Location: Temperate Tree Fruit and Vegetable Research
Project Number: 2092-21220-003-004-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Apr 1, 2019
End Date: Jun 30, 2023
Objective:
We will address the potato susceptibility to Beet Curly Top Virus (BCTV) from two separate directions: the insect and the potato plant. In our first objective, we will assess natural BCTV strain diversity in the Pacific Northwest by subjecting leafhoppers collected from different weed and crop hosts in a Washington State monitoring program for BLTVA analysis to additional testing for BCTV. In our second objective, we will study the complete pathogenicity cycle in the susceptible potato cultivar, Yukon Gold, by assessing primary infection of different BCTV strains, observing foliar and tuber symptom development, and then planting the infected tubers to study the secondary infection in foliage and in tubers. In our third objective, we propose to screen additional potato cultivars for their susceptibility (or resistance) to BCTV strains circulating in the field in order to reveal potential vulnerabilities in potato cultivars grown in the PNW.
Approach:
1. Beet Curly Top Virus (BCTV) testing of beet leafhoppers collected in the beet leafhopper-transmitted virescence agent (BLTVA) monitoring program. We will use our differentiating primers developed to quickly identify BCTV strains for PCR analysis on the total nucleic acids extracted from the insects. We will also test suspicious potato leaf samples submitted by stakeholders in Idaho, Washington, and Oregon, for cases of an unexplained biotic-looking damage.
2. Understanding the pathogenicity cycle of BCTV in the potato cultivar, Yukon Gold. The potato cultivar known to be susceptible to BCTV (Yukon Gold) will be grown from virus-free plantlets received from the Potato Tissue Culture collection in Moscow, Idaho, and inoculated, 3-5 plants per cultivar per strain, with infectious clones of BCTV. The agroinoculation will be performed with a syringe injecting bacterial suspension carrying the desired construct into the stem close to the growing point of a young plant. Systemic infection will be monitored between 2 to 8 weeks post-inoculation through visual observations, ELISA and PCR tests to confirm the infection. Control agroinoculations of the BCTV strains into a susceptible host, Nicotiana benthamiana, will be used in each experiment. All infected plants will be maintained until vine-kill and tubers harvested and scored for the external and internal defects, focusing on the possible tuber damage. Harvested tubers will be stored at room temperature in the dark, until sprouting, and will be planted in 1-gallon pots in the greenhouse. The secondary infection will be followed and monitored similar to the primary infection, until the final tuber harvest and evaluation at the end of the experiment.
3. Screening potato cultivars for susceptibility to BCTV. Virus-free plantlets of Russet Burbank, Clearwater Russet, and Russet Norkotah selection will be received from the Potato Tissue Culture collection in Moscow, Idaho, and inoculated, 3-5 plants per cultivar per strain, with infectious clones of BCTV. Systemic infection will be monitored between 2 to 8 weeks post-inoculation through visual observations, ELISA, and PCR tests to confirm the infection. Control agroinoculations of the BCTV strains into a susceptible host, Nicotiana benthamiana, will be used in each experiment.
