BackgroundPotato virus Y (PVY) is one of the most important plant viruses affecting potato production. The interactions between potato and PVY are complex and the outcome of the interactions depends on the potato genotype, the PVY strain, and the environmental conditions. A potato cultivar can induce resistance to a specific PVY strain, yet be susceptible to another. How a single potato cultivar responds to PVY in both compatible and incompatible interactions is not clear.ResultsIn this study, we used RNA-sequencing (RNA-Seq) to investigate and compare the transcriptional changes in leaves of potato upon inoculation with PVY. We used two potato varieties: Premier Russet, which is resistant to the PVY strain O (PVYO) but susceptible to the strain NTN (PVYNTN), and Russet Burbank, which is susceptible to all PVY strains that have been tested. Leaves were inoculated with PVYO or PVYNTN, and samples were collected 4 and 10 h post inoculation (hpi). A larger number of differentially expressed (DE) genes were found in the compatible reactions compared to the incompatible reaction. For all treatments, the majority of DE genes were down-regulated at 4 hpi and up-regulated at 10 hpi. Gene Ontology enrichment analysis showed enrichment of the biological process GO term “Photosynthesis, light harvesting” specifically in PVYO-inoculated Premier Russet leaves, while the GO term “nucleosome assembly” was largely overrepresented in PVYNTN-inoculated Premier Russet leaves and PVYO-inoculated Russet Burbank leaves but not in PVYO-inoculated Premier Russet leaves. Fewer genes were DE over 4-fold in the incompatible reaction compared to the compatible reactions. Amongst these, five genes were DE only in PVYO-inoculated Premier Russet leaves, and all five were down-regulated. These genes are predicted to encode for a putative ABC transporter, a MYC2 transcription factor, a VQ-motif containing protein, a non-specific lipid-transfer protein, and a xyloglucan endotransglucosylase-hydroxylase.ConclusionsOur results show that the incompatible and compatible reactions in Premier Russet shared more similarities, in particular during the initial response, than the compatible reactions in the two different hosts. Our results identify potential key processes and genes that determine the fate of the reaction, compatible or incompatible, between PVY and its host.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1666-2) contains supplementary material, which is available to authorized users.

Standardized RT-PCR procedures were devel-

Root galls possibly caused by Spongospora subterranea were observed on hairy nightshade (Solanum sarrachoide; HNS). HNS galls and galls from potato were used to artificially inoculate potato and HNS. Eighty-three and 52% potato and HNS plants inoculated with potato inoculum had root galls, respectively. Ten and 31% potato and HNS plants inoculated with HNS inoculum had root galls, respectively. A S. subterranea-specific PCR significantly correlated (P<0.0001, Phi Coefficient=0.69) with visual assessment of gall incidence in 34 of 40 samples. Five of 40 samples had no galls, but gave positive PCRs. One of 40 samples had root galls, but gave a negative PCR. More sporosori were produced on potato than on HNS. Therefore, the root galls on HNS were caused by S. subterranea that is able to complete its life cycle on HNS and produce new generations of sporosori that are infectious on potato.Resumen Agallas de la raíz, posiblemente causadas por Spongospora subterranea fueron observadas en belladona vellosa (Solanum sarrachoide; HNS). Agallas de HNS y de papa fueron utilizadas para inocular artificialmente papa y HNS. El 83% y el 52% de plantas de papa y HNS inoculadas con inóculo de papa tuvieron agallas de la raíz respectivamente. El 10% y 31% de plantas de papa y HNS inoculadas con inóculo de HNS tuvieron agallas de la raíz respectivamente. Un PCR especifico para S. subterranea correlacionó significativamente (P<0.0001, Coeficiente Phi=0.69) con evaluación visual de incidencia de agallas en 34 de 40 muestras. Cinco de 40 muestras no tuvieron agallas pero dieron PCR positivo. Una de las 40 muestras tuvo agallas de la raíz pero dio PCR negativo. Más sporosori fue producido en papa que en HNS. Por lo tanto las agallas de la raíz en HNS fueron causadas por S. subterranea que es capaz de completar su ciclo de vida en HNS y producir nuevas generaciones de sporosori que son infecciosas en papa.

Tobacco rattle virus (TRV) causes the economically important corky ring spot disease in potato. Chemical control is difficult due to the soilborne nature of the TRV-transmitting nematode vector, and identifying natural host resistance against TRV is considered to be the optimal control measure. The present study investigated the sensitivity of 63 cultivars representing all market types (evaluated at North Dakota and Washington over 2 years) for the incidence of TRV-induced tuber necrosis and severity. This article also investigates the cultivar–location interaction (using a mixed-effects model) for TRV-induced necrosis. TRV-induced tuber necrosis (P < 0.0001) and severity (P < 0.0001) were significantly different among cultivars evaluated separately in North Dakota and Washington trials. Mixed-effects model results of pooled data (North Dakota and Washington) demonstrated that the interaction of cultivar and location had a significant effect (P = 0.03) on TRV-induced necrosis. Based on the virus-induced tuber necrosis data from both years and locations, cultivars were categorized into sensitive, moderately sensitive, insensitive, and moderately insensitive groups. Based on data from North Dakota, 10 cultivars, including Bintje, Centennial Russet, Ciklamen, Gala, Lelah, Oneida Gold, POR06V12-3, Rio Colorado, Russian Banana, and Superior, were rated as insensitive to TRV-induced tuber necrosis. Similar trials assessing TRV sensitivity among cultivars conducted in Washington resulted in a number of differences in sensitivity rankings compared with North Dakota trials. A substantial shift in sensitivity of some potato cultivars to TRV-induced tuber necrosis was observed between the two locations. Four cultivars (Centennial Russet, Oneida Gold, Russian Banana, and Superior) ranked as insensitive for North Dakota trials were ranked as sensitive for Washington trials. These results can assist the potato industry in making cultivar choices to reduce the economic impact of TRV-induced tuber necrosis.