Interactions among potato genotypes, virus strains, inoculation timing and method in the Potato virus Y and green peach aphid pathosystem

Interactions among potato genotypes, virus strains, inoculation timing and method in the Potato virus Y and green peach aphid pathosystem

Deepak Shrestha¹, Erik J. Wenninger², Pamela J. Hutchinson³, Shaonpius Mondal¹, Jonathan L. Whitworth⁴ , and Nilsa A. Bosque-Pérez¹

¹Department of Plant, Soil, and Entomological Sciences, University of Idaho, PO Box 442339, Moscow ID 83844; ²Kimberly R & E Center, University of Idaho, Kimberly, ID 83341; ³Aberdeen R & E Center, University of Idaho, Aberdeen, ID 83210; ⁴USDA-ARS. Aberdeen R &E Center, Aberdeen, ID, 83210 

 

Abstract                                                                           

Potato virus Y (PVY) is an economically important and remerging pathogen of potato in North America. PVY infection reduces yield and some necrotic and recombinant strains render the tuber unmarketable. Although the strain PVY^O is more prevalent in the United States, the necrotic and recombinant strains PVY^NTN and PVY^N:O are becoming widespread. Most varietal screening has been conducted via mechanical inoculation, however aphid inoculation is the most prevalent method of spread in the field. Additionally, genotype responses might differ between early and late season infection. The objectives of our studies were to determine if differences exist in the reactions of two potato genotypes (Yukon Gold, A98345-1) to: 1) three PVY strains, 2) two inoculation methods (aphid vs. mechanical), and 3) two growth stages at inoculation time (pre vs. post-flowering). Plant infection status was determined via DAS-ELISA. Infection percentages for each treatment were analyzed using the GENMOD procedure (binomial distribution, logit link transformation) in SAS. Results indicate Yukon Gold is more susceptible to PVY than A98345-1. The rank for total percentage infected plants from mechanical inoculation for Yukon Gold was PVY^O > PVY^N:O > PVY^NTN, and for A98345-1 it was PVY^N:O > PVY^O ≈ PVY^NTN. Total percentage infected plants from aphid inoculation for both genotypes ranked PVY^O ≈ PVY^N:O > PVY^NTN. In most instances, percentage infected plants was higher following mechanical inoculation compared to aphid inoculation. Percentage of infection for pre-flowering was higher than post-flowering indicating both genotypes exhibit age-based resistance to PVY. Implications of these findings will be discussed.