Nemasphere Offers New Tool Against SCN

Biotech Trait From BASF Provides Novel Resistance Against Soybean Cyst Nematode

Jason Jenkins
By  Jason Jenkins , DTN Crops Editor
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Michael McCarville, BASF trait development manager, introduced Nemasphere, the company's transgenic Bt trait for SCN resistance, to a group of agricultural journalists at an event in North Carolina in May. (DTN photo by Jason Jenkins)

RESEARCH TRIANGLE PARK, N.C. (DTN) -- Eight years after its initial discovery, a transgenic trait for combating soybean cyst nematode (SCN) now has a trade name. BASF announced on Monday, June 10, that the trait for expressing the protein, Cry14Ab-1, will be called Nemasphere.

While the company still doesn't expect Nemasphere to be available until 2028, BASF touts it as the first and only biotechnology trait for SCN, the No. 1 yield-robbing pest in soybeans in the United States. Annually, the parasitic worm costs farmers $1.5 billion, according to The SCN Coalition, a public/private/checkoff partnership formed to encourage growers to actively manage the nematode.

"We've not had a new major trait launch in [SCN resistance] in over 60 years," said Michael McCarville, BASF trait development manager, during a media event held in May. "Now, we have something for the first time that can provide us a real solution. It is really a generational breakthrough with a novel mode of action that's proven effective against SCN."

PEST PROLIFERATION

SCN's presence in the United States was first detected in North Carolina in 1954. Since then, it's been found nearly everywhere soybeans are grown. The plant-parasitic nematodes feed on soybean roots, inhibiting plant growth and reducing root function.

Above ground, this damage is not distinctive and may not appear until infestations reach extremely high levels. In fact, yield losses of up to 30% to 50% can occur without any visible symptoms, said Horacio Lopez-Nicora, a soybean pathologist and nematologist at Ohio State University.

Researchers began identifying and developing useful varieties almost immediately after SCN was first detected. Plant introductions containing native SCN resistance -- most notably, PI 88788, and to lesser degree, Peking (PI 548402) -- were utilized in most commercial soybean lines.

Yet, like weeds developing resistance to herbicides, SCN has overcome these native sources.

"If you look at a map of the Midwest, the vast majority of SCN populations that you find in the field will readily reproduce on PI 88788," McCarville said. "Over 98% of varieties for a long period of time were PI 88788. Today, 87% of the varieties are PI 88788. So everybody's doing the same rotation, growing the same source of resistance. And we did this for 20 years."

He said that in the early 2000s, a soybean grower could expect better than 90% control of SCN when growing a variety containing PI 88788. On average today, that control is down to 60% and will likely erode to less than 50% by the end of the decade, he said. As control decreases, SCN's negative effect on soybean yields increases.

Despite soybean breeding advances that continue to increase average national yield by better than 0.5 bushels per acre (bpa) year after year, SCN's increasing tolerance to native resistance has outpaced it. Lopez-Nicora likened it to the Red Queen's race from Lewis Carroll's classic, "Through the Looking-Glass": "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!"

"In the early 2000s, yield loss to SCN averaged 4% or 2 bpa. Most people would say, 'I can probably live with that,'" McCarville said. "By the mid-2010s, it was 5.5 bpa or 9%. By the end of the decade, we're looking at double digits for bushels, and we will eclipse 10% yield loss.

"I had a nematologist from Brazil who explained it to me as that's one out of every 10 soybean crops," McCarville continued. "Nine soybean crops go to your family and to people to feed them. One is feeding nematodes. This is a herd of cattle that they don't realize they're raising, and it's really expensive to raise."

TRAIT TARGETING SCN

While transgenic Bt trait technologies previously have been employed to control insect pests in corn and soybeans, a novel Cry14 protein to target plant-parasitic nematodes is new. However, the premise is the same. The bacterium-derived trait produces a protein that when ingested by the nematode eventually leads to its death.

"The Cry14 is agnostic," said Julia Daum, BASF senior program leader who led the team that discovered the trait. "It doesn't care if the nematode has developed resistance to PI 88788 or not. It's going to kill all of them by poking holes in their gut."

Daum said that in addition to SCN, the Cry14Ab-1 protein is also effective on several other plant-parasitic nematodes, yet it doesn't pose a threat to free-living nematodes or other animals, including humans.

Unlike insect Bt traits, Nemasphere won't require growers to establish a refuge or purchase seed with the refuge "in the bag."

"Nemasphere will be stacked with native resistance," McCarville explained. "So, from a resistance management plan and best practices, everything that The SCN Coalition talks about today would still apply. If you have Nemasphere-PI 88788 and Nemasphere-Peking varieties, you can still do your rotation and get your optimal yield and your durable strategy.

"Traits pay twice," he said. "More yield this year, less risk in the future because you're actually going to drive down indices and populations. You're going to reduce your future risk from this pathogen."

YIELD TRIALS AND TIMELINES

The first in-field trials with soybean plants containing Nemasphere were planted in 2017 near Eagle Grove, Iowa. BASF began breeding the trait into its germplasm in 2019, said Jesse Gilsinger, North American soybean breeding manager. Across the Midwest in 2023, the company evaluated the first wave of soybean lines that included traits for both Nemasphere and Enlist E3 herbicide technology.

"We were really pleased with how these materials looked in the field," Gilsinger said. "Many of the selections were performing greater than 108% of the commercial check mean yield. We have some lines that were 112% to 114% of the check mean, so we're really excited about the data we're looking at there.

"The very best of those will get moved to advanced stage yield testing this year," he continued. "These would be the first wave of products, by late decade."

Gilsinger said that adding the Nemasphere trait offers a second layer of protection against SCN.

"It's kind of like a concrete floor. If you pour a concrete slab that's 2 inches thick, you probably don't want to drive your car on it," he said. "But if you make it just twice as thick -- 4 inches -- you can probably drive a tractor on it and be just fine. It's the same with germplasm and traits. You combine those, and in the end, you get a much stronger product."

Pending regulatory approval, BASF expects to make Nemasphere available to select growers in 2028. The first varieties available will be Group 2.5 to Group 4.5, said Bryan Perry, BASF U.S. head of seeds and traits.

Caroline Currie, BASF North American strategic marketing lead for seeds and traits, said they anticipate an initial launch of 50,000 acres in the U.S. with preferred Xitavo growers. A full-scale commercial launch is expected in 2029.

In 2022, BASF announced a licensing agreement with Corteva and MS Technologies for developing Enlist E3 soybeans with Nemasphere. Read more here: https://www.dtnpf.com/…

More from DTN on this trait: https://www.dtnpf.com/…

To read even more about managing soybean cyst nematode, read the Summer 2024 issue of Progressive Farmer, available here: https://www.dtnpf.com/…

Jason Jenkins can be reached at jason.jenkins@dtn.com

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Jason Jenkins