A new mosaic disease of Amazon lily in Taiwan

Mosaic symptoms were observed in leaves of Amazon lily (Eucharis grandiflora) grown commercially in Taiwan (Fig. 1). Leaf extracts caused necrotic local lesions when mechanically inoculated onto leaves of Chenopodium amaranticolor, Chenopodium quinoa and Gomphrena globosa, whereas seedlings of Nicotiana benthamiana showed a systemic mild mosaic (Fig. 2). Transmission electron microscopy showed flexuous rods, approximately 700-780 nm long, in leaf extracts. In indirect ELISA, symptomatic plants tested positive using a monoclonal antibody specific to the potyvirus group (Agdia Inc., Elkhart, IN, USA). Two potyviruses have been reported to infect Amazon lily: Amazon lily mosaic virus (ALiMV) (Terami et al., 1993) and Hippeastrum mosaic virus (HiMV) (Jayasinghe & Dijkstra, 1979). Based on symptomatology, the virus isolate resembled ALiMV, as this causes a systemic mosaic in N. benthamiana, whereas HiMV does not infect this host (Brunt et al., 1996). Therefore, we tentatively identified the virus as ALiMV, although the presence of previously uncharacterised potyviruses cannot be excluded.

The 3'-terminal region of ALiMV was amplified by RT-PCR from a total RNA extract from diseased plants using a potyvirus-specific degenerate forward primer (5'-GGBAAYAATAGTGGNCAACC-3') and an oligo-dT reverse primer. A 1.6-kb amplicon was cloned into pGEM-T^® Easy Vector (Promega, WI, USA), sequenced, and then analyzed using the GCG program of Wisconsin Package Version 10.3 (Accelrys Inc., San Diego, CA, USA). When compared to twenty-two potyviruses, the deduced amino acid sequence of the coat protein, showed 40% identity to Dasheen mosaic virus (DsMV) and 55% identity to Ornithogalum mosaic virus (OrMV).