Effects of Beet necrotic yellow vein virus in Spinach Cultivars

Pest categorisation of beet necrotic yellow vein virus

Following a request from the EU Commission, the Panel on Plant Health performed a categorisation of beet necrotic yellow vein virus (BNYVV), the causal agent of the sugar beet rhizomania disease. The virus is currently listed in Annex III as a protected zone (PZ) quarantine pest of the Commission Implementing Regulation (EU) 2019/2072. The identity of the BNYVV is well established. BNYVV is a soil-borne virus transmitted by the obligate root plasmodiophorid endoparasite Polymyxa betae. BNYVV is widely distributed in the EU, but is not reported in the following EU PZs: Ireland, France (Brittany), Portugal (Azores), Finland and Northern Ireland. The virus may enter, become established and spread in the PZs via P. betae resting spores with soil and growing media as such or attached to machinery and with roots and tubercles of species other than B. vulgaris and with plants for planting. Introduction of BNYVV would have a negative impact on sugar beet and other beet crops in PZs, because of yield and sugar content reduction. Phytosanitary measures are available to reduce the likelihood of entry and spread in the PZs. Once the virus and its plasmodiophorid vector have entered a PZ, their eradication would be difficult due to the persistence of viruliferous resting spores in the soil. The main knowledge gaps or uncertainties identified concerning the presence of BNYVV in the PZs and the incidence and distribution of BNYVV in Switzerland, a country to which a range of specific requirements do not apply. BNYVV meets all the criteria that are within the remit of EFSA to qualify as a potential protected zone union quarantine pest. Plants for planting are not considered as a main means of spread, and therefore BNYVV does not satisfy all the criteria evaluated by EFSA to qualify as potential Union regulated non-quarantine pest.

Highly Specific Detection of Five Exotic Quarantine Plant Viruses using RT-PCR

To detect five plant viruses (Beet black scorch virus, Beet necrotic yellow vein virus, Eggplant mottled dwarf virus, Pelargonium zonate spot virus, and Rice yellow mottle virus) for quarantine purposes, we designed 15 RT-PCR primer sets. Primer design was based on the nucleotide sequence of the coat protein gene, which is highly conserved within species. All but one primer set successfully amplified the targets, and gradient PCRs indicated that the optimal temperature for the 14 useful primer sets was 51.9°C. Some primer sets worked well regardless of annealing temperature while others required a very specific annealing temperature. A primer specificity test using plant total RNAs and cDNAs of other plant virus-infected samples demonstrated that the designed primer sets were highly specific and generated reproducible results. The newly developed RT-PCR primer sets would be useful for quarantine inspections aimed at preventing the entry of exotic plant viruses into Korea.