Detection and molecular characterisation of the Orthotospovirus iridimaculaflavi N gene of the onion in Poland

Abstract

Orthotospovirus iridimaculaflavi (iris yellow spot orthotospovirus, IYSV) is one of the most important viral pathogens affecting onions worldwide. The virus is predominantly transmitted by onion thrips and can cause significant losses in cultivated fields. In this study, the identification and molecular characterisation of IYSV isolates originating from onion crops in Poland were carried out. Symptomatic onion plants (Allium cepa L.) were observed in Kujawsko-Pomorskie, Lubelskie, and Wielkopolskie regions of Poland. The plants were characterised by various disease symptoms from mild to severe, resulting in deformation and growth reduction. A total of 40 onion samples were collected, and the presence of IYSV was confirmed in three of them. Moreover, the occurrence of Potyvirus cepae (onion yellow dwarf virus, OYDV) in single and mixed infections with IYSV was observed. The sequences of IYSV obtained in this study were compared with the sequences retrieved from the GenBank database, and the phylogenetic analysis was subsequently conducted. The maximum-likelihood reconstruction revealed that the Polish isolates mainly grouped with isolates originating from Serbia. To our knowledge, it is the first report of IYSV infecting onions in Poland