Location: National Germplasm Resources Laboratory
Project Number: 8042-22000-324-003-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2025
End Date: Dec 31, 2026
Objective:
Objective 1: Evaluate the diversity of TRV in the San Luis Valley and identify the TRV infection type, i.e. multiplying or non-multiplying infections. Collect field samples from grower fields and test for TRV. Sequence samples using high throughput sequencing (HTS) for a comprehensive overview of the TRV genetic composition.
Objective 2: Evaluate the impact of early infections on the transmission to progeny tubers which may affect the effectiveness of the timing of Vydate applications. Greenhouse trials will be conducted by applying a nematicide to control the TRV vector over the growing season.
Objective 3: Identify the alternative hosts of TRV in rotation crops and green manure crops. Several hosts and crops will be sampled in neighboring fields and in rotation fields. Samples will be tested using a validated RT-qPCR protocol.
Approach:
1. Potato tuber samples of multiple cultivars will be collected from the San Luis Valley, Colorado, and visually assessed for external and internal necrosis and further selected for additional characterization. At least 120 tubers with CRS symptoms will be tested for TRV using RT-qPCR. A total of at least half the TRV positive samples will be sub-sampled for library preparation and high throughput sequencing (HTS) to characterize TRV strains compared to those available in literature and international DNA database and determine their infection types by examining for the presence or absence of virus segments in the tubers.
This objective has both a field and laboratory component that will be jointly addressed by both cooperators. Sample collection, preliminary screening of tubers, and testing will be carried out by the Cooperator. Sample processing will be jointly addressed by both cooperators. Molecular testing will be conducted at the ARS PI laboratory.
This objective will be achieved by joint efforts of ARS and the Cooperator.
2. To estimate the timing of early TRV infection by nematode, we will test potato plants during the early growing stages and before tuber initiation. Up to 5 fields with TRV infection history will be identified and sprouted mother tubers will be collected from affected field spots, usually with coiled sprouts and delayed emergence. Parts of these small potato plants will be tested for TRV, including roots, sprouts and mother tubers. Then, TRV positive plants will be grown in the greenhouse in nematode-free soil, and progeny tubers will be tested for TRV to evaluate the infection rates early in the growing season. This information will help potato growers determine the timing for the first chemigation, such as Vydate, and the importance of early nematode feeding on the incidence of TRV and symptoms of CRS.
This objective has a field component that will be carried out by the Cooperator.
3. To develop an effective management program of CRS, we will identify rotation crops and green manure that act as alternative hosts to TRV and identify poor or nonhost plants/crops to control this virus and eradicate it from soil nematode population of a given field. Samples from crops and weeds will be collected from fields in the San Luis Valley at different stages of a single growing season and will be tested for TRV. RT-qPCR will be used to test root, stem and leaf parts of these weeds and crops.
This objective has a field component that will be carried out by the Cooperator.
We plan to communicate the results of this project through field days (SLVRC Field Day), conferences (e.g. the Southern Rocky Mountain Agricultural Conference, Washington and Oregon Annual Potato Conference, and Idaho Potato Conference), WERA89 annual meeting, SLVRC Potato Pathology newsletters, social media platforms, the PAA Annual Meeting, Potato Grower and Spudman Magazines. This has an outreach component that will be carried out by both ARS and the Cooperator.