December 29, 2004
Source: British Soc. Plant Pathol., New Disease Reports, Vol. 10 [edited]

First identification of Tobacco mild green mosaic virus on Capsicum annuum in Taiwan
C.-Y. Li and Y.-C. Chang, Department of Plant Pathology and Microbiology, National Taiwan University, Taipei,
Taiwan 10617, Republic of China. Accepted for publication 03/12/04

Peppers (_Capsicum annuum_) are important vegetables, and some cultivars are planted as ornamental plants because of their colorful fruits. In 2003, mild chlorosis and necrotic lesions were observed on pepper plants in the northern part of Taiwan.

When pepper leaf extracts from plants showing symptoms were mechanically inoculated onto leaves of _Chenopodium amaranticolor_ and _C. quinoa_, chlorotic lesions developed on the inoculated leaves. After 3 successive single lesion isolations on _C. amaranticolor_, an isolate of a virus was obtained. This isolate
caused only local lesions on inoculated leaves in many _Nicotiana_ spp. but produced systemic mosaic on _N. benthamiana_ and _N. debneyi_. In addition, inoculated pepper plants exhibited mild chlorosis symptoms and later became necrotic, followed by leaf drop.

Transmission electron microscopy revealed numerous rigid rods, approximately 300 nm in length, suggestive of tobamoviruses. There are at least 6 known tobamoviruses that are able to infect peppers: Paprika mild mottle virus (PaMMV), Pepper mild mottle virus (PMMoV), Ribgrass mosaic virus (RMV), Tobacco mild green mosaic virus (TMGMV), Tobacco mosaic virus (TMV) and Tomato mosaic virus (ToMV) (Brunt et al., 1996).

To identify the unknown virus, a poly(A) tail was added to the 3' end of the purified viral RNA using poly(A) polymerase, and cDNA fragments were subsequently amplified using a SMARTT RACE cDNA Amplification Kit (BD Biosciences, Palo Alto, CA, USA), before being cloned into a pGEM-T Easy Vector (Promega, Madison, USA).

2 independent clones were sequenced, and a BLAST search was performed against the NCBI database. The results clearly indicated that the clones contained a partial sequence of TMGMV with a 98 percent nucleotide identity to a Japanese isolate of TMGMV (accession number AB078435).

To our knowledge, this the 1st report of TMGMV identified in Taiwan.

References:

Brunt AA, Crabtree K, Dallwitz MJ, Gibbs AJ, Watson L, Zurcher EJ, 1996. Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 20th August 1996. <http://biology.anu.edu.au/Groups/MES/vide/>

Links:
<http://www.bspp.org.uk/ndr/jan2005/2004-80.asp>
<http://www.actahort.org/books/568/568_13.htm>

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[TMGMV probably occurs in all tropical and subtropical regions where _Nicotiana glauca_ is distributed (North America, Australia and many European and African countries, including Madeira, the Mediterranean and Canary Islands. Tobacco mosaic and odontoglossum ringspot viruses are closely related, and cucumber green mottle mosaic and sunn-hemp mosaic tobamoviruses are distantly related. Disease management involves application of phytosanitary measures, especially avoiding contact between infected and virus-free plants. Production benches
and equipment used in glasshouse production systems must be sterilized. - Mod.DH]