BIOLOGICAL AND MOLECULAR PROPERTIES OF POTATO VIRUS S (PVS) AND THE EFFECT OF PVS ON LATE BLIGHT RESISTANT POTATO GENOTYPES

Thesis (Ph.D.), Department of Plant Pathology, Washington State UniversityPotato (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. Under field conditions, however, this cultivar exhibits high susceptibility to infection by Potato virus S (PVS, family Betaflexiviridae, genus Carlavirus ). My research reproduced this phenotype under controlled conditions and demonstrated the tuber/seed transmission and proved modified Koch's postulates.Department of Plant Pathology, Washington State Universit