Soybean cyst nematode (SCN, Heterodera glycines) is the most destructive pathogen of soybean and widely spread in Minnesota and most soybean growing regions throughout the world. In the USA, annual soybean yield loss to SCN has been estimated around 1 billion US dollars. Recently, a new cyst nematode species, Heterodera sojae, also known as ‘white soybean cyst nematode’ (WSCN), was found in Korea. In a later survey, WSCN was detected in about 28% of soybean fields in Korea and it concomitantly occurred with SCN in many soybean fields making management difficult. The WSCN also can cause severe damage to soybean and is another threat in soybean production in Korea. WSCN has also been detected in China, indicating a possibility that the nematode also exists in other regions in the world.
Management options for the SCN include use of host resistance, cultural practices mainly crop rotation and soil fertility management, and chemical and biological controls depending on cropping systems and environmental conditions in a region, but host genetic resistance is the most important. Most soybean fields in the north central USA are planted to SCN- resistant soybean cultivars. Breeding and deployment of SCN-resistant cultivars, however, are challenging due to the genetic variability of SCN, the selection pressure on SCN when resistance is used, and the linkage of yield-suppressive factors with SCN-resistance genes in the current available sources of resistance. Despite a number of soybean germplasm lines have been found resistant to SCN, only limited sources of SCN resistance have been deployed in commercial soybean cultivars. The SCN resistance in most (approximately 95%) current commercial cultivars in the north central USA is from the germplasm line PI 88788, and only a few from the germplasm lines Peking, and others. With the extensive use of the limited sources of resistance, most SCN populations in Minnesota have evolved to overcome the resistance in the commercial cultivars. Changes in virulence phenotypes, measured as races or HG Types of SCN populations following the use of resistant soybean cultivars have been demonstrated with field plot experiments, as well as state, regional, and national surveys.
The level of SCN resistance depends on the interaction between host (soybean) and SCN genetics. The genetics of SCN resistance in soybean has been extensively studied and a number of QTLs (locations of genes on chromosomes) containing SCN-resistance genes have been identified. For examples, the rhg1 and Rhg4 are two QTLs commonly used in most current SCN-resistant soybean cultivars, and the genes in the two QTLs have been identified. However, little is known about the molecular mechanisms of the virulence of SCN populations on different sources of resistance. Studies have demonstrated that there are numerous genotypic and virulence-phenotypic variations among SCN populations and within a population. There are also variations of SCN morphology among individuals even within a field SCN population. Whether or not the variations in morphology are associated with SCN virulence phenotype are unknown. There is a possibility that some variations in cyst nematode populations are actually due to mixture of SCN and WSCN.

Our knowledge of SCN virulence is generally based on an SCN population with mixed phenotypes. For accurate measurement of SCN resistance in soybean, SCN populations homogenous in genetics are highly useful. We have developed a total of 180 SCN inbred lines randomly selected from about 100 SCN field populations ‘randomly’ collected across Minnesota soybean growing counties in 2013. The individuals in each of the inbred lines are homogenous in genetics and are highly valuable for studies of SCN genetics, host resistance, and soybean breeding. The 180 randomly selected SCN inbred lines can represent the diversity of SCN in Minnesota, and they are excellent resources for study of SCN diversity in the state. In addition, the inbred cyst nematode lines are highly useful resource for detection of WSCN. Early detection of the nematode is important for strategically breeding soybean cultivars resistant to both cyst nematode species.
We initiated this project in 2021 with first-year funding from MSRPC. In this project, we will characterize the virulence phenotypes of the 180 inbred cyst nematode lines on the SCN-resistant soybean germplasms used or potentially used in the University of Minnesota breeding program, and detect WSCN among the 180 inbred cyst nematode lines. In addition, we will include our long-term study of effect of SCN-resistance sources on SCN population virulence phenotypes. This research is important for strategically deploying host resistance for managing the cyst nematodes in soybean. The ultimate outcome will be the increase of soybean profitability for soybean growers in Minnesota and other regions.
A student was hired in the fall of 2021 to study the diversity of the SCN populations. Currently, we are phenotyping the SCN populations for their virulence (HG Types). So far we have finished virulence test (HG Type test) about 35 SCN populations. The student is working on nematode DNA extraction. In this proposal, we request the second year of funding mainly to support the student and a technician to continue the research.

