Incidence and distribution of leek yellow stripe virus in allium crops in Serbia

Abstract

Leek yellow stripe virus (LYSV) is one of the most frequent and important viruses in leek and garlic crops worldwide. In Serbia this virus is found both in leek and garlic, and often at high percentages. During two consecutive years, 2012 and 2013, a total 92 samples were collected from 11 inspected leek-, garlic- and onion-growing locations and they were analyzed for the presence of LYSV using DAS-ELISA. LYSV was detected in 31.5% of the tested samples. In 2012, the presence of LYSV was only detected in leek plants, and in 55.6% of the tested samples. During 2013, LYSV was detected in 85% of leek and 58.3% of garlic samples. In total, LYSV was detected in 56.4% of leek samples and 17.1% garlic samples. LYSV incidence was confirmed using RT-PCR with LYSV specific primers amplifying 1020 bp fragment representing coat protein and part of nuclear inclusion B genes. Molecular identification was confirmed by sequencing of two selected isolates, 181-13 (MG242625) from garlic and 298-13 (MG242624) from leek, and comparing them to the GenBank sequences of LYSV. Phylogenetic analysis of 55 sequences of LYSV from all over the world showed some correlation between host plant and geographical origin of the isolates, forming five separate clades. Two Serbian LYSV isolates fell into distant clades. The Serbian leek isolate 298-13 of LYSV belongs to clade B, while isolate 181-13 originating from garlic belongs in clade E.

Virus žute prugavosti praziluka (Leek yellow stripe virus, LYSV) je jedan od najčešćih i najznačajnijih virusa na praziluku i belom luku. U Srbiji je virus detektovan na obe kulture, i praziluku i belom luku, a često se javlja u visokim procentima. Tokom dve uzastopne godine (2013. i 2014.) pregledano je 11 lokaliteta gajenja praziluka, belog i crnog luka i sakupljena su 92 uzorka koja su DAS-ELISA metodom testirana na prisustvo LYSV. Prisustvo LYSV je dokazano u 31,5% testiranih uzoraka. Tokom 2012., prisustvo LYSV dokazano je samo u praziluku, u 55,6% testiranih uzoraka. Tokom 2013., LYSV je dokazan u 85% uzoraka praziluka i 58,3% uzoraka belog luka. Ukupno, prisustvo LYSV je dokazano u 56,4% uzoraka praziluka i 17,1% uzoraka belog luka. Prisustvo LYSV u testiranim uzorcima potvrđeno je primenom RT-PCR metode i specifičnih prajmera za LYSV koji umnožavaju fragment od 1020 bp koji obuhvata gen za proteinski omotač i deo gena za nuklearne inkluzije B. Molekularna identifikacija LYSV obavljena je sekvenciranjem dva odabrana izolata iz belog luka 181-13 (MG242625) i praziluka 298-13 (MG242624) i poređenjem dobijenih sekvenci sa sekvencama LYSV iz GenBank baze podataka. Filogenetske analize 55 sekvenci izolata LYSV iz različitih delova sveta ukazale su na delimičnu korelaciju između biljke domaćina i geografskog porekla izolata, formiranjem pet odvojenih grupa izolata u stablu. Dva izolata iz Srbije grupisala su se u udaljene grupe. Izolat iz Srbije iz praziluka 298-13 grupisao se u grupu B, dok se izolat iz belog luka 181-13 grupisao u grupu E.