b'virus (AMV), tobacco rattle virus (TRV) and potato mop-top virus (PMTV). NECROTIC VIRUS PROJECT BREAKDOWNAMV has a wide host range and can infect more than 150 species of 22 plant families, with potato being one. It was Provinces where trials are being done:previously called potato calico virus as it causes bright yellowo Manitobablotching or mottling on leaves. AMV infections are usuallyo New Brunswickminor in potato crops, not impacting potato production costs Research teamsignificantly. Nie first heard of it in 2015 when AMV waso New Brunswickidentified as causing severe internal necrosis in tuber samples- Xianzhou Nie, AAFC Frederictonfrom New Brunswick. -Mathuresh Singh, Agricultural Certification PMTV is a soilborne virus that can cause severe tuber diseaseServices Inc. called spraingindicated by internal necrotic arcs or rings- Gary Hawkins, McCain Foodsin infected potato tubers. Diseased tubers lose market value,- Laixing Wang, McCain Foodscausing significant economic losses when disease incidence- JacquesLavoie, New Brunswick Department is high. It was first reported in North America in 2003, withof Agriculture, Aquaculture and Fisheries numerous reports in the U.S. and Canada having happenedo Prince Edward Islandsince then. Due to the soilborne nature of PMTV, controlling it is- Sean Liu, Canadian Food Inspection Agencychallenging.- Huimin Xu, Canadian Food Inspection AgencyPMTV survives in the soils for many, many years on viruso Manitobainfected scab fungus. PMTV can infect any of the solanaceous- Vikram Bisht, Manitoba Agricultureweeds also, but it is more important for the potato crop, Bisht explains in a phone interview. It can also be spread from field to field on machinery. Crop rotations are important to combat the disease. Brunswick. Despite the differences in genetics, there were What do you plant? Other crops than the potatoes, becausesimilar levels of internal necrosis produced in the tubers of potatoes are going to have a lot of disease, you can do that onlyInnovator and its parent Shepody from all AMV isolates. These for so long, he adds. The other alternatives is grow somethingresults show the amount of internal necrosis in AMV-infected which will resist expression of the disease. It will reduce thetubers depends on potato cultivar rather than AMV strain.losses, even if the virus is present in the tubers. PMTV on the other hand is a soilborne disease making soil Potatoes with skin defects caused by powdery scab anddetection of it imperative. In the past this has been done through common scab are graded out at higher levels from the freshbait plants along with enzyme linked immunosorbent assay industry. In the processing industry these scab diseases increase(ELISA), or with reverse transcription (RT)-polymerase chain the time needed to peel the potatoes for use. reaction (PCR).PMTV can also cause problems in storage. Brown striations inIn Nies first study, PMTV was detected using the bait plant test. the tubers will appear after being in cold storage and get worseTobacco plants used as bait were grown in soil from potato fields the longer the potatoes are in storage. Bisht explains infectedwhere PMTV or Spongospora subterranea f. sp. Subterranea tubers are found during processing making them unable to be(Sss)-infected tubers had been found. The bait plants were then used in some incidences. tested for PMTV using RT-PCR analysis.Nie and his team were able to develop a procedure called high Identifying Necrotic Viruses resolution DNA melting (HRM) assay for detection of both PMTV As part of Nies research on AMV, he was able to find four AMVand its protist vector, Sss, from soil directly. When the test was used susceptible potato cultivars to test. AMV was inoculated intoon soil samples from fields across New Brunswick where PMTV or the cultivars, Innovator, Yukon Gold, Rochdale Gold-Doree andSss infected tubers had been found, PMTV or Sss was found in 63 Shepody, which then developed tiny necrotic spots and calicoto 100 per cent of samples. Samples from fields with no infected symptoms on new leaves. The other cultivars tested only showedtubers, were found to have no PMTV or Sss discovered.calico symptoms on new leaves. Previous tests had required the bait plant to be tested for Huimin Xu with the Canadian Food Inspection Agency inPMTV infection, with Nies teams findings the soil in a suspected Prince Edward Island collected several AMV isolates/strainsinfected field can be tested now instead, making for a faster which were then studied along with the isolate from Newdiagnosis. SPUDSMART.COM Summer 202235'