First Report of Dasheen mosaic virus Infecting Lotus (Nelumbo nucifera) in China.

Nelumbo nucifera (lotus) is a perennial aquatic plant belonging to the family Nelumbonaceae. In China, lotus is cultivated as vegetable, ornamental plant, or herbal medicine with a total land area of approximately 1 × 106 ha. Viral disease in lotus is reportedly caused by Cucumber mosaic virus (CMV), which results in stunted growth and malformation in infected plants (Ding et al. 2011). Dasheen mosaic virus (DsMV), which belongs to the genus Potyvirus in the familyPotyviridae, mainly attacks various cultivated aroids and can be transmitted by aphid species (Elliott et al. 1997; Zettler et al. 1987). In February 2014, an unknown pale-green mosaic symptom was observed in the leaves of lotus grown at the Lotus Germplasm Repository of Wuhan University. Severely infected lotus leaves eventually curled and shrank, and the growth of rhizomes was also affected by this unknown disease. In the field, the incidence of this disease in lotus was as high as 8%. To identify the pathogen of this disease, 30 infected lotus samples were collected for analysis with double-antibody sandwich (DAS)-ELISA kit and reverse transcription (RT)-PCR. First, infected lotus leaves showing pale green mosaic symptom were analyzed using DsMV-ELISA kit (Dongge Co. LTD) in accordance with the manufacturer’s protocol, and the healthy lotus leaves were used as negative control. Absorbance at 450 nm was read in ELISA reader within 15 min after adding stop solution. Results showed that the infected lotus samples were positive to DsMV. These DsMV-positive samples were further analyzed by RT-PCR using a pair of specific primers (forward, 5′-GGGCTTGGGTGATGATGGA-3′; reverse, 5′-GCCTTTCAGTGTTCTCGCTTG-3′) designed on the basis of core nucleotide sequences of the DsMV cp gene. As expected, the amplified PCR product was 357 bp in size, and this product was sequenced and then this sequence was deposited in GenBank (Accession No. KP692755). BLAST results showed high sequence similarity ranging from 84 to 95% between the tested sample and other published DsMV isolates. The virus isolated from DsMV-positive samples was mechanically transmitted to the healthy lotus. After 10 days, a pale green mosaic symptom appeared in the leaves. ELISA and RT-PCR results showed that DsMV was positive and CMV was negative in these artificially infected lotus samples. Both serologic and molecular test results confirmed that DsMV is the pathogen that caused the disease in lotus. This case provides the first report of DsMV infection in lotus in China. To our knowledge, CMV was the only pathogen reported to cause viral disease in lotus. In this study, we identified DsMV as a new pathogen causing viral disease in lotus. Our results will be highly valuable for disease prevention and control in lotus cultivation. © 2015 American Phytopathological Society. All rights reserved.