Two Spud Scourges Return with a Vengeance

Two decades ago, the golden nematode and potato virus Y (PVY), two especially persistent scourges of potato were brought under control. But a new race of nematode and the widespread acceptance and planting of potato varieties which turned out to be asymptomatic carriers of PVY jeopardized it all. PVY’s resurgence impedes efforts to identify virus-infected seed potatoes and limit their distribution. These developments have been disheartening to people fighting to save the spud.

Agricultural Research Service (ARS) and Cornell University researchers have introduced more than 30 potato varieties that resist the original nematode race. The resistance is due to a potato gene called H1. But H1 has no effect on the new nematode race, first identified in 1995, which scientists have dubbed “Ro2.” At present, there is no rapid identification scheme for the two races. Scientists are hoping Ro2’s eggs and genes can be used as part of a race-identification strategy. An emerging molecular method called “RNA interference” that uses fragments of double-stranded RNA to hinder, or silence, gene expression may someday help develop an improved spud variety. PVY threatens not only potato, but also other crops such as tomato, pepper, and tobacco. The once-distinct PVY strain groupings are becoming inapplicable because of genetic recombination and mutation in the virus. To control the spread of PVY, ARS plant pathologist Stewart Gray has helped develop and implement the Canada/U.S. Management Plan for Potato Viruses That Cause Tuber Necrosis. PVY management strategies will be improved, and regional approaches to the PVY problem may be more appropriate, according to Gray.   

To read more: http://www.ars.usda.gov/is/AR/archive/aug07/potatoes0807.htm .