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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Research Project #443209

Research Project: Potato Cyst Nematode (Globodera spp.) Genetic Diversity

Location: Horticultural Crops Disease and Pest Management Research Unit

Project Number: 2072-22000-046-027-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2022
End Date: Aug 31, 2024

Characterize the genetic diversity of Globodera spp. from Central and South America.

We will work closely with in-country entities to sample Globodera populations and select resistant germplasm for screening against the populations. By working with several different countries that encompass the evolutionary center of Globodera and of potato, we anticipate finding new pathotypes of Globodera spp., while increasing the likelihood of identifying material with resistance to Globodera spp. We have networks in place with scientists from Servicio Agricola y Ganadero (SAG) in Chile, and colleagues in Peru, Bolivia, and Guatemala to aid in the sampling and collection of Globodera populations from potato fields. Globodera populations from Peru, Chile, and Bolivia has been shipped to the U.S. under an USDA-APHIS permit which allows for screening with differential lines to determine pathotype. In addition to Globodera populations, researchers have successfully identified disease resistance in germplasm that has evolved in the presence of the pathogen. Solanum germplasm from Peru, Chile, and Bolivia has been exposed to Globodera and may have unique resistances. Our goal is to test some of this germplasm in country (Bolivia) to determine if any are resistant to the Globodera species. A selection of PCN populations shown to represent a diversity of pathotypes will be selected for screening against a set of potato differentials. These assays will be conducted in a closed, container assay system at the University of Idaho. A small, clear plastic container will be filled with pasteurized soil and a tuber piece placed in the soil after which cysts of PCN will be added. The system will by hydrated with water and then sealed and placed in a growth chamber at 20 ºC. The life cycle of PCN takes about 3 months at this temperature. At the end of this time, cysts can be counted on roots growing near the surface of the plastic container. This contained system allows for the evaluation of PCN reproduction on potato without the need for end extraction reducing potential contamination. Populations received from South America will be genetically characterized using two methods. 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 additional SNP that exist between populations.