Science Current Events | Science News | Brightsurf.com
 

Newly identified enzymes help plants sense elevated CO2 and could lead to water-wise crops

December 14, 2009

Biologists have identified plant enzymes that may help to engineer plants that take advantage of elevated carbon dioxide to use water more efficiently. The finding could help to engineer crops that take advantage of rising greenhouse gases.

Plants take in the carbon dioxide they need for photosynthesis through microscopic breathing pores in the surface of leaves. But for each molecule of the gas gained, they lose hundreds of water molecules through these same openings. The pores can tighten to save water when CO2 is abundant, but scientists didn't know how that worked until now.

A team led by Julian Schroeder, professor of biology at the University of California, San Diego, has identified the protein sensors that control the response. Enzymes that react with CO2 cause cells surrounding the opening of the pores to close down they report in the journal Nature Cell Biology online December 13.

The discovery could help to boost the response in plants that do not take full advantage of elevated levels of the gas, Schroeder says. "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."

Plants lose 95 percent of the water they take in to evaporation through these pores, also called stoma. Modifying crops to be more responsive to CO2 could help farmers meet demand for food as competition for water increases. In California, for example, 79 percent of water diverted from streams and rivers or pumped from the ground is used for agriculture according to the California Department of Water Resources.

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.

Several types of cells in plant leaves contain carbonic anhydrases, including those responsible for photosynthesis, but Schroeder's team showed that the enzymes work directly within a pair of cells, called guard cells, that control the opening of each breathing pore. By adding normal carbonic anhydrase genes designed to work only in guard cells they were 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."

The action of carbonic anhydrases is specific to changes in CO2, the researchers found. Mutant plants still open their pores in response to blue light, a sign that photosynthesis can begin. And their pores also shut when water is scarce, a response mediated by a plant drought-stress hormone.

Photosynthesis continued normally in the mutants as well, suggesting that altering CO2 sensitivity wouldn't stunt growth - good news if the goal is to engineer drought-resistant crops with robust yields.

But saving water and surviving heat involves a tradeoff for plants: Evaporation of water through the pores also cools the plant, just like sweat cools human beings. If future growing conditions are hotter and drier, as they are predicted to be in some parts of the world, then modifications to the CO2 response will need to be carefully calibrated.

University of California - San Diego


Related Enzymes Current Events and Enzymes News Articles


Bed bugs have developed resistance to neonicotinoids
A new study published in the Journal of Medical Entomology is the first to report that bed bugs have developed resistance to a class of insecticides known as neonicotinoids, or neonics, the shortened name.

Bedbugs develop resistance to widely used chemical treatments, rendering them ineffective
One of the most of the most widely used commercial chemicals to kill bedbugs are not effective because the pesky insects have built up a tolerance to them, according to a team of researchers from Virginia Tech and New Mexico State University.

Bed bugs that feed are more likely to survive pesticide exposure
Many studies have been done on how effective certain pesticides are when they are applied to bed bugs. However, most have not allowed the bed bugs to take a blood meal after being exposed to pesticides, which can change the mortality rates, according to an article in the Journal of Medical Entomology.

Exact pol(e) position -- precisely where the polymerase is changed
Scientists at the Helmholtz Zentrum München, working with colleagues from the Ludwig-Maximilians-Universität München, have developed a method for the thorough analysis of protein modifications.

Inside the hepatitis C virus is a promising antiviral
A peptide derived from the hepatitis C virus (HCV) kills a broad range of viruses while leaving host cells unharmed by discriminating between the molecular make-up of their membranes, reveals a study published January 5 in the Biophysical Journal.

IU scientists create 'nano-reactor' for the production of hydrogen biofuel
Scientists at Indiana University have created a highly efficient biomaterial that catalyzes the formation of hydrogen -- one half of the "holy grail" of splitting H2O to make hydrogen and oxygen for fueling cheap and efficient cars that run on water.

New guide highlights the properties of diverse drug targets
The new Concise Guide to PHARMACOLOGY 2015/2016 provides a valuable and unique overview of the key properties of more than 1,700 human drug targets, focusing on those exploited currently in the clinic or with future therapeutic potential.

New findings on embryonic heart valves may prevent congenital heart defects in newborns
Cornell biomedical engineers have discovered natural triggers that could reduce the chance of life-threatening, congenital heart defects among newborn infants. Those triggers can override developmental, biological miscues, leading to proper embryonic heart and valve formation.

Improving accuracy in genomic mapping with time-series data
If you already have the sequenced map of an organism's genome but want to look for structural oddities in a sample, you can check the genomic barcode -- a series of distances between known, targeted sites -- by cutting a DNA sequence at those sites and examining the distance between the cuts.

NIH $1.68 M grant funds research to help patients with pancreatitis, diabetes
MUSC researchers received a $1.68 million National Institutes of Health grant to explore a better treatment for chronic pancreatitis, with the hopes that it also may shed light on a future cure for patients with type 1 diabetes.
More Enzymes Current Events and Enzymes News Articles

© 2016 BrightSurf.com