Assessment of the experimental host range of a lily isolate of Plantago asiatica mosaic virus (PlAMV), an emerging virus

Authors: Hammond, John; RANE, KAREN - University Of Maryland

Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 2/7/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: Emerging plant viruses can spread rapidly over wide geographic areas, and may infect species other than those initially identified as infected. A virus called Plantago asiatica mosaic virus, first identified in a weedy plant species common across northeastern Russia and east Asia, was independently reported to infect a woody ornamental host in the USA, and was only shown to be a variant of the same virus 30 years later. In 2010, another variant of the virus was detected in commercial lily stocks in Europe, and has subsequently spread to countries where ornamental lilies have been imported. To determine whether this virus could spread to other crops, two scientists in Maryland tested diverse ornamental plant species, commonly used virus bioassay plants, and various vegetable species as possible hosts for this virus. A total of 26 plant species representing 15 taxonomically diverse plant families were found to be susceptible to infection, with about half of these species infected systemically. In other experimental hosts, the virus was restricted to the inoculated leaves, indicating low potential for these species to act as virus reservoirs from which other plants might become infected. These results indicate that this virus is likely to adapt to a wide range of other host plants, over a broad geographic range.

Technical Abstract: Plantago asiatica mosaic virus (Plantago asiatica mosaic virus; PlAMV) is a member of the genus Potexvirus, family Alphaflexiviridae. PlAMV was originally reported from the weedy host Plantago asiatica in the Russian Far East, and from cultivated plants of Nandina domestica (heavenly bamboo) in California, USA, in the 1970’s. Although isolates from nandina were initially thought to belong to a distinct species named as ‘Nandina mosaic virus’ (NaMV), when the NaMV sequence was determined it was shown to be an isolate of PlAMV. PlAMV was later found naturally infecting edible lilies (Lilium leichtlinii var. maximowiczii) in Japan, and emerged in the Netherlands and Chile in ornamental lilies (Lilium hybrids) including Asiatic, Oriental, and Tiger lily types. PlAMV is readily transmitted between lilies via either roots or contaminated planting medium, and mechanical transmission during bulb processing or horticultural operations, and has since spread essentially worldwide through trade in ornamental lilies. To date at least ten species from nine diverse families are known to be naturally infected with PlAMV. The readiness of spread through contaminated planting medium or mechanical transmission suggest that other crop species might be at risk. The experimental host range of a lily isolate was determined by mechanical inoculation followed by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using antibodies raised against purified PlAMV. A total of 49 species representing 19 taxonomically diverse plant families were mechanically inoculated; of these, 24 species representing 13 plant families were infected either locally or systemically. In some species infection was latent, whereas in several others systemic necrosis was observed. Although PlAMV was initially thought to have a relatively narrow host range, it is now apparent that many more species, including multiple ornamentals, may be infected.