Molecular and serological characterization of a distinct
potyvirus causing latent infection in calla lilies
, Hei-Ti HSU
, Ying-Huey CHENG
, Chun-Huei HUANG
, Jye-Yann LIAO,
, and Chin-An CHANG
Plant Pathology Division, Taiwan Agricultural Research Institute, Wu-Feng, Taichung 413, TAIWAN
U.S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD
(Received September 19, 2005; Accepted March 10, 2006)
ABSTRACT. A virus (isolate: Ca-M19) capable of inducing local lesions on Chenopodium quinoa Willd.
was isolated from calla lilies (Zantedeschia spp.). Subculture of Ca-M19 was easily maintained in C. quinoa,
but a back inoculation from single lesion of C. quinoa to calla lilies has so far not been successful. Typical
potyvirus-like flexuous particles were consistently detected in Ca-M19 infected plants, and a 1.3-kb DNA
fragment was amplified
from these plants by reverse-transcription polymerase chain reaction (RT-PCR)
using potyvirus degenerate primers. The PCR product was cloned and its sequence analyzed (AF469171).
The amplicon was revealed to correspond to the 3¡¦ terminal region of a potyviral genome. After comparing
this sequence with known potyvirus sequences in the GenBank, we considered the virus a new species
of Potyvirus based on the uniqueness in its coat protein gene (CP) and the 3¡¦ non-coding region (NCR).
Comparative studies showed that Soybean mosaic virus (SMV) and Watermelon mosaic virus 2 (WMV 2)
were the two most similar potyviruses with Ca-M19, but they shared only 80% of nucleotide identities in CP
and NCR with Ca-M19. Attempts to purify a sufficient quantity of Ca-M19 from C. quinoa for preparation
of antibodies were unsuccessful. Alternatively
Ca-M19 CP was expressed by the vector pET28b and puri-
fied from E. coli culture, and polyclonal antibodies were prepared in rabbits. The antibody was applied in
ELISA, Western blotting, SDS-immunodiffusion and immuno-specific electron microscopy for the detection
of Ca-M19 in calla lilies. It did not react with at least five calla lily infecting potyviruses, including Dasheen
mosaic virus, Bean yellow mosaic virus, Konjak mosaic virus, Turnip mosaic virus, and Zantedeschia mild
mosaic virus. Indirect ELISA and SDS-immunodiffusion tests showed that Ca-M19 was serologically related,
but distinct from Bean common mosaic virus (BCMV), Black cowpea mosaic virus (BlCMV), Melon vein
banding mosaic virus (MVbMV), Passionfruit mottle virus (PaMV), Passionfruit crinkle virus (PCV), Pas-
sionfruit woodness virus (PWV), Soybean mosaic virus (SMV), Watermelon mosaic virus 2 (WMV 2), and
Zucchini yellow mosaic virus (ZYMV). Besides serological techniques, a primer pair (M19u/M19d) and a
DNA probe were designed which could also specifically detect and differentiate Ca-M19 from other viruses.
By the use of specific antibodies in ELISA, Ca-M19 was frequently detected in calla lily plants collected
from several major calla lily production townships in Taiwan. Among 86 field samples positively reacting
to the antibody, 77 of them exhibited evident systemic mosaic symptoms, but these symptomatic plants were
confirmed to be infected simultaneously by other viruses. Nine plants were found to be infected by Ca-M19
alone. These plants were confirmed to have remained symptomless throughout a 6-month observation period.
Therefore, we propose naming this isolate Calla lily latent virus (CLLV) for its inability to develop any
visible symptoms on calla lily.
Keywords: Calla lily; Coat protein expression; Potyviruses; Sequence analysis; Serology.
Botanical Studies (2006) 47: 369-378.
Corresponding author: E-mail: firstname.lastname@example.org.
tw; Fax: 886-4-23331089; Tel: 886-4-23302803.
mosaic virus (DsMV) is considered the most prevalent
and widespread in the family Araceae, including Zant-
edeschia spp. (Zettler et al., 1978; Zettler and Hartman,
1995). In addition to DsMV, several Potyvirus species¡X
including Bean yellow mosaic virus (BYMV) (Pham et al.,
2002), Konjak mosaic virus (KoMV) (Chang et al., 2001;
Hu, 2001; Kwon et al., 2002; Pham et al., 2002), Turnip
mosaic virus (TuMV) (Chen et al., 2003a)
schia mild mosaic virus (ZaMMV) (Chen et al., 2003b;
Calla lily (Zantedeschia spp.), an aroid plant species, is
a popular ornamental crop in Taiwan and many parts of the
world. Viral diseases and bacterial soft rot are the major
factors limiting its production. Among viruses, Dasheen