POLLEN TRANSMISSION OF PEACH LATENT MOSAIC VIROID
M. Barba, E. Ragozzino, F. Faggioli
Peach latent mosaic viroid (PLMVd), the causal agent of peach latent mosaic disease, is transmissible by grafting and pruning tools and, occasionally, by aphids. There is no information on other possible ways of transmission. The high incidence of field infections and the rate of natural spread (5-10% of newly infected plants per year), prompted us to investigate the role, if any, that pollen, seed and root contact could play in PLMVd dissemination. The viroid was detected by molecular assays in pollen, seeds and roots of infected trees. Five out of 18 plants, pollinated with pollen from infected trees, became positive for PLMVd. Seeds from PLMVd-infected trees were also viroid-positive, but their seedlings were apparently viroid-free. PLMVd was not detected in the roots of healthy seedlings grown for six years in a container together with infected seedlings, indicating that no transmission had occurred via roots. Thus PLMVd is pollen-transmitted but is not transmitted through seeds nor roots of infected peach plants.