Location: Horticultural Crops Research Unit
Project Number: 2072-22000-043-032-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 15, 2018
End Date: Aug 14, 2020
Objective:
Identify germplasm with resistance to potato cyst nematodes.
Approach:
We have networks in place with scientists from Servicio Agricola y Ganadero (SAG) in Chile and the International Potato Center (CIP) in Peru to aid in the identification of germplasm of interest in their agencies. We will work closely with these entities to select appropriate material for screening and to facilitate the shipment of this material to the U.S. for screening against potato cyst nematodes (PCN). By working with two different countries that encompass both of the proposed origins of potato (Solanum tuberosum) the chance of finding material with resistance to one or all PCN is increased. Additionally, S. tuberosum ssp. andigena, which provided the source of the H1 gene, originates from the Andean region of Chile indicating that other untapped sources of resistance may exist in this diverse germplasm. Solanum germplasm from Peru and Chile has been exposed to Globodera species, and may have developed unique resistances. Our goal is to obtain approximately 100 different types of germplasm.
Material received from Peru and Chile will be 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. Polymerase chain reaction of 57R will be conducted. This 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. By screening non-H1 material we may be able to find novel resistance genes to G. rostochiensis and G. ellingtonae. All of the material will be screened for resistance to the G. pallida population in Idaho.
Established techniques will be used to conduct screenings. Material from Chile and Peru 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 Desiree 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 an individual plants confer broad-spectrum resistance to multiple Globodera nematode species. The experimental units will be arranged in a complete randomized design with genotypes being replicated four to five times. Reproduction factor values (RF) were calculated as (final egg density/initial egg density) x 100. Potato ‘Désirée’ and ‘Russet Burbank’ were included in all trials as susceptible controls. 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 of Russet Burbank) x 100.
