Potato Virus Research at Moscow campus

Part of a continuing UI Potato Research Series

Published in the February 2012 Issue Published online: Feb 06, 2012 University of Idaho Potato Team
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University of Idaho Plant Virologist Dr. Alexander Karasev and his team of three technical support staff, two postdoctoral scientists, five graduate and two undergraduate students operate several potato research projects from the main campus of the University of Idaho in Moscow. These include basic research projects on Potato virus Y (PVY) and Potato leafroll virus (PLRV), detection and typing of PVY strains in Idaho potato seed lots, development of new diagnostic tools to detect and differentiate potato viruses and a small-scale virus diagnostic service run for Idaho clientele.


R & E Activities Funded IPC

Detection and typing of PVY strains in Idaho potato seed lots. Research on potato viruses affecting tuber yield and quality is the most important work performed by Karasev's group. Invasion and spread of new, recombinant PVY strains that induce potato tuber necrotic ringspot disease (PTNRD) made this virus one of the main subjects of the plant virus research program on campus.

PTNRD makes tubers of susceptible cultivars unmarketable for the fresh potato market. These tuber necrotic strains of PVY are more difficult to manage through the seed potato certification program, because they produce very mild or no foliar symptoms in potato cultivars common in the U.S.

Necrotic PVY strains can be identified by complex laboratory detection methods, like ELISA or RT-PCR, which can detect minute changes in virus properties associated with their ability to cause disease. Once identified in affected tuber lots, these necrotic PVY strains can be confined and removed from the seed potato production system. In collaboration with the seed potato research laboratory in Idaho Falls (PI - Dr. Phil Nolte), the plant virology laboratory of Dr. Karasev is studying incidence and distribution of tuber necrotic strains of PVY in Idaho seed potato lots, aiming at finding hidden sources of the recombinant strains, confining their spread and eradicating necrotic strains of PVY from Idaho potato. This research directly complements the efforts of Idaho Potato Seed Certification to reduce the number of rejected seed lots and increase the overall quality and competitiveness of the Idaho seed potato production.

Production of virus-free potato lines and search for PVY resistance in potato. Another grant from the Idaho Potato Commission funds the joint research project between the Plant Virology Laboratory and Lori Ewing, Director of the Potato Tissue Culture Laboratory in Moscow. This funding is aimed at maintaining the virus-free status for over 200 potato lines housed in this University of Idaho facility.

These potato lines are maintained under pathogen-free conditions in sterile tubes, and serve as true-to-type standards for potato production not only in Idaho, but also in Oregon and Washington. The result is that this program is ultimately responsible for 55 percent of the U.S. potato crop. Karasev's group makes sure these potato lines are virus-free.

One additional objective of this IPC-funded project is to screen Idaho-grown cultivars for resistance to different strains of PVY. Breeding for PVY resistance was not considered a priority until recently, and the potato industry relied on seed certification to manage the PVY problem. With the spread of tuber necrotic strains of PVY, causing mild or no foliar symptoms, search for sources of resistance to PVY is now on. The Plant Virology Laboratory screens potato cultivars displaying hypersensitive resistance to PVY, which is strain specific. The result? A new source of resistance to PVYN was recently found.

Other Research Activities. Karasev's group has also studied new types of PVY recombinants and serological variants, some of which are not yet known in the U.S. or in North America. This research has been funded by the U.S. Potato Board. Through collaborations with other potato virologists in Mexico and Brazil, new types of PVY strains have been identified and specific methods for their detection have been developed.

These methods have been employed by quarantine agencies to prevent introduction of new, alien strains into the U.S. Research conducted in the Plant Virology Laboratory also helped to remove trade barriers for export of fresh potato to Mexico.

Funding from the competitive programs at the USDA-NIFA-AFRI is being used to study genetic diversity of PVY in the United States, and to elucidate mechanisms of aphid transmission of PLRV, another aphid-transmitted potato virus. Both projects are focused on understanding basic processes driving diversity, evolution and genetic factors responsible for disease induction and vector transmission in potato viruses.

Potato Virus Diagnostic Laboratory. The Plant Virology Laboratory maintains a large collection of virus-specific antibodies specific to major potato viruses. Antibodies were produced with the help of an IPC-funded grant. These antibodies are provided to Idaho laboratories engaged in virus testing, to potato seed certification agencies in other states and other countries, and to private diagnostic companies from the U.S., Canada and Europe.

The lab is also involved in potato virus detection and PVY typing using RT-PCR and specific primers, conducting tests for all potato viruses, and for the zebra chip agent by PCR. Occasional small-scale tests are conducted for clientele in Idaho. The lab is equipped with ELISA reader, several PCR machines, electrophoretic equipment, microscopes, autoclave (sterilizer) as well as a laminar flow hood (used to work with disease organisms in a sterile environment), and all of the equipment necessary to diagnose potato viruses by ELISA or RT-PCR. Contact Alex Karasev if you need to test leaf or tuber samples.

The Plant Virology Laboratory has the goal of improving seed potato quality, reducing risks to all aspects of the industry and keeping the industry informed of current and future threats. Input from the Idaho potato industry is always welcome. If you have questions or comments, feel free to contact Dr. Karasev at (208) 885-2350 or email him at akarasev@uidaho.edu.