Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/1999
Publication Date: N/A
Interpretive Summary: Barley yellow dwarf viruses (BYDVs) cause the most damaging virus disease of cereal crops. These viruses are transmitted from infected to healthy plants through the feeding of aphids. The dependence of the BYDVs on aphids for their spread makes them vulnerable to control by treatments that interfere with aphid feeding and/or migration. However, little is known about the specifics of how aphids move viruses within or among different host plants. This is partially due to the fact that aphids carrying BYDVs are very common in the small grain growing regions of the US, which makes tracking the spread of a single BYDV infection nearly impossible. To overcome this problem, we have identified a relatively rare isolate of BYDV that can be identified by molecular technologies. This rare virus can be differentiated from the more common isolates by a laboratory assay. The use of this traceable BYDV isolate will allow us to establish infections at known locations and monitor the spread of the virus from that site over time. This information will be useful to scientists who are interested in developing virus control strategies by studying the dynamics of the spread of BYDVs in areas of high natural infection.
Technical Abstract: In consecutive annual statewide surveys of the incidence of barley yellow dwarf viruses (BYDVs) in Illinois wheat and oat fields, 27 BYDV-PAV-like isolates were identified. Using polymerase chain reaction (PCR), the coat protein regions of all 27 isolates were analyzed for restriction-fragment-length polymorphisms. The PCR products of two isolates, one from each year, had restriction fragment profiles after digestion with HaeIII that differed from the other isolates. The nucleotide sequences of the coat protein regions of a laboratory isolate, BYDV-PAV-IL (PAV-IL), two of the isolates with the common restriction profile, and the two isolates with polymorphic profiles were greater than 98% identical. The relatively rare isolate identified during the first year was designated BYDV-PAV-DK1 (PAV-DK1) and further characterized biologically. PAV-DK1 was compared to PAV-IL in terms of symptom severity and efficiency of aphid transmission. PAV-DK1 and PAV-IL did not differ significantly in symptom expression, but did differ significantly in rates of transmission by two out of the three biotypes of Rhopalosiphum padi (L.) examined. Since PAV-DK1 does not occur in high levels in the state of Illinois, and its PCR products have a unique restriction enzyme profile, it has the potential to be used as a traceable isolate in field epidemiological experiments.