New Natural Hosts of Pepino mosaic virus in Spain.

Pepino mosaic virus (PepMV) was first detected in Spain in 2000 (1). The virus infects tomato (Lycopersicon esculentum Mill.) crops and causes a variety of symptoms including leaf distortion, chlorosis, mosaic, blistering of the leaf surface, green striations on the stem and sepals, and fruit discoloration. PepMV is present along the southern and eastern regions of Spain (provinces of Granada, Almeria, Murcia, Alicante, Valencia, and Barcelona), Balearic, and the Canary Islands. In the summer and autumn of 2001 and 2002, virus-like symptoms were observed in native plants growing in or around tomato fields in Murcia and Almeria provinces. To study the alternate hosts that may serve as virus reservoirs, 62 samples of 42 common weed species, including asymptomatic plants, were collected and analyzed for PepMV using double-antibody sandwich enzyme-linked immunosorbent assay with a commercial antiserum (DSMZ As-0554; Biologische Bundesantstal, Braunschweig, Germany). The following weed hosts tested positive for PepMV: Bassia scoparia (L.) Voss., Calystegia sepium (L.) R.Br., Chenopodium murale L., Convolvulus althaeoides L., Convolvulus arvensis L., Conyza albida Willd. ex Spreng., Coronopus sp., Diplotaxis erucoides (L.) DC, Echium creticum L., E. humile Desf., Heliotropium europaeum L., Moricandia arvensis (L.) DC., Onopordum sp., Piptatherum multiflorum (Cav.) Beauv., Plantago afra L., Rumex sp., Sisymbrium irio L., Sonchus tenerrimus L., and Taraxacum vulgare (Lam.) Schrank. The presence of PepMV in these weed species was confirmed using reverse transcription-polymerase chain reaction with primers specific for PepMV (2). Although the number of samples examined may be insufficient to assess precisely the role of weed reservoirs in outbreaks of PepMV, these findings reveal potential virus sources and contribute to further understanding of PepMV epidemiology in Spain. References: (1) C. Jordá et al. Plant Dis. 85:1292, 2001. (2) P. Martínez-Culebras et al. Eur. J. Plant Pathol. 108:887, 2002.