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.

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).

This book is open access under a CC BY 4.0 license. This book provides a fresh, updated and science-based perspective on the current status and prospects of the diverse array of topics related to the potato, and was written by distinguished scientists with hands-on global experience in research aspects related to potato. The potato is the third most important global food crop in terms of consumption. Being the only vegetatively propagated species among the world’s main five staple crops creates both issues and opportunities for the potato: on the one hand, this constrains the speed of its geographic expansion and its options for international commercialization and distribution when compared with commodity crops such as maize, wheat or rice. On the other, it provides an effective insulation against speculation and unforeseen spikes in commodity prices, since the potato does not represent a good traded on global markets. These two factors highlight the underappreciated and underrated role of the potato as a dependable nutrition security crop, one that can mitigate turmoil in world food supply and demand and political instability in some developing countries. Increasingly, the global role of the potato has expanded from a profitable crop in developing countries to a crop providing income and nutrition security in developing ones. This book will appeal to academics and students of crop sciences, but also policy makers and other stakeholders involved in the potato and its contribution to humankind’s food security.

Potato (Solanum tuberosum L.) is a staple food in the world. Potato virus Y (PVY; Potyvirus: Potyviridae ) is an important virus that affects yield and quality of potatoes. PVY exists as biologically distinct strains: PVY-N induces systemic veinal necrosis in tobacco, PVY-O causes hypersensitive response (HR) in potato cultivars carrying the Ny gene and PVY-NTN produces necrotic rings on the tubers of sensitive potato cultivars. The vsiRNA profiles of three distinct PVY strains, ordinary (PVY-O), tobacco-veinal necrotic (PVY-N) and tuber-necrotic (PVY-NTN) strains were determined in potato cv. Russet Burbank. The frequency and distribution of vsiRNAs varied among different strains. PVY-NTN infected plants accumulated the highest population of PVY-vsiRNAs in comparison to plants infected with PVY-O and PVY-N. In PVY-infected plants, the 21 nt class was predominant whereas in healthy potato plants 24 nt class had the maximum population. VsiRNAs were derived from every nucleotide position of the PVY genome and certain hotspots were identified which produced relatively more vsiRNAs. Additionally, six novel microRNAs were found in PVY-infected plants. Potato virus S (PVS; Carlavirus: Betaflexiviridae) is another important potato virus distributed worldwide. The outcome of mixed infection of PVS and PVY was studied under controlled conditions in three potato cultivars, Defender, Desiree and Russet Burbank. Results showed that PVS has an antagonistic effect on PVY replication in mixed infection. The antagonistic effect was associated with less severe symptoms in dual infections as well as reduced PVY multiplication. Symptoms of PVS were not visible in Desiree and Russet Burbank plants except Defender which showed bronzing spots on the leaves. PVY symptoms included mosaic, mottling and leaf drop. It was found that the antagonistic effect of PVS on the replication of PVY is independent of host genetic background as the same pattern was found in all three potato cultivars. Potato cultivars such as Desiree carrying the Ny gene show HR to infection with the ordinary strain of PVY. In comparison to Russet Burbank, PVY levels in Desiree decreased with increasing number of days post-inoculation. The HR was found to be specific to PVY-O and was not elicited by infection by PVY-N or PVY-NTN.