Potato virus Y (PVY) infects a wide host range mainly within the Solanaceae and is distributed worldwide. PVY is transmitted by more than 40 aphid species in a non persistent manner. Isolates of the PVY species are highly variable at biological, serological and molecular levels. Epidemiological studies have highlighted the emergence of distinct potato PVY variants able to induce necroses on potato tubers. Due to the lack of efficient resistance to PVY isolates inducing necrotic symptoms in cultivated varieties and the plant-to-plant transmission of isolates through the daughter tubers, PVY has become the most economically important virus for the potato industry. The review offers an overview of several decades of research on PVY but also focuses on the latest data obtained by expert on PVY worldwide on the biological characteristics of PVY, interactions between aphids-hosts, its evolution and management. Identified knowledge gaps to understand further PVY biology will be discussed.

Viral phytopathogens attack a wide range of crops worldwide, resulting in economic losses of nearly US$60 billion annually. In potato (Solanum tuberosum L.), the most devastating crop losses are caused by potato virus Y (PVY). Until recently, resistant cultivars have been used as the most cost-effective and reliable option for managing PVY in potato. However, the current arsenal of genetic resistance appears inadequate for combating the recent emergence of more aggressive strains such as PVYNTN and PVYN-Wi.Developing effective genetic resistance to these strains would greatly benefit from an in-depth picture of the strategies they use that result in host susceptibility. Thus, the goal of this dissertation was to gain a system-wide view of the changes occurring in potato after infection with these necrotic strains. For this, gas chromatography coupled with mass spectroscopy (GC0́3MS) was first used for an untargeted investigation of the changes in leaf metabolomes of PVY-resistant cultivar Premier Russet, and a susceptible cultivar, Russet Burbank, following inoculation with PVYNTN, PVYN-Wi, and their common progenitor PVYO. Subsequently, the transcriptional responses of these inoculated plants were then examined using mRNA-seq.At the metabolome level, the analysis showed PVY infections in potato elicit detectable changes in several primary metabolic pathways related to amino acid, energy, and fatty acid metabolism. In the resistant cv. Premier Russet, a major overlap in differential accumulation was found between PVYN-Wi and PVYO. In contrast, the main overlap in differential metabolite profiles and pathways in the susceptible cv. Russet Burbank was between PVYNTN and PVYO. Overall, limited overlap was observed between PVYNTN and PVYN-Wi, suggesting that PVYN-Wi-induced necrosis may be mechanistically distinguishable from that of PVYNTN.At the transcriptome level, primary metabolism was also shown to be affected by all three PVY inoculations. In addition, the analysis also recovered a core set of 9 pathways of secondary metabolism that may confer the PVY susceptibility in Russet Burbank. These pathways can potentially be targeted for developing genetic resistance in potato and other economically important Solanaceous PVY hosts.

Potato (Solanum tuberosum) is one of the most important crops grown in Washington State. In 2011, Washington growers raised 160,000 acres of potatoes with an average yield of 615 CWT per acre, 98 CWT total, with a farm gate value of over $734 million. Late blight, caused by Phytophthora infestans, is an extremely devastating disease of potato worldwide. Defender is the only cultivar with foliar and tuber resistance to this disease in the U.S. However, under field conditions this cultivar exhibits high susceptibility to infection by Potato virus S (PVS, family Betaflexiviridae, genus Carlavirus).