Causal agent(s) and transmission
Pepino mosaic virus (PepMV) belongs to the same family (Potexvirus) as PVX and is therefore also transmissible by plant-to-plant contact. In the past, the only known natural host was Solanum muricatum (pepino).
The infected plants showed a distinct yellow mosaic pattern and the virus was reported only in the coastal region of Peru.
However, since 2000, PepMV has been found in Europe on glasshouse tomatoes, first in the Netherlands and the UK, and then in other European countries. It has been responsible for some spectacular damage to tomatoes cultivated under glasshouses, suggesting that it should be added to the EPPO Alert List. Experimental studies conducted by the French Potato Quarantine Station showed that the virus is capable of multiplying in the potato.
The percentage of transmission of the virus to the daughter tubers ranged from 25 to 100% depending on the cultivar.
Naturally found on pepino (Solanum muricatum) and tomato (Lycopersicon esculentum), the virus may infect experimentally most Solanaceous plants, including potato and tobacco.
Symptoms on foliage
The tests conducted under glasshouse conditions, using manual inoculation by a tomato isolate, showed varying reactions according to the cultivar:
- systemic infection with symptoms of aucuba mosaic and crinckling (Roseval: photo 1, Charlotte: photo 2);
- necrosis on the inoculated leaves then on the upper leaves, indicating a form of resistance of these cultivars to the virus (Spunta and Monalisa);
- no sign of infection (on cultivars such as Désirée, Nicola and Bintje).
Pepino mosaic potexvirus is transmitted by contact: contaminated tools, hands, clothing, direct plant-to-plant contact, and propagation (grafting, cuttings). Seed transmission is unlikely, as it is generally not observed in potexviruses. The same applies to insect transmission.
Affected tomato plants show yellow spots on the leaves, mild interveinal chlorosis and in some cases leaf malformations.
Tomato fruits sometimes show discolouration and infected plants may be stunted and distorted. The disease may spread very rapidly.