Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2014
Publication Date: 6/1/2014
Citation: Shrestha, D., Wenninger, E.J., Hutchinson, P.J., Whitworth, J.L., Mondal, S., Eigenbrode, S.D., Bosque-Perez, N.A. 2014. Interactions among potato genotypes, virus strains, and inoculation timing and methods in the Potato virus Y and green peach aphid pathosystem. Environmental Entomology. 43:662-671. Interpretive Summary: The increase in Potato virus Y (PVY) in recent years in North America has seen an increase in different strains of PVY. PVYO is most prevalent, but necrotic recombinant strains of PVYN:O and PVYNTN are becoming widespread. In addition, potato varieties differ in their susceptibility to the PVY strains. ELISA testing, a serological based test was used to characterize infection reactions of susceptible Yukon Gold plants and semi-resistant A98345-1 plants. These plants were infected mechanically (by hand) by wounding plant leaves and applying virus infected plant sap and by green peach aphids which carried the virus. Plants were also inoculated at the pre- and post-flowering stages. Results showed that Yukon Gold was more susceptible to PVYO, while A98345-1 was most susceptible to PVYN:O. The ranking of virus concentration, or titer, from high to low in the infected plants was PVYO, PVYNTN, PVYN:O and it was also noted that younger plants (pre-flowering) were more susceptible than post-flowering plants. Plants were more susceptible when mechanically infected than when infected by virus-carrying aphids. These results show the differences between genotype (variety), virus strain, plant growth stage at inoculation, and infection mechanically or by aphids. This information should be taken into account when planning virus characterization experiments.
Technical Abstract: Potato virus Y (PVY) is an economically important and reemerging potato pathogen in North America. PVY infection reduces yield, and some necrotic and recombinant strains render tubers unmarketable. Although PVYO is the most prevalent strain in the United States, the necrotic and recombinant strains PVYNTN and PVYN:O are becoming more widespread. Infection rates in aphid-inoculated [Myzus persicae (Sulzer)] and mechanically inoculated plants were compared across two potato genotypes (‘Yukon Gold’ and A98345-1), three PVY strains (PVYO, PVYN:O, and PVYNTN), and two growth stages at inoculation (pre- and post-flowering). Susceptibility of genotypes was measured as infection rate using DAS-ELISA; virus titer and tuber mass also were recorded from the infected plants. Yukon Gold generally was more susceptible than A98345-1 to all three PVY strains, especially following mechanical inoculation. Within genotypes, Yukon Gold was most susceptible to PVYO and A98345-1 was most susceptible to PVYN:O. Plants exhibited age-based resistance, with both genotypes showing higher susceptibility at the pre- than post-flowering stage. The overall ranking from high to low of virus titer in infected plants was PVYO, PVYNTN, PVYN:O; across all three strains, infected Yukon Gold had higher titer than infected A98345-1 plants. Yukon Gold plants had lower tuber mass than A98345-1 when infected, and there were differences between the two inoculation methods in regard to tuber mass for the three stains. The results showed differences in infection response between inoculation methods and as a function of genotype, strain, inoculation stage, and their interactions. These factors should be considered when screening genotypes for resistance.