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2004 Plant Management Network.
Accepted for publication 14 July 2004. Published 9 August 2004.


Canna yellow mottle virus Detected in Canna in Florida


M. Timur Momol, University of Florida, IFAS, Department of Plant Pathology, North Florida Research and Education Center, Quincy 32351; Benham E. L. Lockhart, University of Minnesota, Department of Plant Pathology, St. Paul 55108; Hank Dankers, University of Florida, IFAS, North Florida Research and Education Center, Quincy, FL 32351; and Scott Adkins, USDA-ARS-USHRL, Fort Pierce 34945


Corresponding author: Timur (Tim) Momol. tmomol@ufl.edu


Momol, M. T., Lockhart, B. E. L., Dankers, H., Adkins, S. 2004. Canna yellow mottle virus detected in canna in Florida. Online. Plant Health Progress doi:10.1094/PHP-2004-0809-01-HN.


Cannas are herbaceous flowering plants native to the tropics and subtropics. They are widely cultivated as ornamentals in Florida although their precise economic value to the nursery industry is not documented. The occurrence of a yellow mottle disease of canna (Canna indica) characterized by veinal necrosis and mottling, and caused by a small non-enveloped bacilliform virus, Canna yellow mottle virus (CaYMV), was first reported in North America in 1988 in Minnesota (3). This virus represents a species of the genus Badnavirus in the Caulimoviridae.

Symptoms similar to this disease were observed in outdoor and greenhouse-grown canna plants in Florida in the spring of 2003 and winter of 2004, respectively. Symptoms included foliar chlorotic and necrotic mottle and veinal streaking (Fig. 1). The incidence of symptomatic canna was more than 60% (~18,000 symptomatic potted plants) in the same nursery in both years.



A
 
B

Fig. 1. Canna yellow mottle symptoms (chlorotic and necrotic mottle, veinal streaking) in leaves of canna infected with Canna yellow mottle virus. Symptoms on (A) Canna sp. with red leaves and (B) Canna sp. with green leaves.


Partially purified extracts from symptomatic leaves were examined by electron microscopy (EM) and by immunosorbent electron microscopy (ISEM) as described previously (1) using a broad-spectrum antiserum raised against a mixture of Sugarcane bacilliform virus and Banana streak virus isolates (5). Typical badnavirus-like particles were observed in extracts from symptomatic (Fig. 2) but not from asymptomatic canna plants.


 

Fig. 2. Transmission electron micrograph of isolated Canna yellow mottle virus virions.

 

The presence of CaYMV in symptomatic plants was confirmed by PCR amplification using CaYMV-specific primers CaYMV-3 and CaMYV-4. These primers were derived from the sequence of an ~1.4 kb PCR product previously amplified from CaYMV virion DNA using degenerate primers BADNA T and BADNA 2 (4, Lockhart unpublished data). The priming sites are located in two conserved regions of the badnavirus genome, the tRNAmet binding site in the intergenic region and the reverse transcriptase (RT) domain in ORF III, respectively. The sequence of the forward primer (CaYMV-3) was 5- GAC TTC CTG GGT GCA ACA AT -3 and the sequence of the reverse primer (CaMYV-4) was 5- TCT GTG CAA TCT TGG CGT AG -3. These CaYMV-specific primers amplified a PCR product (Fig. 3) of the predicted size (565 bp) from total DNA extracted from infected plants using a Plant DNeasy Mini Kit (Qiagen, Inc., Valencia, CA). No PCR product was obtained from equivalent DNA extracts from asymptomatic plants.


 

Fig. 3. Detection of Canna yellow mottle virus (CaYMV) infection in canna plants by PCR. Total DNA was extracted from leaves of symptomatic (Lanes 1 and 2) and non-symptomatic (Lanes 3 and 4) canna plants, amplified by PCR with CaYMV-specific primers, analyzed by agarose gel electrophoresis and stained with ethidium bromide. Lane M contains markers with sizes in kb indicated to the left of the gel.

 

To determine if the PCR products were amplified from the CaYMV genome, they were purified using a QIAquick PCR purification kit (Qiagen, Inc.) and cloned using a Qiagen PCR CloningPlus kit (Qiagen, Inc.). Clones were screened by PCR for the presence of an ~565 bp insert. Five PCR-positive clones were sequenced bidirectionally and the edited sequences were compared to that of the original CaYMV genomic sequence. The nucleotide sequences of the five clones obtained from symptomatic cannas were > 99.5% identical to each other and to the original CaYMV genomic sequence. These results confirm the identity of CaYMV in these canna samples.

Based on symptoms, EM, ISEM, PCR, and sequence analysis it is concluded that CaYMV, previously reported in Japan (6) and in Minnesota, USA (3), is also present in Florida. There is no known vector for this virus (3). This disease is distinct from canna mosaic, which is caused by an aphid-transmitted virus (2). Current recommendations for management of this virus in cannas are to destroy plants with typical symptoms and to use only virus-free rhizomes (which can be indexed by PCR) for propagation. Canna yellow mottle can be an economically important disease constraint on the production of cannas in Florida.


Literature Cited

1. Ahlawat, Y. S., Pant, R. P., Lockhart, B. E. L., Srivastava, M., Chakraborty, N. K., and Varma, A. 1998. Association of a badnavirus with citrus mosaic disease in India. Plant Dis. 80:590-592.

2. Brierley, P. and Smith, F. F. 1948. Canna mosaic in the United States. Phytopathology 38:230-234.

3. Lockhart, B. E. L. 1988. Occurrence of Canna yellow mottle virus in North America. Acta Hort. 234:69-72.

4. Lockhart, B. E. L., and Olszewski, N. E. 1993. Serological and genomic heterogeneity of banana streak badnavirus: Implications for virus detection in Musa germplasm. Pages 105-113 in: Breeding Banana and Plantain for Resistance to Disease and Pests. J. Ganry, ed. CIRAD/IRFA/INIBAP, Montpellier, France.

5. Ndowora, T. C., and Lockhart, B. E. L. 2000. Development of a serological assay for detecting serologically diverse banana streak virus isolates. Acta Hort. 540:377-388.

6. Yamashita, S., Natsuaki, T., Doi, Y.,and Yora, K. 1985. Canna yellow mottle virus, a non-enveloped small-bacilliform virus in Canna sp. Ann. Phytopathol. Soc. Japan 51:642-646.