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Submitted to: Acta Horticulturae
Publication Type: Proceedings Publication Acceptance Date: 5/5/2017 Publication Date: 2/2/2018 Citation: Hammond, J., Reinsel, M.D. 2018. Sequence variability between Plantago asiatica mosaic virus isolates. Acta Horticulturae. 1193:1-8. 10.17660/ActaHortic.2018.1193.1. DOI: https://doi.org/10.17660/ActaHortic.2018.1193.1 Interpretive Summary: Virus infections cause reductions in yield and quality of many crops. Vegetatively-propagated ornamental crops are prone to accumulation of viruses transmitted either mechanically or via vectored transmission in the course of crop production. Lilies are grown for their prominent flowers, and are known to be susceptible to a number of viruses. Over the past decade a damaging virus, Plantago Asiatic mosaic virus (PlAMV), was found first in Japan, then within Europe, and more recently in the USA and other countries, presumably by spread within the international bulb trade. Comparison of isolates of PlAMV identified from imported lilies in the USA to isolates reported from other countries and host plants identified three groups of isolates: a) from native and ornamental plants originating from northern Asia; b) from lilies in Japan; and c) from lilies grown in Europe and other countries. The ‘European’ lily isolates are distinct from those from lily in Japan, suggesting a different and as yet unknown origin. Knowledge of the occurrence and variability of the virus in imported lily bulbs will allow growers to seek stocks free of this damaging virus, and will aid regulatory officials in screening crops intended for import to the US. Technical Abstract: Plantago asiatica mosaic virus (PlAMV) was described four decades ago from the weedy species Plantago asiatica in the Russian Far East, but has also been reported from lilies (Lilium spp.) and primrose (Primula seiboldii) in Japan. More recently PlAMV has been reported in the Netherlands and elsewhere in Europe; in Taiwan; and in the United States in bulbs imported from the Netherlands. An isolate from heavenly bamboo (Nandina domestica) was initially described from California (USA) as Nandina mosaic virus at about the same time that PlAMV was described from Russia, and was recognized as a strain of PlAMV (PlAMV-NMV) only when the full sequence of a Nandina mosaic isolate (PlAMV-PLH) was determined; however, nandina is the only reported natural host of PlAMV-NMV. Lily isolates of PlAMV cause significant economic damage in lilies, especially Asiatic and Oriental hybrid types grown for cut-flower production. We have therefore determined the 3'-terminal sequence including the coat protein (CP) gene of multiple isolates from different imported lily cultivars, and compared these sequences to those of isolates from lilies and other hosts from different countries. To date the CP sequences of all isolates from imported lilies fall within the same ‘European’ clade as isolates from Europe, with minimal variation in amino acid sequence, whereas lily and primrose isolates from Japan form a separate ‘Japanese’ clade; PlAMV-Type and PlAMV-Gunwi (from P. asiatica) and PlAMV-PLH form a third, ‘Russian’ clade. Isolates of the ‘Russian’ clade share multiple N-terminal CP-residues that distinguish them from all other available PlAMV isolates; several variant N-terminal residues are uniquely conserved within the ‘European’ clade, and others within the ‘Japanese’ clade. These results support the serological differentiation of ‘European’ lily isolates from PlAMV-NMV, and suggest that ‘Japanese’ isolates may also be serologically distinct. |
