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First Report of Turnip yellows virus in Daphne odora in New Zealand

Veerakone, S., Tang, J., Zheng, A., Ward, L. I.
Plant disease 2018 v.102 no.7 pp. 1467
Amaranthaceae, Aphidoidea, Beet western yellows virus, Brassicaceae, DNA-directed RNA polymerase, Daphne mosaic virus, Daphne odora, Fabaceae, Turnip yellows virus, analytical kits, crops, genes, genetic databases, host range, mixed infection, plant diseases and disorders, plant viruses, reverse transcriptase polymerase chain reaction, spring, viruses, winter, New Zealand
Daphnes are grown for their beautiful and intensely fragrant blooms, which are usually produced in winter or spring. In October 2016, a sample of Daphne odora (winter Daphne) from a home garden, showing stunted growth and chlorosis on leaves, was received at the Ministry for Primary Industries Plant Health and Environment Laboratory, Auckland, New Zealand (NZ). Total nucleic acid (NA) was extracted from the infected daphne leaves using a KingFisher mL Purification System (Thermofisher Scientific, Waltham, MA) with an InviMag Plant DNA Mini Kit (Stratec, Berkenfeld, Germany), following the manufacturer’s instructions. DNA was removed from the NA by treatment with DNase 1 using the Ambion DNA-free Kit (Life Technologies). Both cDNA and library were prepared using the NEBNext Ultra RNA Library prep Kit for Illumina (New England BioLabs) according to the manufacturer’s instructions and sequenced using an Illumina MiSeq sequencing platform with MiSeq Reagent Kit v2 (500 cycles). De novo sequence assembly and analysis was performed using Geneious 10.0.6 (Biomatters Ltd, Auckland, NZ) and the first thousand contigs were analyzed against the nucleotide database in GenBank by BLASTn. Five contigs of viral origin were found. Nucleotide blast searches of two of the contigs (2.5 and 2.2 kb) showed 94 and 96% identity to Turnip yellows virus (TuYV) (nt 11 to nt 2546 and nt 2147 to nt 4371 of GenBank accession no. JQ862472). Another two contigs had 83 and 86% identity to Daphne virus Y (DVY) (KU556609) and one contig had 77% identity to Butterbur mosaic virus (ButMV) (100, 90, and 78% coverage, respectively). To confirm the detection of TuYV obtained from Illumina sequencing, total NA from the daphne sample was tested by RT-PCR using primers TuYVorf0F and TuYVorf0R (Wilson et al. 2012). An amplicon of the expected size (780 bp) was obtained, directly sequenced, and deposited in GenBank (MG267049). BLASTn analysis showed 91% nt identity with the RNA polymerase gene of TuYV (X13063). TuYV infection was also confirmed serologically using a commercial double-antibody sandwich (DAS)-ELISA diagnostic kit (DSMZ AS-0049) to detect Beet western yellows virus and the closely related species TuYV. TuYV (genus Polerovirus) is an aphid transmitted virus and has a wide host range, which includes many commercially important crops belonging to Brassicaceae, Fabaceae, and Chenopodiaceae (Stevens et al. 2008). This virus causes severe damage to a number of arable crops; however, its role as the causal agent for the symptoms observed in daphne is unknown as plants were co-infected with DVY and BuMV. To our knowledge, this is the first report of natural occurrence of TuYV in the family Thymelaeaceae in the world.