Fast-Track Traits
By Wayne Wenzel
Published: March 17, 2007 (Farm Journal)
Genetically modified (GM) corn and soybeans have captured headlines in recent years, but the next biotechnology revolution is quietly transforming grain sorghum, rice and canola into the crops of the future.
The catalyst for this change is a new method of engineering plants. Developed by Cibus, a small biotech startup in San Diego, the technology is called Rapid Trait Development System (RTDS™;). Not only does RTDS™ promise many of the benefits of genetic modification, but it does so without inserting foreign genes.
One of the first RTDS™ products expected to reach farmers’ fields is a sorghum trait with a high tolerance to Valent’s postemergence grass herbicide, Select Max. Tolerance to the herbicide’s active ingredient, clethodim, promises to notably increase the productivity and profitability of sorghum farming by adding another grass herbicide option to control grass weeds.
A recent Kansas State University survey of more than 600 U.S. sorghum producers identifies grassy weed control as the No. 1 research priority.
Sorghum catches up. In the current world of gene-inserted biotech trait development, corn gets most of the corporate research attention with 35 unique GM event approvals worldwide. Canola has 14 GM traits, and rice has two. Sorghum, once a widely preferred crop in the arid High Plains, has gone lacking for many years.
Bruce Maunder, president of the National Grain Sorghum Producers Foundation (NGSPF) and former sorghum research director and breeder for DeKalb, says Cibus was specifically asked to resolve this problem. “The sorghum industry has been in transition as it continues to consolidate into a few large players,” Maunder says.
“Although we have good working relationships with the major seed companies, sorghum is a low priority for the application of biotechnology resources,” he says.
“Current grass-control options for sorghum are incomplete and expensive. Since we grow sorghum under less rainfall than other crops, the competition from weeds causes even greater losses because the weeds have a tendency to go after that moisture faster than the sorghum,” Maunder adds.
RTDS™ could be particularly beneficial to lower-acreage crops like sorghum because it bypasses the international thicket of regulations that hinder, and sometimes prevent, GM crops from ever reaching the marketplace.
Keith Walker, Cibus president, says USDA has agreed that RTDS™ is considered a “mutational technology” and traits developed by it are free of regulations that apply to transgenics.
“We start with what nature gives us in the plant. Then, we make very small, targeted changes to key genes of interest,” Walker says. European Union regulators specifically exclude processes derived from mutational technologies as exempt from the GMO Directive, Walker adds.
Basic science. RTDS™ is like a refined version of mutagenesis, a process that plant breeders have used for a number of decades. For example, to create imidazolinone herbicide-tolerant Clearfield corn, wheat, canola and rice varieties, scientists began by bathing seeds in a chemical that induces changes in gene sequences (mutations). Plants grown from these seeds are sprayed with imidazolinone herbicide. The surviving plants contain the trait for herbicide tolerance.
Other crops that are engineered to produce healthier oils or specific proteins have relied on a similar mutagenesis process and have avoided being branded by regulators as genetically modified organisms.
Traditional mutagenesis processes randomly change or mutate plant genes and require laborious sifting through tens of thousands of samples for useful new traits. The benefit of RTDS™ is it is faster and more efficient because it targets a specific gene with a specific change that is predetermined to create the desired outcome. Like mutagenesis, RTDS™ gene tweaks can enhance nutritional value, modify key food-processing characteristics or improve tolerance to specific kinds of herbicides or plant diseases (see “How RTDS™ Works”).
There is significant gene overlap in crops, such as corn, rice and wheat. Many legume crops may have up to 90% of their genes in common. If scientists find a useful trait in one plant, RTDS™ can give it a nudge by using a small sequence of DNA to create desired changes in other crops.
What RTDS™ can’t do is add a trait that nature couldn’t otherwise create in a plant. “I don’t think we’re going to replace the current biotech trait industry anytime soon,” Walker says. “What we can do is make the benefits of the biotech revolution available in more crops and to more farmers.”
RTDS™ could work for corn, as well. But, given the savings in time and money ($30 million to $50 million per gene insertion trait event compared with $3 million to $5 million for RTDS™), Cibus will focus first on smaller-acreage crops where foreign gene insertion is unlikely to be cost effective.
The strategy also avoids direct competition with biotech giants, such as Monsanto Company and Pioneer Hi-Bred International, while giving growers of smaller-acreage crops biotech- based management tools designed to improve production practices and increase crop yields. In addition to sorghum, Cibus plans to offer RTDS™-engineered herbicide-resistant canola and rice by 2010.
How RTDS™ Works
Rapid Trait Development System (RTDS™) is a site-directed mutagenesis process that uses the plant’s own genetic machinery to change its DNA. This is standard practice for engineering bacteria, but Cibus in San Diego, is the first company to develop a fast and reliable way of applying it to plants.
Conventional genetic engineering takes exotic genetic material from one species and inserts it into another. RTDS™ introduces genetic traits through a process of gene repair within the same plant species.
“RTDS™ operates exclusively within the genome of the plant and eliminates environmental and health risks perceived to be associated with GMO [genetically modified organisms] crops,” says Cibus president Keith Walker. “If you could look at a gene under a high-powered microscope, you’d see something that looks like a ball of yarn that has been unwound and then bunched up. We only change a small part of that with RTDS™.”
When scientists first started manipulating crops like corn, they used a gene gun to shoot microscopic metal pellets coated with long strands of DNA into the plant cell’s nucleus. Not surprisingly, blasting long strands of DNA into a tangled ball of more DNA gave inconsistent results.
RTDS™ works with shorter fragments of DNA and targets specific gene sequences. No foreign genes are inserted. Cibus technology produces changes in a plant species that could occur in nature but does it in a directed, accelerated way.
