SCN Breakthrough Excites Researchers

More work needed to go from discovery to application

New plant-resistance discoveries excite both researchers and farmers at the prospect of finding solutions to yield barriers in soybean production.

One of those barriers, the soybean cyst nematode (SCN) pest, has been at the forefront of research recently. In fact, some researchers think that a new finding in plant-parasitic nematodes may be the future in fighting the pests.

Photo: United Soybean Board

Researchers at the University of Missouri, with the help of researchers at the University of Bonn in Germany, have found the first genetic evidence that nematodes use a specialized plant hormone, called cytokinin, that enables them to attack agricultural crops. They believe this could be the first step in developing soybean varieties that are resistant to nematode pests.

More durable resistance

“This is certainly a great finding and important for future development of new SCN-resistant crops using molecular technology,” says Senyu Chen, University of Minnesota (UMN) professor of plant pathology and nematology. “If we can manipulate cytokinin levels in soybeans to limit SCN parasitism without suppressing plant growth, this will be certainly an additional method – perhaps a key method – for SCN management.”

Chen also points out that a better understanding of nematode genes that interact with the resistance genes in soybeans can provide better ways to use the natural SCN-resistance genes for control of the pest.

“Our collaborative research in the past years has resulted in discovery of more SCN-resistant soybean lines and potential novel genes,” Chen says. “We are using these new sources of resistance to breed new SCN-resistant cultivars. The effectiveness and durability of SCN-resistant cultivars will increase.

“In addition, I also have collaborative research to study how SCN populations interact with soil microbial organisms in different cropping systems,” he adds. “We hope the information will help farmers manipulate the field soil to reduce SCN population densities.”

Efficient breeding

Chen also works with UMN Professor of Plant Genomics and Disease Resistance Nevin Young to develop varieties with stable SCN resistance and attributes like yield, high protein, iron chlorosis tolerance, resistance to other diseases and pests, glyphosate tolerance and food-type beans.

“We were the first to map the most important SCN resistance gene, Rhg1, using DNA markers, and the first to develop markers that could be used routinely in breeding programs,” Young says. “Today, we are able to screen thousands of progeny lines from SCN crosses as this process has become automated and optimized.”

Plenty of work ahead

Despite the advancements, SCN has slowly been overcoming existing forms of resistance, including the Rhg1 gene. This has led the team to explore novel sources of resistance in order to expand grower options with the hopes of providing soybean varieties with more durable resistance to SCN in the future. Young notes it’s a significant challenge to go from basic discovery to practical application.

Courtesy Minnesota Soybean Research & Promotion Council