Potato Cultivar and Seed Type Affect the Development of Systemic Potato virus Y (PVYN-Wi) Infection

Abstract

Potato virus Y (PVY) infection is one of the greatest challenges to seed potato production in the United States. To determine how cultivar and seed type affect the development of systemic PVY infection, Russet Burbank and Russet Norkotah Colorado 3 cultivars were grown from two types of pre-nuclear seed (i.e., plantlets and minitubers) and Generation 3 (G3) tubers and challenged with PVY strain Wilga (PVY N-Wi ). Systemic PVY infection was measured by assaying spread of virus from the inoculation site to upper non-inoculated leaves. The Burbank cultivar had a lower incidence of systemic PVY infection compared to the incidence of systemic PVY that developed in the Colorado 3 cultivar. Furthermore, Burbank plants grown from G3 tubers had a lower incidence of systemic PVY infection, as compared to Burbank plants grown from plantlets. Together our results indicate that both cultivar and seed type affect the development of systemic PVY N-Wi infections post-inoculation. ResumenLa infección por virus Y (PVY) es uno de los mayores retos en la producción de semilla de papa en los Estados Unidos. Para determinar cómo afecta la variedad y el tipo de semilla al desarrollo de la infección sistémica de PVY, se cultivaron las variedades Russet Burbank y Russet Norkotah Colorado 3 de dos tipos de semilla pre-nuclear (p. e., plántulas y minitubérculos) y de tubérculos de la Generación 3 (G3), y se inocularon con PVY variante Wilga (PVYN-Wi). La infección sistémica de PVY se midió mediante la detección de la dispersión del virus desde el sitio de inoculación hacia las hojas superiores no inoculadas. La variedad Burbank tuvo la incidencia más baja de infección sistémica de PVYen comparación con la incidencia de PVY sistémico que se desarrolló en la variedad Colorado 3. Aún más, las plantas de Burbank originadas de los tubérculos de G3 tuvieron la incidencia más baja de infección sistémica de PVY, en comparación con las plantas de Burbank originadas de plántulas. Juntos, nuestros resultados indican que tanto la variedad como el tipo de semilla afectan el desarrollo de infecciones sistémicas de PVYN-Wi después de la inoculación.

Transcriptome and Small RNA Profiling of Potato Virus Y Infected Potato Cultivars, Including Systemically Infected Russet Burbank

“…Thus, the transcriptional response to PVY was further assessed over a time course of infection, including the previously discussed 24 hpi time point and additional time points (i.e., 1 and 4 wpi). Systemic infection of PVY takes approximately four weeks to develop in Russet Burbank plants [ 40 ]. For these additional time points, PVY samples were obtained from leaves distal to the inoculation site since the effects of PVY infection on distal yet uninfected regions of potato plants is not well understood, as many previous sequencing efforts have focused on the early responses (i.e., 6 hpi to 5 days post-inoculation) of inoculated leaves [ 12 , 64 ].…”

“…That we found similar results in a tolerant infection with a different potato cultivar (i.e., Russet Burbank) and different PVY strain (i.e., PVY N-Wi ), further strengthens previous findings [ 74 ]. Symptoms of PVY infection can vary with environmental conditions and while we observed tolerant-like infections in Russet Burbank plants grown from sterile tissue culture in growth chambers, symptomatic infections can develop in field conditions [ 40 ].…”

“…The PVY strain Wilga (PVY N-Wi ) (NCBI Accession: HQ912863) was obtained from the Karasev Lab at the University of Idaho. PVY N-Wi stock was maintained in tobacco plants ( Nicotiana tabacum ‘Samsun’), which were cultivated from seed with a 24-hour (h) photoperiod at 22 °C in 10″ pots, as previously described [ 40 ]. The genome sequence of PVY N-Wi utilized in this study was verified by RNASeq and shares 99.7% nucleotide identity with the PVY N-Wi reference genome (HQ912863).…”

“…Leaf tissue was stored in a −80 °C freezer until analysis. For each of three biological replicates of the experiment, six plants were mechanically inoculated with PVY N-Wi (NCBI Accession: HQ912863) or inoculation buffer (i.e., mock-infected) [ 40 ]. RNA sequencing performed on three of the six plants per treatment group in biological replicate #1 (i.e., n = 3 RNA samples per treatment group per time point), and qPCR was performed on all the plant samples in this study (i.e., n = 6 plants per treatment group, sampled at three time points post-inoculation) for each biological replicate of the experiment and all three biological replicates performed as part of this study (Figure 1, Supplementary File S1A ).…”

“…Previous studies examined the transcriptional responses of Russet Burbank plants infected with two PVY strains (i.e., PVY O , PVY NTN ) 4- and 10-hours post-infection (hpi) in inoculated leaves, and other studies characterized large transcriptional changes in PVY-infected plants 1- and 3-days post-infection [ 12 , 13 ]. In our previous studies, we determined that systemic PVY N-Wi infection of Russet Burbank takes a few weeks to develop [ 40 ], therefore, in this study we evaluated the transcriptional and small RNA responses early in infection (i.e., 24 hpi in inoculated leaves), as well as later time points (i.e., 1 and 4 weeks post-infection (wpi)) in upper uninoculated leaves to identify the changes during development of systemic PVY-infection.…”