Bacteria Gene Inserted in Corn to Make it More Drought Tolerant

Drought resistant corn is coming soon. It’s the latest transgenic offering from the Monsanto seed company. After the US Department of Agriculture chose not to regulate DroughtGard, a new species of genetically engineered corn late last year it means the new crop will move from its current test phase into commercialization this year.

DroughtGard Corn from Monsanto, courtesy of Monsanto

DroughtGard Corn from Monsanto, courtesy of Monsanto

But what’s in the corn that makes it more resistant to drought? It’s a gene called cold shock protein B or cspB that comes from a common bacteria. It is called the Bacillus subtilis bacteria, also known as hay or grass bacillus, commonly found in soil. The gene facilitates protein function. The seed giant also added a second foreign gene that codes for antibiotic resistance.

According to Monsanto in the case of corn, “CspB works by helping the plant maintain growth and development during times of inadequate water supply. A corn plant is particularly vulnerable to drought during reproductive growth stages. By mitigating the impact of drought on the plant, cspB helps provide yield stability. Improved yield stability is of significant value to farmers faced with unpredictable rainfall.”

Monsanto worked with European chemical company BASF to develop the first biotechnology-derived drought-tolerant crop in the world. They made the initial discovery in 2009 but it’s taken several years of regulatory scrutiny and testing to bring it to the farmers in drought-stricken parts of the U.S.

In a 2010 biotechnology note the FDA, which regulates food additives, said, “Monsanto describes the CSPB protein produced in corn event MON 87460 as identical to the native CSPB protein produced in B. subtilis except for one amino acid introduced for cloning purposes. Bacterial cold shock proteins (CSP) are hypothesized to function by binding to RNA secondary structures, thus reducing the free energy required for unfolding misfolded RNA. CSPs are classified as RNA chaperones. Monsanto notes that similar cold shock domain-containing proteins are also present in plants where they appear to play a role in conferring stress tolerance.”

CsbB Protein at Work in Monsanto Genetically Modified Corn

CsbB Protein at Work in Monsanto Genetically Modified Corn, courtesy of Monsanto

The FDA noted that Monsanto found several polypeptides containing at least 8 amino acids that could express proteins. The company ran those sequences against databases of any known toxins or allergens and found they didn’t match any. Then the FDA reports that it tested both bacillus subtilis and the cspB protein for safety and toxicity.

Previous research shows that b. subtilis is commonly used as a food additive with no deleterious effects, thus answering the safety question. And additional research shows that the cspB protein bears no similarity to proteins known to be toxic or bioactive.

Speaking on behalf of the agency, Susan Carlson said, “Based on the information provided by the company and other information available to the agency, FDA did not identify any issues under Sections 402 and 409 of the Federal Food, Drug and Cosmetic Act that would require further evaluation at this time.” She felt that Monsanto had satisfied their obligation to determine if its intended genetic modification of corn posed any risk.

Before the FDA gave its approval for Monsanto to move forward with its testing and commercialization of drought-resistant corn, Dr. Shenaz Moola from the African Centre for Biosafety raised a few objections (PDF).

He says, “Inserted gene sequences may interrupt native gene sequences and/or their promoters and additional code fragments are not necessarily non-functional and may be transcribed.”

He cites Monsanto’s product Roundup Ready Soy which was supposed to have gene fragments that were “non-functional and not-transcribed.” Later they were found to transcribe and produce RNA. He says, “Unintended effects that are not detected in the lab and that may only become apparent in the long term cannot be ruled out.”

The antibiotic resistance marker gene nptII from E.coli is also part of the drought-resistant corn DNA. That gene codes for an enzyme that makes the organism (in this case the corn) resistant to three common families of antibiotics.

Dr. Moola doesn’t know why Monsanto and BASF even put that gene into the drought-resistant corn. He says, “In the development of MON 87460 [drought-resistant corn], the residual nptII gene is gratuitous especially since it is bordered by loxP sites and thus could have been removed.”

In a European Food Safety Authority statement (PDF) Monsanto says its antibiotic resistance markers have “no adverse effects on human health and the environment.

Not everyone agrees.

Two senior members of the EFSA’s biohazard panel that reviewed Monsanto’s application for use of drought-tolerant corn say, “adverse effects cannot be assessed” and the probability of gene transfers from plants to bacteria ranges widely “from unlikely to high.”

Dr. Moola says the evolution of antibiotic resistance is a clear indicator of gene transfer frequency, since antibiotics have been used in medicine for about 50 years. He is concerned about horizontal gene transfer where genes transfer genetic material between organisms, outside the context of parent to offspring reproduction. Most of the time it is performed through infectious transfer where the genetic material is transported by a bacteria or virus.

He says, “The intentional modification of plants could through horizontal gene transfer result in the unintentional modification of other organisms.”

This is already widely seen in pollination events where genetically modified plants are interbreeding with non-GMOs.

DroughtGard Field Test Map, 2010, courtesy of Monsanto

DroughtGard Field Test Map, 2010, courtesy of Monsanto

But the new DroughtGard variety of corn is already in the ground. For the last three years over 200 test sites throughout the Midwest have been planting the transgenic corn next to unmodified corn to measure the difference.

During its testing phase Monsanto has shifted its effort from a drought-resistant variety ideal for the parched Earth of Africa to a drought-tolerant variety that just boosts yields a bit under stressed water conditions.

And for the last couple of years the corn belt in Kansas and Nebraska have feel the full force of drought conditions as corn yields dropped under unusually dry conditions. During these times the DroughtGard corn performed well compared to non-GMO corn.

According to a United Nations’ Food and Agriculture Organization report prepared for ministers of the G-8, the number and duration of dry spells, especially in already drought-prone areas, is expected to increase.

Monsanto and its line of drought-resistant crops is banking on that. Over the next ten years it hopes to roll out a series of genetically modified plants that will all have foreign genes inserted into the seed’s DNA to make it more drought tolerant and make the company an additional $300 million to $500 million a year.

In December when the FDA decided not to regulate the new Monsanto corn variety, it marked the first time the US Department of Agriculture’s Animal and Plant Health Inspection Service approved a product that is genetically modified to resist drought, instead of a pest or fertilizer.

The agency concluded that the corn is is unlikely to harm the environment, people or animals and wouldn’t boost corn production at the expense of grasslands and forest.

Doug Gurian-Sherman
from the Union of Concerned Scientists’ Food and Environment Program says, “There’s no reason to think the corn might be unsafe.” But he and Bill Freese at the Center for Food Safety wish there were more stringent testing and regulation of crops produced with biotechnology.

Share
Share This Post On

Submit a Comment

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>