1. GOAL : Determine diversity of SCN virulence phenotypes in Minnesota

OBJECTIVE : Characterization of virulence phenotypes of SCN inbred population.
In this objective, we will characterize virulence phenotypes of 180 SCN inbred lines. Specifically, (1) the reproduction potential measured as female index (FI) of the nematode lines will be determined on the SCN-­-resistance sources used in the University of Minnesota breeding program; (2) the data will be used to analyze the diversity of SCN in Minnesota.


2. GOAL : Determine if white soybean cyst nematode occurs in Minnesot

OBJECTIVE : Study of variations of SCN morphology and detection of white soybean cyst nematode. In this objective, In this objective, we will study the morphology and sequence DNA of the 180 inbred
SCN populations to identify if all of these lines belong to SCN and if any of the lines is WSCN. In addition, we will analyze if any of the morphological parameters associated with virulence phenotype.
3. GOAL : Predict the changes of SCN virulence phenotypes following the use of different sources of SCN-­- resistance
OBJECTIVE : Determine the effect of sequences of SCN-­-resistance sources on SCN population densities and virulence phenotypes
In this objective we will determine: (1) the effect of various sequences of three important sources of resistance PI 88788, Peking, and PI 437654 on the SCN population dynamics in a field initially infested by SCN race 1; (2) the effect of the sequences on change of SCN virulence phenotypes in the field.

• This project will develop knowledge of diversity SCN virulence (HG Types) in Minnesota, and the knowledge will be used to strategically deploy effective types of SCN resistance in soybean cultivars.
• This project will determine if white soybean cyst nematode, another important cyst nematode on soybean, occurs in Minnesota.
• The study will result in a better understanding of basic biology of the soybean cyst nematode.
• The information developed from this project will be used in extension education such as Agronomy Field Tour, Open House at the University of Minnesota Southern Research and Outreach Center, and MN Ag Expo.
• The research will be published in scientific journal for a broader dissemination.

Update:
Summary: The soybean cyst nematode (SCN, Heterodera glycines) is the most destructive pathogen of soybean and widely spread in Minnesota and most soybean-growing regions throughout the world. Recently, a new cyst nematode species, Heterodera sojae, also known as ‘white soybean cyst nematode’ (WSCN) as a common name, was found in Korea and China. Soybean cyst nematode has big variations in morphology and virulence phenotypes (ability of reproduction on different soybean germplasm lines). In this project, we will study diversity of the SCN and detect WSCN in Minnesota. Specifically, we will phenotype 184 inbred lines of cyst nematodes for their virulence phenotypes on the SCN-resistant source germplasm lines PI 88788, Peking, PI 548988, PI 90763, PI 567516C, PI 438489B, and two lines that have novel SCN-resistance QTL/gene. We will study variations in SCN morphology and determine if WSCN occurs in Minnesota or not. So far, 38 SCN lines have been phenotyped for their virulence on the eight soybean lines and additional 135 SCN lines on PI 88788 and Peking.
In an on-going field experiment, the impact of rotation of soybean cultivars with different sources of resistance on SCN virulence is studied. The experiment was established in 2008. SCN population densities were or will be determined at planting and harvest every year. Virulence phenotypes of SCN were determined in 2008, 2011, 2013, and 2017, and 2020, and will be determined again in 2022.
See the attached file for details.

