Occurrence of Cucumber green mottle mosaic virus on Cucurbitaceous Plants in China.

Cucumber green mottle mosaic virus (CGMMV) was first discovered in 2003 in China (2) and developed an epidemic during 2005 (1). To know the occurrence scale and damage level of CGMMV, a survey was carried out in the main areas of cucurbitaceous plant production and seed trading in 2006 and 2007 in Mainland China. Samples of 739 plants of 16 types (seed samples from Cucurbita moschata, Cucumis melo, Lagenaria siceraria, Cucumis sativus, Momordica charantia, L. siceraria var. clavata, and C. pepo, leaf samples from C. moschata, Cucumis melo, L. siceraria, Cucumis sativus, and M. charantia, fruit samples from C. moschata, Citrullus lanatus, and L. siceraria, and seedling samples from Citrullus lanatus) were collected from 13 regions and analyzed by a double antibody sandwich (DAS)-ELISA. CGMMV was detected in Citrullus lanatus, L. siceraria, Cucumis melo, and C. moschata from six regions in 2006. Citrullus vulgaris, Cucumis melo, and C. moschata were infected most frequently; in 76, 60, and 30 of the leaf samples, respectively. CGMMV was tested positive in the samples of 8 seedlings, 23 seeds, and 1 fruit. In contrast, all samples tested negative in 2007. To confirm CGMMV identification, ELISA-positive samples were detected by reverse transcription-PCR assay using virus-specific primers that amplified a 524-bp fragment in the coat protein coding region. The nucleotide sequence of the PCR product (GenBank Accession No. DQ997778) isolated form L. siceraria in Liaoning Province (LHP) showed 100% identity with the Japanese watermelon strain (Japan W) and 91% identity with the Greece GR5 strain. On the basis of the symptoms of indicator plants (chlorotic spot and systemic mosaic were observed in L. siceraria, Chenopodium amaranticolor, and Cucumis sativus; no infection was observed in Datura stramonium, Nicotiana tabacum, and Chenopodium quinoa) and coat protein nucleotide sequence comparisons, the two CGMMV isolates of Wcn (1) and LHP from China should be grouped into the watermelon strain. The results showed that the government should establish effective quarantine strategy and the growers take proper planting measures to avoid further spreading of this virus. References: (1) H. Y. Chen et al. Acta Phytopathol. Sin. 36:306, 2006. (2) B. X. Qin et al. Plant Quarantine. 19:4, 2005.