Main content area

First Report of Mulberry Vein Banding Virus Infecting Pharbitis purpurea in Yunnan, China

Gao, X., Jia, Z. Q., Yang, B. J., Tan, X. L., Liu, Y. T.
Plant disease 2019 v.103 no.8 pp. 2145
Capsicum chlorosis orthotospovirus, Groundnut bud necrosis tospovirus, Groundnut ringspot tospovirus, Hippeastrum chlorotic ringspot virus, Impatiens necrotic spot tospovirus, Ipomoea purpurea, Iris yellow spot tospovirus, Morus alba, Tomato chlorotic spot tospovirus, Tomato spotted wilt orthotospovirus, Tomato zonate spot virus, Watermelon silver mottle tospovirus, antibodies, antigens, enzyme-linked immunosorbent assay, medicinal plants, mulberries, necrosis, nucleocapsid proteins, oligodeoxyribonucleotides, phylogeny, plant diseases and disorders, plant viruses, surveys, viruses, China
Pharbitis purpurea (L.) Voigt is a wild medicinal plant (Convolvulaceae) that is native to tropical America but is widely distributed in southern and northern China. In June 2017, necrotic spots and concentric rings were detected on P. purpurea plants during a survey at Yunnan Agricultural University. Symptomatic plants were sampled for serological tests involving nine Tospovirus-specific antibodies and a reverse transcription PCR (RT-PCR) analysis. Five of the nine antibodies (targeting tomato spotted wilt virus [TSWV], impatiens necrotic spot virus [INSV], iris yellow spot virus, watermelon silver mottle virus [WSMoV]/groundnut bud necrosis virus [GBNV], and groundnut ringspot virus/tomato chlorotic spot virus) were purchased from Agdia (U.S.A.) and were used in a double-antibody sandwich ELISA. The other four antibodies (targeting Hippeastrum chlorotic ringspot virus [HCRV], tomato zonate spot virus [TZSV], calla lily chlorotic spot virus [CCSV], and Capsicum chlorosis virus [CaCV]) were generated in this study, with the viral nucleocapsid proteins serving as immunogens (Proteintech Group, China). These four antibodies were used in an indirect ELISA. The serological tests revealed that the virus infecting the P. purpurea plants (isolate YN-Pharbitis purpurea) could be detected by the antibodies for TZSV, CaCV, and WSMoV/GBNV. Three universal primer pairs, J13/UHP (Cortez et al. 2001), gM410/gM870c (Chen et al. 2012), and gL2470/gL3480c (Chen et al. 2012), as well as six primer pairs we designed to target HCRV, TSWV, TZSV, INSV, CCSV, and CaCV, were used for the RT-PCR tests. The gM410/gM870c primers (gM410, 5′-AACTGGAAAAATGATTTTGTTGG-3′; gM870c, 5′-ATTAGTTGCAGCTTCAATAAGC-3′) amplified a 460-bp product (Chen et al. 2012), which was sequenced. A BLASTn analysis indicated the amplified fragment was 88% identical to the MVBaV-XCSY-3 strain (KM819699.2) sequence submitted to the NCBI database in 2015. Thus, YN-Pharbitis purpurea is a mulberry vein banding virus (MuVBV) isolate. We designed seven primer pairs based on the mulberry vein banding associated virus (MVBaV) sequences reported by Meng et al. (2015) to amplify and clone the S, M, and L segments obtained by RT-PCR, which were sequenced and assembled. The segments were amplified with Prime STAR Max Premix (Takara). The assembled S, M, and L segments of YN-Pharbitis purpurea were 2,937 nt (MK239332), 4,729 nt (MK239333), and 8,906 nt (MK681486), respectively. A BLASTn analysis confirmed that the S, M, and L segments were 83, 84, and 86% identical to MVBaV-XCSY-3 sequences. The nucleocapsid protein of YN-Pharbitis purpurea was 90% identical to the corresponding MVBaV sequence. A phylogenetic analysis revealed that YN-Pharbitis purpurea clustered with MVBaV-XCSY-3. Additionally, MuVBV is a tentative species in the genus Tospovirus. Mulberry (Morus alba L.) was first identified as a host of MuVBV in Guangxi, China, in 2013 (Meng et al. 2013). To the best of our knowledge, this is the first report describing an infection of P. purpurea by MuVBV. Moreover, MuVBV was first reported in Yunnan, implying the virus is spreading in this region.