View uploaded report

Update:
Summary: The soybean cyst nematode (SCN, Heterodera glycines) is the most destructive pathogen of soybean and widely spread in Minnesota and most soybean-growing regions throughout the world. Recently, a new cyst nematode species, Heterodera sojae, also known as ‘white soybean cyst nematode’ (WSCN) as a common name, was found in Korea and China. Soybean cyst nematode has big variations in morphology and virulence phenotypes (ability of reproduction on different soybean germplasm lines). In this project, we will study diversity of the SCN and detect WSCN in Minnesota. Specifically, we will phenotype 184 inbred lines of cyst nematodes for their virulence phenotypes on the SCN-resistant source germplasm lines PI 88788, Peking, PI 548988, PI 90763, PI 567516C, PI 438489B, and two lines that have novel SCN-resistance QTL/gene. We will study variations in SCN morphology and determine if WSCN occurs in Minnesota or not. So far, 42 SCN lines have been phenotyped for their virulence on the eight soybean lines and additional 142 SCN lines on PI 88788 and Peking. DNA of 175 lines has been extracted.
In an on-going field experiment, the impact of rotation of soybean cultivars with different sources of resistance on SCN virulence is studied. The experiment was established in 2008. SCN population densities were or will be determined at planting and harvest every year. Virulence phenotypes of SCN were determined in 2008, 2011, 2013, and 2017, and 2020, and will be determined again in 2022. The field soil samples in 2022 have been collected, and soybean yield have been recorded. Greenhouse bioassay has been set up for HG Type test.
See the attached for details.

View uploaded report

Update:
Summary: The soybean cyst nematode (SCN, Heterodera glycines) is the most destructive pathogen of soybean and widely spread in Minnesota and most soybean-growing regions throughout the world. Recently, a new cyst nematode species, Heterodera sojae, also known as ‘white soybean cyst nematode’ (WSCN) as a common name, was found in Korea and China. Soybean cyst nematode has big variations in morphology and virulence phenotypes (ability of reproduction on different soybean germplasm lines). In this project, we will study diversity of the SCN and detect WSCN in Minnesota. Specifically, we will phenotype 180 inbred lines of cyst nematodes for their virulence phenotypes on the SCN-resistant source germplasm lines PI 88788, Peking, PI 548988, PI 90763, PI 567516C, PI 438489B, and two lines that have novel SCN-resistance QTL/gene. We will study variations in SCN morphology and determine if WSCN occurs in Minnesota or not. So far, 60 SCN lines have been phenotyped for their virulence on the eight soybean lines and additional 116 SCN lines on PI 88788 and Peking. DNA of the 180 lines has been extracted.
In an on-going field experiment, the impact of rotation of soybean cultivars with different sources of resistance on SCN virulence is studied. The experiment was established in 2008. SCN population densities were or will be determined at planting and harvest every year. Virulence phenotypes of SCN were determined in 2008, 2011, 2013, and 2017, and 2020. In 2022 soil samples were collected and soybean yield recorded. Soil samples will be processed for SCN egg counts. Greenhouse bioassay has been performed for HG Type test. First rep of HG Type test samples has been processed.
See the attached for details.

View uploaded report

Update:
The soybean cyst nematode (SCN, Heterodera glycines) is the most destructive pathogen of soybean and widely spread in Minnesota and most soybean-growing regions throughout the world. Recently, a new cyst nematode species, Heterodera sojae, also known as ‘white soybean cyst nematode’ (WSCN) as a common name, was found in Korea and China. Soybean cyst nematode has big variations in morphology and virulence phenotypes (ability of reproduction on different soybean germplasm lines). In this project, we are studying diversity of the SCN and detecting WSCN in Minnesota. Specifically, we plan to phenotype 178 inbred lines of cyst nematodes for their virulence phenotypes on the SCN-resistant source germplasm lines Pickett, Peking, PI 88788, PI 90763, PI 834489B, and PI 567516C. We study variations in SCN morphology and determine if WSCN occurs in Minnesota or not. So far, 86 SCN lines have been phenotyped for their virulence on the eight soybean lines and additional 92 SCN lines on PI 88788 and Peking. Genomic DNA of the 177 lines has been extracted, and the genomes sequenced.
In an on-going field experiment, the impact of rotation of soybean cultivars with different sources of resistance on SCN virulence is studied. The experiment was established in 2008. SCN population densities were determined at planting and harvest every year. Virulence phenotypes of SCN were determined in 2008, 2011, 2013, 2017, 2020, and 2022.
See the attached for detailss.

View uploaded report

Update:
This project has been extended to 2024.