Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-046-049-I
Project Type: Interagency Reimbursable Agreement
Start Date: May 1, 2024
End Date: Sep 30, 2024
Objective:
The objectives of this research are targeted towards reducing the risk of introduction so of new potato cyst nematode (PCN) pathotypes into the United States. Specific objectives include:
1. Identify unique resistance sources for PCN from South America.
2. Identify PCN virulence factors and genomics.
Approach:
Objective 1: Plants with resistance to PCN will be screened against G. ellingtonae. Material from Peru and Chile has been shipped to the U.S. under an USDA-APHIS permit which allows for screening and then destruction of the material. We will first use the 57R PCR marker to determine if the material carry the H1 gene at U of Idaho). Polymerase chain reaction of 57R will allow us to quickly determine what material is resistant to G. rostochiensis from the H1 gene, a source that is already widely utilized. The material that does not carry the H1 gene will be further screened for resistance to G. ellingtonae. Our previous work has demonstrated that many varieties of potato that carry the H1 gene are also resistant to G. ellingtonae (Whitworth et al., 2018). By screening non-H1 material we may be able to find novel resistance genes to G. rostochiensis and G. ellingtonae. Marker assisted selection of all of the material will allow us to decide which material should be screened for resistance to the G. pallida population in Idaho. Established techniques used in the Zasada lab will be used to conduct screenings. Material from South America will be grown in 3-inch pots and inoculated with 2,000 nematode eggs when they reach 20 centimeter in height. Susceptible potato varieties, such as ‘Désirée’ and ‘Russet Burbank’, will also be included as controls. Plants will be harvested approximately 3-4 months after nematode infection and nematode cysts will be extracted from air-dried soil. A final nematode egg count will be obtained to determine if individual plants confer broad-spectrum resistance to multiple Globodera species. The experimental units will be arranged in a complete randomized design with genotypes being replicated four to five times. Reproduction factor values (RF) will be calculated as (final egg density/initial egg density) x 100. ‘Désirée’ will be used as the standard to calculate relative susceptibility values (RS) (final egg or cyst density of test variety/final egg or cyst density on ‘Désirée’) x 100 (EU, 2007).
Objective 2: Populations of PCN collected from South America will be genetically characterized. First, genotype-by-sequencing (GBS) will be applied to all collected populations. This method yields thousands of single nucleotide polymorphisms (SNP) in a genome and allows for the study of the relationship between populations of different origins or pathotypes. Once a clear separation among collected populations is obtained by GBS, the entire genomes of selected populations representing different pathotypes will be sequenced. This data will then be mined to retrieve effector (genes that target host pathways to facilitate parasitism) sequences and to compare the diversity of these sequences with an eye on how PCN interact with their host. It will also be used to identify addition SNP that exist between populations.
