Submitted to: Potato Progress
Publication Type: Popular Publication
Publication Acceptance Date: September 1, 2005
Publication Date: September 21, 2005
Citation: Crosslin, J. 2005. PVY: What, Where, and Why. Potato Progress. Vol. V(14):2-4. Technical Abstract: Potato virus Y (PVY) is found worldwide wherever potatoes are grown. PVY was first described in the 1930’s. Since that time different strains, or biological types, of virus have been described. The so-called ordinary strain (PVYO) has been found in potatoes around the world. This strain causes a mottling or mosaic discoloration of the foliage in infected potatoes. In tobacco, PVYO causes a distinct systemic mottle. The tobacco necrotic strain (PVYN) causes a reaction in tobacco in which the veins and eventually the rest of the leaf become brown and die. In most cultivars of potatoes PVYN produces relatively mild mottling. PVYN is widespread in Europe. It was first found in North America about 1990 in eastern Canada. A subgroup of the PVYN strain, called the tuber necrotic strain (PVYNTN), was originally described in Europe in the 1970’s. This strain causes internal and external rings and discolorations in tubers. Recently the PVYN and PVYNTN strains have been identified in potato-growing regions of the western United States and Canada. In the 1990’s in Europe strains of PVY were found that caused necrosis in tobacco, as does PVYN, but had characteristics of PVYO also. At about this time specific monoclonal antibodies (Mabs) became available. These Mabs were capable of differentiating PVYO from PVYN, yet they identified these new necrotic-type of viruses as PVYO. By the end of the 1990’s this recombinant strain was the predominant type of PVY found in many potato-producing areas of Europe. In 2001-2002 researchers in Washington, Oregon, and Idaho observed symptoms on potatoes that suggested an unusual strain of PVY might be present. Transmission of these viruses to tobacco resulted in systemic necrosis confirming for the first time that PVYN strains were present in major potato-growing regions of the western United States. Further tests have indicated that in the western U.S. we have PVYO, PVYN, PVYNTN, and recombinants. Some of the recombinant viruses from Canada and the U.S. have been designated PVYN:O to indicate that they possess characteristics of both PVYO and PVYN. The difficulties associated with the detection and identification of PVYN, PVYNTN, and PVYN:O are discussed.