Further molecular evidence of the non-transmission of Plum pox potyvirus through seeds
Plum pox potyvirus (PPV - EPPO A2 quarantine pest) is naturally transmitted in orchards by several aphid species, and is also spread by the use of infected propagating material. The possibility of seed transmission has been subject to controversy. In the past, there have been some records of seed transmission in apricot from Hungary, and in plum and peach from Romania. However, other researchers could never confirm these results. Further studies using serological tests revealed the presence of the virus in coat and cotyledons (including embryonic tissues) in seeds collected from infected apricot, plum and peach trees, but never in seedlings obtained from infected seeds.
The question of seed transmission of PPV was addressed again using serological and molecular techniques. 12 different apricot and 6 peach cultivars naturally infected by PPV strains D and M, were used in this study. All plants tested positive in IC-RT-PCR and the strains (PPV-D and PPV-M) were characterized by several molecular and serological assays. The presence of PPV was studied in ripe seeds collected from these naturally infected plants, in germinating seeds and in seedlings. Seedlings were maintained in aphid-proof conditions for over 3 years (apricot) or over 6 months (peach) and regularly tested. ELISA and IC-RT-PCR showed that ripe seeds presented high percentage of virus infection (for both PPV-D and PPV-M), and that the virus was mainly present in seed coat, although cotyledons were also infected. Analysis during germination, showed that the virus remained confined to reserve tissues and did not replicate in the meristem. Apricot and peach seedlings never showed symptoms and, when tested by molecular assays, always gave negative results. The authors concluded that PPV-D and PPV-M are not transmitted by apricot and peach seeds.
Pasquini, G.; Simeone, A.M.; Conte, L.; Barba, M. (2000) RT-PCR evidence of the non-transmission through seed of Plum pox virus strains D and M.
Journal of Plant Pathology, 82(3), 221-226.