dry, High CO2 Conditions

new plant enzymes image

Photo via UCSD, Credit: Julian Schroeder Lab

Researchers at University of California San Diego have discovered particular plant enzymes that can make a big difference in food safety as the planet copes with two major problems: higher and higher levels of carbon dioxide and lower and lower water resources. The enzyme causes the plants to react to CO2 and change how they use their pores, and by manipulating the enzyme, researchers believe new, more CO2- and drought-tolerant crops could be created.

Plants use tiny breathing pores that bring in CO2 and emit H2O. Until now, scientists knew that the pores can tighten to save water when there is enough CO2 in the atmosphere, but they didn't know how...until now. Protein sensors control the response, and scientists believe that by controling those protein sensors, new versions of plants can be created that take full advantage of elevated CO2 levels all while conserving water, which means more CO2 being absorbed from the atmosphere by crops that require less watering.

A team led by Julian Schroeder, professor of biology at the University of California, San Diego, made the discovery.

"A lot of plants have a very weak response to CO2. So even though atmospheric CO2 is much higher than it was before the industrial age and is continuing to increase, there are plants that are not capitalizing on that. They're not narrowing their pores, which would allow them to take in CO2, while losing less water," he said. "It could be that with these enzymes, you can improve how efficiently plants use water, while taking in CO2 for photosynthesis. Our data in the lab suggest that the CO2 response can be cranked up."

Here is how the enzymes work:

Schroeder's team identified a pair of proteins that are required for the CO2 response in Arabidopsis, a plant commonly used for genetic analysis. The proteins, enzymes called carbonic anhydrases, split CO2 into bicarbonate and protons. Plants with disabled genes for the enzymes fail to respond to increased CO2 concentrations in the air, losing out on the opportunity to conserve water... By adding normal carbonic anhydrase genes designed to work only in guard cells [the research team was] able to restore the CO2-triggered pore-tightening response in mutant plants.

Adding extra copies of the genes to the guard cells actually improved water efficiency, the researchers found. "The guard cells respond to CO2 more vigorously," said Honghong Hu, a post doctoral researcher in Schroeder's lab and co-first author of the report. "For every molecule of CO2 they take in, they lose 44 percent less water."

While many people disagree with some types of engineering for crops, this could be one modification that we have to make on some plant species simply to be able to eat in a world that has changing atmospheric conditions. As the UCSD article points out, modifying the crops to be more responsive to CO2 could help farmers in places like California where agriculture is a major industry and competition for water resources is fierce - and incredibly damaging to rivers and streams.

More on Crops and CO2
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Climate Change-Induced Drought Causing Crop Failure, Livestock Problems in Indian Himalayas
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