Iris yellow spot virus - dangerous pathogen of onion vegetable crops

Vegetable crops are the mainstay of nutrition in the world. Different types of onions are grown around the world and are a source of vitamins and nutrients. The area under onion crops in the world has increased from 5.3 million ha in 2016 to 5.7 million ha in 2020. Harvested yields also increased from 99.5 million tons in 2016 to 109 million tons in 2020.Iris yellow spot virus, IYSV, a member of the genus Orthotospovirus, affects various onion species (mainly Allium cepa and Allium porrum), garlic and several flowering plants. It was first identified in Brazil in 1981. Infected onion plants show numerous symptoms like ring spots on leaves and stems. It should be noted that the economic impact of IYSV varies, with small losses in the Netherlands, whereas in Brazil losses of up to 100% in onion fields have been observed. IYSV is effectively transmitted by Thrips tabaci. A number of weeds are reservoirs of IYSV. IYSV is now widespread in many countries around the world. It is regulated by the quarantine lists of Tunisia and Argentina and was previously regulated by EPPO. Highly sensitive and specific laboratory diagnostic methods are necessary to control the movement of planting material infected with IYSV. All-Russian Plant Quarantine Center, as a scientific institution of an EPPO member country, develops diagnostic methods for pests, including viruses, to prevent the introduction and spread of new pests.During this work, primers to different regions of the virus genome were designed and the results were compared with previously developed primers IYSV_1S/IYSV_1A to the virus N gene (Coutts et al., 2003) and IYSV459/TOS-R15 (Uga and Tsuda 2005) to the coat protein gene.PCR with primers IYSV_4F/IYSV_4R, IYSV_5F/IYSV_5R, and IYSV_6F/IYSV_6R showed the best results. It should be noted that the IYSV_1S/IYSV_1A primers were less specific, and the IYSV459/TOS-R15 primers had identical results, but with fewer amplicons. PCR products with primers IYSV_4F/IYSV_4R, IYSV_5F/IYSV_5R, and IYSV_6F/IYSV_6R were sequenced and the presence of IYSV was confirmed in NCBI Genebank analysis. Thus, it was shown that our designed primers can be recommended for the laboratory diagnosis.