Research Highlights

Research Highlights
Developing Another Tool to Fight Soybean Cyst Nematode in the Field

Left to right: Assistant Professor Lei Zhang, undergraduate lab assistant Marilyn Vargas, and Lin Ye, a Ph.D. student in Zhang’s lab, display the portable PCR machine that could be used in the field to test SCN population density and hatch potential. This machine can reveal results in within a day, far faster than traditional testing that takes weeks. Photo courtesy Lei Zhang

By Carol Brown

Many researchers across the country are working on behalf of farmers to find solutions to the issues created by soybean cyst nematode, or SCN. Agronomists are exploring field management practices that reduce the spread of SCN such as crop rotations and cover crops. Geneticists and breeders are developing new soybean varieties with SCN resistance in their genetic makeup. Others are supporting both aspects of research to aid in genetic development and to reduce in-field populations.

Lei Zhang, an assistant professor of botany and plant nematology at Purdue University, is leading a research project that could benefit both scientists and farmers. The project, supported by the Indiana Soybean Alliance, focuses on SCN hatch potential through nematode genetics.

“With this project, we are looking at molecular markers that can determine how well SCN eggs will hatch. We want to develop an on-farm tool that can identify SCN population density and hatch potential,” says Zhang. “We have identified candidate SCN genes through RNA-sequencing that may be good indicators for higher or lower egg hatch potential. We have been conducting tests in the lab and in greenhouse conditions for confirmation.”

Some crops are SCN hosts such as dry beans and a few cover crops including clover and hairy vetch. Other crops are considered non-host crops for this pest, and non-host crop rotation is a way to control SCN. When the SCN eggs hatch into a non-host crop, there isn’t food available for them, so the nematodes die and their populations decline in the soil. However, if SCN egg numbers are high at the end of the soybean growing season, a rotation with a non-host crop may not reduce SCN populations effectively, says Zhang. SCN eggs can remain dormant and viable in the soil for several seasons and when soybeans are grown in the field again, the SCN eggs sense the presence of soybean roots and hatch to infect the plant. By finding a way to evaluate SCN egg hatch potential, farmers can use this information to make field-level decisions.

“For example, if farmers have an idea that the potential of SCN hatch is high, then planting a non-host crop will be crucial and effective to help reduce SCN population density. With this information, farmers can be cognizant of planting a non-host crop, like corn, and not another host crop within their rotation,” he explains. “Of course, environmental conditions, such as soil moisture and temperature, can affect hatch potential, as it can be variable among different years and different fields.”

Currently, finding SCN hatch potential through a hatch assay in a lab takes up to three weeks and is labor-intensive, and therefore costly. Locating molecular markers within the nematode genes can help to speed up this lengthy process, determining the potential in a day or less. This could be good news for fellow researchers as well as farmers.

“We want to develop a tool that is portable, that can be used in the field,” says Zhang. “A retail agronomist or extension specialist could conduct the test through soil sampling and have diagnostics completed within a day or sooner.”

The portable machine Zhang is working on uses polymerase chain reaction, or PCR, technology to test soil samples in the field for SCN population density and hatch potential. This technology may sound familiar, as it is used when testing for the COVID-19 virus in humans.

But first, Zhang needs to ensure the SCN hatch potential genetic markers and genes associated with SCN hatch are accurate. The team ran the newly developed diagnostic analysis on SCN samples in the lab, then on SCN propagated in their greenhouse. They compared results with traditional methods of evaluating SCN hatch potential with positive outcomes. This coming crop season, Zhang will expand the testing of both the genetic markers and the portable machine in research plots under real growing conditions. 

Zhang says the on-farm diagnostic test can be done similarly to traditional SCN testing. Either before planting or after harvest are appropriate times to take soil samples for both detection of SCN in the field and for his SCN hatch potential test. Making this technology available to find out hatch potential quicker and for less cost can provide answers for farmers and crop consultants to help make field-level management decisions.

“By doing this diagnosis, it can provide an estimate of the abundance and hatch potential of soybean cyst nematode in the field,” says Zhang. “Growers can compare this with their threshold numbers to help decide what should be grown in rotation in each of their fields.”

Published: Mar 11, 2024

The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.